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NCERT Solutions for Class 10 Social Science Civics Chapter 5 Popular Struggles and Movements

These Solutions are part of NCERT Solutions for Class 10 Social Science. Here we have given Extra Questions for NCERT Solutions for Class 10 Social Science Civics Chapter 5 Popular Struggles and Movements.

TEXTBOOK EXERCISES

Question 1.
In what ways do pressure groups and movements exert influence on politics?
Answer:
Like an interest group, a movement group also attempts to influence politics rather than directly take part in electoral competition. But unlike the interest groups, movements have a loose organization. Their decision making is more informal and flexible. They depend much more on spontaneous mass participation than an interest group.

Question 2.
Describe the forms of relationship between pressure groups and political parties.
Answer:
In most cases, the relationship between parties and interest or movement groups is not so direct. They often take positions that are opposed to each other. Yet they are in dialogue and negotiation. Movement groups have raised new issues that have been taken up by political parties. Most of the new leadership of political parties comes from interest or movement groups.

Question 3.
Explain, how the activities of pressure groups are useful in the functioning of a democratic government.
Answer:
The activities of pressure groups are useful in the functioning of a democratic government in the following ways :

1. Deepens democracy and counter undue influence on the government : Sometime rich and powerful put pressure on the government to form a policy or take a decision in their interest. In such situations pressure groups can counter such move by putting pressure on the government to take a decision in the interest of ordinary citizens. To put pressure on the government in public interest is good and it strengthens democracy.
2. Sectional groups and balance of power : Even sectional interest groups play a valuable role. As there are different sectional groups, no one can achieve dominance over society. If one group brings pressure on government to make policies in its favour, another will bring counter pressure not to make policies in the way the first group desires. Thus, different sectional interest groups help the government to maintain a balance of power and accommodation of conflicting interests.

Question 4.
What is a pressure group ? Give a few examples.
Answer:
Pressure groups are organizations that attempt to influence government policies. But unlike political parties, pressure groups do not aim to directly control or share political power. These organizations are formed when people with common occupation, interests, aspirations, or opinions come together in order to achieve a common objective.

The struggle in Nepal was called a movement for democracy. We often hear the word people’s movement to describe many forms of collective action: Narmada Bachao Andolan, Movement for Right to Information, Anti-liquor Movement, Women’s Movement, Environmental Movement.

Question 5.
What is the difference between a pressure group and a political party ?
Answer:
A pressure group is an organised Or unorganised body that tries to promote its interests. They fight and try to achieve a common objective. They do not take part in competitive politics but try to influence the government by different means.
On the other hand, political parties take direct participation in competitive politics. They contest elections in order to win majority and form government. Their aim is to achieve political power. They have more than one interest. They have their own ideology and have their own way of achieving their aim.

Question 6.
Organisations that undertake activities to promote the interests of specific social sections such as workers, employees, teachers and lawyers are called …………….. groups.
Answer:
interest

Question 7.
Which among the following is the special feature that distinguishes a pressure group from a political
party ?
(a) Parties take political stances, while pressure groups do not bother about political issues.
(b) Pressure groups are confined to a few people, while parties involve larger number of people.
(c) Pressure groups do not seek to get into power, while political parties do.
(d) Pressure groups do not seek to mobilise people, while parties do.
Answer:
(c) Pressure groups do not seek to get into power, while political parties do.

Question 8.
Match List I (organisations and struggles) with List II and select the correct …………. answer using the codes given below the lists :

List I	List II
1. Organisations that seek to promote the interests of a particular section or group	A. Movement
2. Organisations that seek to promote common interest	B. Political parties
3. Struggles launched for the resolution of a social problem with or without an organisational structure	C. Sectional interest groups
4. Organisations that mobilise people with a view to win political power	D. Public interest groups

 

	1	2	3	4
(a)	C	D	B	A
(b)	c	D	A	B
(c)	D	C	B	A
(d)	B	C	D	A

Answer:
(b) C, D, A, B.

Question 9.
Match List I with List II and select the correct answer using the codes given below the lists :

List I	List II
1. Pressure group	A. Narmada Bachao Andolan
2. Long term movement	B. Asom Gana Parishad
3. Single issue movement	C. Women’s Movement
4. Political party	D. Fertiliser Dealers’Association

 

	1	2	3	4
(a)	D	C	A	B
(b)	B	A	D	C
(c)	C	D	B	A
(d)	B	D	C	A

Answer:
(a) D, C,A, B.

Question 10.
Consider the following statements about pressure groups and parties :
A. Pressure groups are an organized expression of the interests and views of specific social sections.
B. Pressure groups take positions on political issues.
c. All pressure groups are political parties.
Which of the statements given above are correct ?
(a) A, B and C
(b) A and B
(c) B and C
(d) A and C
Answer:
(b) A and B

Question 11.
Mewat is one of the most backward areas in Haryana. It used to be a part of district Gurgaon and Faridabad. The people of Mewat felt that the area will get better attention if it were to become a separate district. But political parties were indifferent to this sentiment. The demand for a separate district was raised by Mewat Educational and Social Organisation and Mewat Saksharta Samiti in 1996. Later Mewat Vikas Sabha was founded in 2000 and carried out a series of public awareness campaigns. This forced both the major parties, Congress and the Indian National Lok Dal, to announce their support for the new district before the assembly elections held in February 2005. The new district came into existence in July 2005. In this example, what is the relationship that you observe among movement, political parties, and the government? Can you think of an example that shows a relationship different from this one?
Answer:
It was a movement that was supported by different organizations viz., Mewat Educational and Social Organisation, Mewat Saksharta Samiti, and Mewat Vikas Sabha. The awareness campaigns started by Mewat Vikas Sabha forced two major parties, Congress and the Indian National Lok Dal to support them.

Generally, movements are started against the policies of the government. In the present case, the government of the Indian National Lok Dal was in power and it also supported the demand for the new district in view of coming elections in the state. None of the party wanted to go against the demands of the people. As Congress won the election in 2005 and had supported the movement, the new district came into existence in July 2005.

Thus, this movement was different from other movements. In other movements such as Narmada Bachao Andolan, different organizations were against the policy of the government regarding the construction of big dams. In such a movement, the government is not a party to the movement.

We hope the NCERT Solutions for Class 10 Social Science Civics Chapter 5 Popular Struggles and Movements help you. If you have any query regarding NCERT Solutions for Class 10 Social Science Civics Chapter 5 Popular Struggles and Movements, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 10 Social Science Civics Chapter 2 Federalism

These Solutions are part of NCERT Solutions for Class 10 Social Science. Here we have given NCERT Solutions for Class 10 Social Science Civics Chapter 2 Federalism.

TEXTBOOK EXERCISES

Question 1.
Locate the following States on a blank outline political map of India: Manipur, Sikkim, Chhattisgarh, and Goa.
Answer:
The states have been shown in the map on page P – 15.

Question 2.
Identify and shade three federal countries (other than India) on a blank outline political map of the world.
Answer:
Federal states — USA, Brazil, and Australia have been shown in the map on page P-16.

Question 3.
Point out one feature in the practice of federalism in India that is similar to and one feature that is different from that of Belgium.
Answer:
(1) Similar features: Distribution of powers –

In both the countries, power has been divided among the national government, state (provincial) government, and local governments (community govt, in Belgium).

• In Belgium,
  1. The regional governments have jurisdiction over transportation, public works, water policy, education, public health, and housing, etc.
  2. The community government has the power regarding cultural, educational, and language-related issues.
• In India, for example
  1. The legislative powers have been divided between the Union Govt and the State Governments.
  2. It contains three lists – Union list, State list, and Concurrent list.
  3. By the Act of 1992, the third tier e., local govts, have been granted more powers.

(2) Different features: Forms of government – In Belgium in addition to Central and State government, there is a third kind of government that is community government. This is elected by people belonging to one language community – Dutch, French, and German-speaking – no matter where they live. This government deals with cultural, educational, and language-related issues. In India, there is no such government.

In India, there is a three-tier government. The third government is the local government i.e., Panchayats at the village level and Municipalities at the town level. These bodies have been given powers by constitutional amendment in 1992.
Some of the provisions of the Act are as mentioned below :

• Mandatory to hold regular elections to local govt, bodies.
• Reservation of seats for SC/ST/OBC.
• Reservation of 1/3 seats for women.
• State Election Commission to hold elections.
• State govt, to share some powers.

Question 4.
What is the main difference between a federal form of government and a unitary one? Explain with an example.
Answer:
Under the federal system, generally, there are two sets of government i.e., national and state. Powers are divided between the two. For example in India, there are three lists – Union list, State list, and Concurrent list. The central or national government makes laws on the subjects in the Union List. These are subjects of national importance such as defense, foreign affairs and currency.

The state governments enact laws on the subjects included in the state list. These subjects are of state and local importance such as police, trade, agriculture and irrigation. Both the governments can enact laws on the subjects included in the concurrent list which includes subjects of common interest. These are education, forest, trade unions, and marriage etc.

On the other hand, under the unitary system, there is only one level of government at the national level. There are no provincial or state governments as we have in India. There is, therefore, no division of powers. The units or provincial government if any, are subordinate to the central government or national government as in England. The central or national government has all the powers.

Question 5.
State any two differences between the local government before and after the Constitutional amendment in 1992.                                                                                      ,
Answer:
A major step towards decentralization was taken in 1992. The Constitution was amended to make the third-tier of democracy more powerful and effective. Now it is constitutionally mandated to hold regular elections to local government bodies. Seats are reserved in the elected bodies and the executive heads of these institutions for the Scheduled Castes, Scheduled Tribes and Other Backward Classes.

At least one-third of all positions are reserved for women. An independent institution called the State Election Commission has been created in each State to conduct panchayat and municipal elections. The State governments are required to share some powers and revenue with local government bodies. The nature of sharing varies from State to State.

Question 6.
Fill in the blanks :

Since the United States is a (1)_________________________ type of federation, all the Constituent States have equal powers and States are (2)________________________ vis-a-vis the federal government. But India is a (3)_____________________ type of federation and some States have more power than others. In India, the (4)_______________________ govern­ment has more powers.
Answer:
(1) coming together (2) strong (3) holding together (4) central

Question 7.
Here are three reactions to the language policy followed in India. Give an argument and an example to support any of these positions.
Sangeeta: The policy of accommodation has strengthened national unity.
Arman: The language-based States have divided us by making everyone con­scious of their language.
Harish: This policy has only helped to consolidate the dominance of English over all other languages.
Answer:
The position held by Sangeeta that the policy of accommodation has strengthened national unity is correct. The Central Government agreed to continue the use of English along with Hindi for official purposes to avoid the Lankan kind of situation. Otherwise, the move­ment against Hindi would have taken a more ugly turn. The promotion of Hindi continues to be the official policy of the Government of India. Promotion does not mean that the Central Government can impose Hindi on states where people speak a different language. The flexibility shown by our leaders helped our country avoid the kind of situation that Sri Lanka finds itself in. Thus the policy of accommodation has strengthened national unity. Hindi is being used along with English for official purposes.

Question 8.
The distinguishing feature of a federal government is :
(a) National government gives some powers to the provincial government.
(b) Power is distributed among the legislature, executive, and judiciary.
(c) Elected officials exercise supreme power in the government.
(d) Governmental power is divided between different levels of government.

Question 9.
A few subjects in various Lists of the Indian Constitution are given here. Group them under the Union, State, and Concurrent Lists as provided in the table below :
Defence; B. Police; C. Agriculture; D. Education; E. Banking; F. Forests;  G. Communications; H. Trade; I. Marriages.

Union List
State List
Concurrent List

Answer:

1. Union List: Defence, Banking and Communications.
2. State List: Police, Agriculture and Trade.
3. Concurrent List; Education, Forests and Marriages.

Question 10.
Examine the following pairs that give the level of government in India and the powers of the government at that level to make laws on the subjects mentioned against each. Which of the following pairs is not correctly matched ?

(a) State government	State List
(b) Central government	Union List
(c) Central and State governments	Concurrent List
(d) Local governments	Residuary powers

Answer:
(d) Local governments — Residuary powers. It is not correctly matched because the residuary powers have been given to the Central Government.

Question 11.
Match List I with List-II and select the correct answer using the codes given below the lists :

List I	List II
1. Union of India	A. Prime Minister
2. State	B. Sarpanch
3. Municipal Corporation	C. Governor
4. Gram Panchayat	D. Mayor

 

	1	2	3	4
(a)	D	A	B	C
(b)	B	C	D	A
(c)	A	C	D	B
(d)	C	D	A	B

Answer:
(c) A, C, D, B.

Question 12.
Consider the following statements:

(a) In a federation, the powers of the federal and provincial governments are clearly demarcated.

(b) India is a federation because the powers of the Union and State Govern­ments are specified in the Constitution and they have exclusive jurisdiction on their respective subjects.

(c) Sri Lanka is a federation because the country is divided into provinces.

(d) India is no longer a federation because some powers of the States have been devolved to the local government bodies.

Which of the statements given above are correct?
(a) A, B, and C
(b) A, C, and D
(c) A and B only
(d) B and C only

We hope the NCERT Solutions for Class 10 Social Science Civics Chapter 2 Federalism help you. If you have any query regarding Extra Questions for Class 10 Social Science Civics Chapter 1 Power Sharing, drop a comment below and we will get back to you at the earliest.

NCERT Exemplar Solutions for Class 12 Biology chapter 4 Reproductive Health

These Solutions are part of NCERT Exemplar Solutions for Class 12 Biology. Here we have given NCERT Exemplar Solutions for Class 12 Biology chapter 4 Reproductive Health

Multiple Choice Questions

Question 1.
The method of directly injecting a sperm into ovum in assisted reproductive technology is called
(a) GIFT
(b) ZIFT
(c) ICSI   
(d) ET.
Answer:
(c) : ICSI or Intra Cytoplasmic Sperm Injection is one of the techniques of Assisted Reproductive Technology (ART) that helps couples to overcome their infertility. In ICSI, sperm is directly injected into ovum, in vitro to form zygote, which is implanted through ZIFT into woman.

Question 2.
Increased IMR and decreased MMR in a population will
(a) cause rapid increase in growth rate
(b) result in decline in growth rate
(c) not cause significant change in growth rate
(d) result in an explosive population/exp.
Answer:
(b) : If there is an increase in infant mortality rate (IMR) and decrease in maternal mortality rate (MMR), mothers are available to give birth to infants but the infants’ survival rate is low, which will ultimately hinder the growth rate of that particular population.

Question 3.
Intensely lactating mothers do not generally conceive due to the
(a) suppression of gonadotropins
(b) hypersecretion of gonadotropins
(c) suppression of gametic transport
(d) suppression of fertilisation.
Answer:
(a) : Presence of prolactin hormone in the blood of lactating mothers suppresses the release of gonadotropins (FSH and LH) from the pituitary gland. Gonadotropins are required for ovulation to occur. Thus, in the absence of, gonadotropins, ovum is not released and hence chances of fertilisation are nil upto 6 months following parturition (if the mother is regularly breast-feeding). Therefore, intensely lactating mothers do not generally conceive.

Question 4.
Sterilisation techniques are generally fool proof methods of contraception with least side effects. Yet, this is the last option for the couples because
(1) it is almost irreversible
(2) of the misconception that it will reduce sexual urge/drive
(3) it is a surgical procedure
(4) of lack of sufficient facilities in many parts of the country
Choose the correct option.
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (ii) and (iv)
(d) (i), (ii), (iii) and (iv)
Answer:
(d) : Sterilisation techniques are surgical procedures where, in males, vas deferens are cut and tied and in females, Fallopian tubes are cut and tied, preventing gamete transport.
Even though it is very effective it is often used as a last option by most couples. One, because it is almost irreversible. Second, because of some misconceptions like absence of ejaculation and lowering of sexual urge.Third, because it is a surgical procedure, there are certain risk of infection. Last but not least,
there are lack of sufficient facilities in many parts of our country (e.g., lack of hygiene, lack of qualified personnel etc.)

Question 5.
A national level approach to build up a reproductively healthy society was taken up in our country in
(a) 1950s
(b) 1960s
(c) 1980s
(d) 1990s
Answer:
(a) : The national level approach towards building a reproductively healthy society began with ‘family planning’ programmes in 1951. Over last 6 decades many other programmes have been started. In 2000, National Population Policy was launched and in 2005, National Rural Health Mission (NRHM) was launched, with the aim of revamping the public health services in rural areas. Janani Suraksha Yojana has also been launched which includes conditional cash transfer. Other improved programmes are also initiated with the term of ‘Reproductive and child Health Care’ (RCH). Launching a number of schemes will benefit only when people are aware of them and those working at the various stages of implementation are doing their work honestly and with right intention.

Question 6.
Emergency contraceptives are effective if used within
(a) 72 hrs of coitus
(b) 72 hrs of ovulation
(c) 72 hrs of menstruation
(d) 72 hrs of implantation.
Answer:
(a)

Question 7.
Choose the right one among the statements given below.
(a) lUDs are generally inserted by the user herself.
(b) lUDs increase phagocytosis reaction in the uterus.
(c) lUDs suppress gametogenesis.
(d) lUDs once inserted need not be replaced.
Answer:
(b) : Copper releasing IUDs (CuT, multiload) increase phagocytosis of sperms within the uterus and the Cu ions released suppress sperm motility and the fertilising capacity of sperms. The hormone releasing IUDs (progestaserf, LNG-20), make the uterus unsuitable for implantation and the cervix hostile to the sperms. IUDs are inserted and removed by trained doctors and they are ideal contraceptives for the females. IUDs, once inserted can be there for a long period of time (even years), especially, copper releasing IUDs. But eventually they need to be removed and replaced, as they are foreign to the body. Fertility returns, once IUDs are removed.

Question 8.
Following statements are given regarding MTP. Choose the correct options given below.
(1) MTPs are generally advised during first trimester.
(2) MTPs are used as a contraceptive method.
(3) MTPs are always surgical.
(4) MTPs require the assistance of qualified medical personnel.
(a) (ii) and (iii)
(b) (i) and (iii)
(c) (i) and (iv)   
(d) (i) and (ii)
Answer:
(c) : Voluntary termination of pregnancy before full term is called Medical Termination of Pregnancy (MTP). It is less riskier during first trimester (upto 12^th week) and requires assistance of qualified medical personnel. Surgical methods of termination of pregnancy include vacuum aspiration of the products of conception through an intra-uterine cannula, etc. It can also be induced using chemical drugs, e.g., mifepristone and prostaglandin. These drugs are taken only in the supervision of qualified medical personnel.

Question 9.
From the sexually transmitted diseases  mentioned below, identify the one which does not specifically affect the sex organs.
(a) Syphilis
(b) AIDS
(c) Gonorrhoea
(d) Genital warts
Answer:
(b) : AIDS (Acquired Immune Deficiency Syndrome) is caused by HIV (Human Immunodeficiency Virus, a retrovirus). It mainly affects the T-helper lymphocytes by infecting them. There is generally a long time lag between infection and occurrence of symptoms. Because of lowering of T-helper lymphocyte count, the person becomes vulnerable to infectious microorganisms, that otherwise, wouldn’t have caused any disease(opportunistic infection). A major example of this is tuberculosis. Weight loss also occurs in such persons.

Question 10.
Condoms are one of the most popular contraceptives because of the following reasons.
(a) These are effective barriers for insemination.
(b) They do not interfere with coital act.
(c) These help in reducing the risk of STDs.
(d) All of the above.
Answer:
(d)

Question 11.
Choose the correct statement regarding the ZIFT procedure.
(a) Ova collected from a female donor are transferred to the Fallopian tube to facilitate zygote formation.
(b) Zygote is collected from a female donor and transferred to the Fallopian tube.
(c) Zygote is collected from a female donor and transferred to the uterus.
(d) Ova collected from a female donor and transferred to the uterus.
Answer:
(None) : In test tube baby programme, ovum from donor female/wife and sperm from donor male/husband are induced to form zygote in the laboratory. The zygote is allowed to divide upto 8 blastomeres in the laboratory. Zygote or early embryo is then transferred into the Fallopian tube. This technique is called ZIFT (Zygote Intra Fallopian Transfer).

Question 12.
The correct surgical procedure as a contracep­tive method is
(a) ovariectomy
(b) hysterectomy
(c) vasectomy
(d) Casttation
Answer:
(c) : Vasectomy is a surgical contracep­tion method performed in males. In vasectomy a small part of the vas deferens is removed or tied up through a small cut on the scrotum.

Question 13.
Diaphragms are contraceptive devices used by the females. Choose the correct option from the statements given below.
(1) They are introduced into the uterus.
(2) They are placed to cover the cervical region.
(3) They act as physical barriers for sperm entry.
(4) They act as spermicidal agents.
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (iii) and (iv)
Answer:
(c) : Diaphragms are soft, hemispherical rubber cups fitted inside the vagina over the neck (cervix) of the uterus acting as physical barrier for sperm entry. When combined with the use of a chemical spermicide, they provide reliable contraception.

Very Short Answer Type Questions

Question 1.
Reproductive health refers only to healthy reproductive functions. Comment.
Answer:
According to WHO (World” Health Organisation), reproductive health means total well being of a person in all aspects of reproduction, i.e. physical, emotional, behavioral and social. It does not only refer to healthy reproductive functions.

Question 2.
Comment on the Reproductive and Child Health Care programme of the government to improve the reproductive health of the people
Answer:
RCH (Reproductive and Child Health Care) Programme aims at improving reproductive health of the society. Various measures undertaken by this programme include creating awareness among people about various reproduction related aspects, providing facilities and support for building up a reproductively healthy society, educating fertile couples about birth control measures, prenatal and postnatal care of mother and child, etc.

Question 3.
The present population growth rate in India is alarming. Suggest ways to check it.
Answer:
Ways to check present population growth rate are:
(1) Educating people by various audiovisual means about the advantages of small families.
(2) Making them aware of ill effects of overpopulation.
(3) Implementing family planning pro­grammes sincerely to achieve zero population growth.
(4) Increasing marriageable age limit.

Question 4.
STDscan be considered as self-invited diseases. Comment.
Answer:
Sexually Transmitted Diseases (STDs) can be considered as self-invited diseases because one could be free of these by following simple precautions. These are as follows:

• Avoid sex with unknown partners/multiple partners.
• Always use condoms during coitus.
• In case of doubt, one should go to a doctor for early detection and complete treatment.

Question 5.
Suggest the reproduction related aspects in which counselling should be provided at the school level.
Answer:
Introduction of sex education in schools is another step to give right information to the young minds about reproductive organs, accessory organs of reproduction, secondary sexual characters, adolescence and related changes, safe and hygienic sexual practices, sexually transmitted diseases, birth control methods etc. This knowledge will save them from myths and misconceptions about sex related aspects.

Question 6.
Mention the primary aim of the “Assisted Reproductive Technology” (ART) programme.
Answer:
ART (Assisted Reproductive Technology) programme assists the infertile couples to have children through some special techniques. It includes various programmes like test tube babies, ZIFT, GIFT, AIT, ICSI etc.

Question 7.
What is the significance of progesterone- estrogen combination as a contraceptive measure?
Answer:
Birth control pills like Mala D and Mala N have progesterone-estrogen combinations, and are commonly called combination pills. They inhibit ovulation and implantation.

Question 8.
Strict conditions are to be followed in medical termination of pregnancy (MTP) procedures. Mention two reasons.
Answer:
Two reasons for following strict condi­tions in medical termination of pregnancy (MTPs) are:

1. It is being misused to abort even the normal female foetuses.
2. MTP performed after first trimester i.e., 12 weeks of pregnancy becomes riskier as foetus becomes more deeply associated with uterine tissue of mother.

Question 9.
Males in whom testes fail to descend to the scrotum are generally infertile. Why?
Answer:
Sperms need slightly lower temperature than body temperature to survive, which is provided by scrotal sac. If testes fail to descend into scrotum, sperms will get killed at high temperature present in abdomen and the person will become infertile.

Question 10.
Mention two advantages of lactational amenorrhea as a contraceptive method.
Answer:
Two advantages of lactational amenorrhea as a contraceptive method are as follows:

1. During intense lactation after parturition, mother does not undergo menstruation and ovulation as high levels of prolactin suppresses ‘ secretion of gonadotropins from anterior pituitary.
2. No medicines or devices are used in this method thus, side effects are almost nil.

Short Answer Type Questions

Question 1.
Suggest some important steps that you would recommend to be taken to improve the reproductive health standards in India.
Answer:
Following measures are needed to be undertaken to improve the reproductive health standards in India :

1. Implementation of RCH (Reproductive and .Child Health Care) and family  planning programmes.
2. To follow child immunisation programme.
3. Introduction of sex education in schools to remove myths and misconceptions about sex related issues.
4. To impose statutory ban on amniocentesis and to check female foeticide.
5. To educate people about various health related programmes and family planning programmes.
6. To control sexually transmitted diseases.
7. Create fertility clinics to diagnose and treat disorders related to infertility.

Question 2.
The procedure of GIFT involves the transfer of female gamete to the Fallopian tube. Can gametes be transferred to the uterus to achieve the same result? Explain.
Answer:
The results will not be the same if gametes are introduced into the uterus, instead of Fallopian tube in the procedure of GIFT. This can be explained as follows. The Fallopian tube and its micro environment are ideal for fertilisation and early embryo development. The anatomy and physiology of Fallopian tube plays an important role in egg transport and fertilisation. Zygote formed as a result of fertilisation, divides to form embryo. Complex interactions take place between oviducal epithelium and the embryo. Human oviducal cells are known to secrete growth factors, cytokines and embryotrophic factors (ETFs) that enhance and support the development of the pre­implantation embryos. On the other hand, the uterine environment is not appropriate for the survival of the gametes, they may undergo degeneration or get phagocytosed in uterus and zygote formation will not be achieved.

Question 3.
Copper ions-releasing lUDs are more efficient than non-medicated methods. Why?
Answer:
Copper releasing IUDs like Cu-T, Cu-7, multi load 375 etc., are more efficient than non- medicated methods because non-medicated methods simply act as barriers for sperm entry into the reproductive tract of female and are not fool proof whereas copper ion releasing IUDs release Cu ions which suppress the sperm motility and fertilising capacity of the sperms and act as better contraceptives.

Question 4.
What are the probable factors that contributed to population explosion in India?
Answer:
Factors favouring population explosion are :

1. Lack of education in developing countries.
2. Lack of entertainment and gainful employ­ment in under-developed countries.
3. Early marriage, child labour.
4. Desire of male child, traditional religious beliefs etc.

Question 5..
Briefly explain IVE and ET. What are the conditions in which these methods are advised?
Answer:
In 1VF (In Vitro Fertilisation), fertilisation takes place outside the body of female in similar conditions as that in the body followed by E.T (Embryo Transfer). It is performed as follows:

1. Ova from the wife/donor female and sperms from husband/donor male are collected in hygienic manner.
2. Both ova and sperms are kept in culture medium under aseptic conditions.
3. Gametes are induced to fuse, and form zygote under simulated conditions.

In ET (Embryo Transfer) technique, developing embryo is transferred from culture medium to female reproductive tract. It is performed as follows:

1. Zygote is induced in culture medium to develop.
2. Endometrium is stimulated to be prepared for implantation.
3. Embryo is transferred to Fallopian tubes in 8 celled condition or transferred to uterus when it is at 16-32 celled stage. When in a woman normal conception is not possible because of blocked oviducts or spermicidal secretions in the vagina or when a woman cannot produce ova or man cannot produce sperms. In such conditions these methods are advised.

Question 6.
What are the advantages of natural methods of contraception over artificial methods?
Answer:
Natural methods of contraception include rhythm method, coitus interruptus and lactational amenorrhea. These methods do not involve use of any contraceptive or any chemical or surgery therefore, do not have any side effects. On the other hand, artificial methods of contraception which include IUDs, oral pills etc., have certain drawbacks. IUDs may cause occasional haemorrhage or infections. Combined oral pills generally have side effects like nausea, breast tenderness, weight gain, breakthrough bleeding and melasma etc.

Question 7.
What are the conditions in which medical termination of pregnancy is advised?
Answer:
The conditions in which medical termination of pregnancy is advised are as follows :

1. To get rid of unwanted pregnancy either due to unprotected intercourse or failure of the contraceptive used or rape.
2. If baby is suffering from an incurable and congenital developmental defect.
3. If continuation of pregnancy is harmful or even fatal either to mother, or to foetus or both.

Question 8.
Comment on the essential features required for an ideal contraceptive.
Answer:
An ideal contraceptive should be:

1. User friendly
2. Easily available and cheaper
3. Effective but also reversible
4. With no or least side effects
5. Should not interfere with the sexual act.

Question 9.
All reproductive tract infections RTIs are STDs, but all STDs are not RTIs. Justify with example.
Answer:
STDs are sexually transmitted diseases and include gonorrhoea, syphilis, genital warts, chlamydiasis, hepatitis B and AIDS. Hepatitis B and AIDS are not RTFs because they do not cause any infection in the reproductive tract but are spread through sexual means, whereas other diseases are STDs as well as RTIs.

Long Answer Type Questions

Question 1.
What are the Assisted Reproductive Techniques practiced to help infertile couples? Describe any three techniques.
Answer:
Assisted reproductive techniques are employed to diagnose and treat the infertile couples to have children. A few techniques are described as follows:

(1) Test tube babies : In this technique the fusion of ovum and sperm is done outside the body of the female to form a zygote Which is allowed to divide to form an embryo. This embryo is- then implanted in the uterus, where it develops into a foetus.

(2) Gamete Intra Fallopian Transfer (GIFT) : This method is vised in females, who can not produce ova, hut can provide suitable environment for fertilisation and further development of embryo in the oviducts. In such cases, ovum from the donor female is introduced into the Fallopian tube of such female. Such women accept sperms from their husbands during copulation.

(3) Intra Cytoplasmic Sperm Injection (ICSI) : It is another specialised technique to form an embryo in laboratory in which a I  sperm is directly injected into the ovum placed in a nutrient broth. The zygote or early embryo is later transferred to the Fallopian tube of woman by ZIFT.

Question 2.
Discuss the mode of action and advantages/disadvantages of hormonal contraceptives.
Answer:
Various hormonal contraceptives are:

1. Hormone releasing IUDs
2. Oral pills
3. Implants
4. Hormone injections

(1) Hormone releasing IUDs – Hormone  releasing IUDs include progestasert and LNG-20. They turn the cervix hostile to spermatozoa and bring changes in  the uterus making it unsuitable for implantation.

(2) Oral pills – They contain progestin  (progesterone like synthetic hormone) alone or a combination of synthetic progesterone and oestrogen. They inhibit the secretion of FSH and LH from anterior pituitary and inhibit ovulation and implantation. They also retard the entry of sperms in the uterus by changing the quality of cervical mucus.

(3) Subcutaneous implants – In this contraception method, six matchstick sized capsules containing synthetic progesterone are inserted under the skin of inner arm above the elbow. It acts similarly to oral contraceptives by blocking ovulation and thickening the cervical mucus to prevent sperm transport.

(4) Hormone injections – These are pro­ gesterone injections which are given once every 3 months and release hormone slowly and prevent ovulation. follows :
Various contraceptive techniques play significant role in checking the uncontrolled growth of human population. They are required to prevent pregnancy.

Disadvantages of hormonal contraceptives are as follows :
These hormone releasing contraceptives especially have many side effects. Use of IUDs possesses the risk of perforation of uterus and infection. Oral contraceptives can cause nausea, weight gain, breast tenderness, breakthrough bleeding, high blood pressure and melasma.

Question 3.
STDs are a threat to reproductive health. Describe any two such diseases and suggest preventive measures.
Answer:
Sexually transmitted disease (STDs) are threat to reproductive health. They are infectious, communicable and acquired diseases. They may lead to various complications like PID (pelvic inflammatory diseases), abortions, still birth, ectopic pregnancies, infertility or even cancer of reproductive tract. Some sexually transmitted diseases are discussed as follows :
(1) AIDS — It is caused by Human Immuno­deficiency Virus (HIV)
Symptoms – Fever, lethargy, pharyngitis, weight loss, nausea, headache, rashes etc.
HIV attacks helper T-lymphocytes. The patient gets immune deficiency and he/ she is unable to protect himself/herself against infections.

(2) Hepatitis B – It is caused by Hepatitis B virus (HBV).
Symptoms – Fatigue, jaundice, persistent low grade fever, rash and abdominal pain. It can also cause cirrhosis and possibly liver cancer.
STDs can be prevented by following ways:

• Use of condoms during coitus.
• Avoiding sex with unknown partners/ multiple partners.
• In case of doubt, consulting a qualified doctor for early detection and getting complete- treatment if diagnosed with disease.

Question 4.
Do you justify the statutory ban on amniocentesis in our country? Give reasons.
Answer:
Amniocentesis (along with sonography) is being misused to determine the sex of the foetus. Due to small family norm, along with religion and social practices, every family wants a male child. The female foetus is destroyed. This has resulted in decline in female population to less than 50 per 100 males in certain areas. Such an imbalance in sex ratio is bound to create social problems for the future generations. Therefore, statutory ban on the test is a rational move.

Question 5.
Enumerate and describe any five reasons for introducing sex education to school-going children.
Answer:
Introduction of sex education is necessary in schools because of the following reasons:

1. ,It will provide correct information about sex related matters and reproductive organs and will help removing all misconceptions and myths.
2. It can explain changes during adolescence. Help can be provided if there is any abnormality.
3. It can predict the changes in behaviour and prevent development of mental problems.
4. It will explain the harms of early sex and early marriage.
5. It will provide proper knowledge of cleanliness of genitalia and other organs.
6. It will provide correct information about sexually transmitted diseases.
7. It will give information about methods of family planning and hygienic sexual practices.

We hope the NCERT Exemplar Solutions for Class 12 Biology chapter 4 Reproductive Health help you. If you have any query regarding .NCERT Exemplar Solutions for Class 12 Biology chapter 4 Reproductive Health, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 10 Social Science Economics Chapter 4 Globalisation and the Indian Economy

These Solutions are part of NCERT Solutions for Class 10 Social Science. Here we have given NCERT Solutions for Class 10 Social Science Economics Chapter 4 Globalisation and the Indian Economy.

TEXTBOOK EXERCISES

Question 1.
What do you understand by globalization? Explain in your own words.
Answer:
Globalisation in today’s world has come to imply many things. It is the process by which the people of the world are unified into a single society and function together. This term is also often used to refer to economic globalization: the integration of national economies into the international economy through trade, foreign direct investments, capital flows, migration and the spread of technology.

Question 2.
What were the reasons for putting barriers to foreign trade and foreign investment by the Indian government? Why did it wish to remove these barriers?
Answer:
Barriers to foreign trade and foreign investment were put by the Indian government to protect domestic producers from foreign competition, especially when industries had just begun to come up in the 1950s and 1960s. At this time, competition from imports would have been a death blow to growing industries. Hence, India allowed imports of only essential goods.

Later, in the 1990s, the government wished to remove these barriers because it felt that domestic producers were ready to compete with foreign industries. It felt that foreign competition would in fact improve the quality of goods produced by Indian industries. This decision was also supported by powerful international organisations.

Question 3.
How would flexibility in labour laws help companies?
Answer:
Flexibility in labour laws would help companies in the ways mentioned below :

• It will help companies in being competitive and progressive.
• Flexibility in labour laws can help the companies to decrease their production cost by employing labourers only for short period of time when there is need instead of employing them for long period of time or yearly basis.
• By easing up on labour laws, company heads (managers) can negotiate wages and terminate employment, depending on market conditions. This will increase the competitiveness of the companies.
• The companies can ask the workers to work overtime when there is more pressure to complete the work.

Question 4.
What are the various ways in which MNCs set up or control the production in other countries?
Answer:
The various ways in which MNCs set up, or control, production in other countries are by buying out domestic companies or making the latter work for them. Sometimes, MNCs buy mass produce of domestic industries, and then sell it under their own brand name, at much higher rates, in foreign countries. MNCs look towards developing nations to set up trade because in such places, the labour and manufacturing costs are much lower.

Question 5.
Why do developed countries want developing countries to liberalise their trade and investment ? What do you think should the developing countries demand in return ?
Answer:
(1)

• World Trade Organisation which was started at the initiative of the developed countries says that all barriers of foreign trade and investment are harmful. It is supposed to allow free trade for all.
• In practice it is seen that the developed countries have unfairly retained trade barriers.
• On the other hand, WTO rules have forced the developing countries to remove trade barriers.
• Developed countries produce goods at a very low cost. The surplus goods are sold in
  other countries at a fairly higher price. This way they earn profits. So developed countries want
  developing countries to liberalise their trade and investment.

(2) The developed countries are biased against the developing countries. They have been

following wrong practices. The example is the debate on agriculture sector. In the USA, the share of agriculture in GDP is 1% and its share in total employment a tiny 0.5%. And this very small percentage of people who are engaged in agriculture in the US receive massive sums of money from the US government for production and for exports to other countries at low prices. This adversely affects farmers in these countries.

In view the above facts the developing countries should demand for fair trade practices to be followed by the developed countries under which they should stop giving subsidies to their agricultural sector. Trade barriers put unfairly should be removed. Only then there would be a free and fair trade in the world and the interest of the developing countries would be protected.

Question 6.
“The impact of globalisation has not been uniform.” Explain this statement.
Answer:
“The impact of globalisation has not been uniform”. The truth of this statement can be verified if we observe the impact of MNCs on domestic producers and the industrial working class. Small producers of goods such as batteries, capacitors, plastics, toys, tires, dairy products, and vegetable oil have been hit hard by competition from cheaper imports. Also, workers are now employed “flexibly” in the face of growing competition. This has reduced their job security. Efforts are now on to make globalisation “fair” for all since it has become a worldwide phenomenon.

Question 7.
How has the liberalization of trade and investment policies helped the globalization process?
Answer:
Liberalization has the following effects :

1. Goods can now be imported and exported easily.
2. Companies can set up factories and offices in other countries. For example, Ford Motors, an American company came to India in 1995 and set up a large plant near Chennai. This MNC not only produces cars for the Indian market, it also exports cars to other developing countries and exports car components for its many factories around the world.
3. Activities of many MNCs has increased foreign investment and foreign trade which has led to greater integration of production and markets across countries or globalisation process.

As a result of above, more and more countries are coming into closer contacts with each other due to MNCs. Therefore, liberalisation of trade and investment policies have helped in the globalisation process.

Question 8.
How does foreign trade lead to the integration of markets across countries ? Explain with an example other than those given here.
Answer:
Foreign trade leads to integration of markets across countries by the processes of imports and exports. Producers can make available their goods in markets beyond domestic ones via exports. Likewise, buyers have more choice on account of imports from other countries. This is how markets are integrated through foreign trade. For example, Japanese electronic items are imported to India, and have proved to be a tough competition for less-technologically-advanced companies here.

Question 9.
Globalisation will continue in the future. Can you imagine what the world would be like twenty years from now ? Give reasons for your answer.
Answer:
(a) Globalisation is a step towards the integration between countries through foreign trade and foreign investments by multinational corporations. Integration of production and integration of markets are the main objectives of globalisation. Rapid improvement in technol­ogy, liberalisation of trade and investment policies and the role of WTO has facilitated the process of globalisation.

(b) But in practice the globalisation has not benefited all the people. Moreover many rules of the WTO are biased against the developing countries. They are designed to force them to open their economies in the interest of the developed countries. For example, in the USA, the government gives massive sums of money to farmers whose share in total employment is only 0.5%, for production and for exports to other countries at abnormally low prices. Thus surplus farm products are sold in other country markets adversely affecting farmers in those countries. It is not a fair trade practice.

If such policies continue then the position of the developing countries may deteriorate. Many industries may not be able to compete and face closure. There will be less employment opportunities in the developing countries.

(c) However, efforts are being made to have a fair globalisation to ensure that its benefits are shared by all. Under these circumstances, the world after twenty years from now would bring people closer to each other. All the people would be benefited. The standard of living would improve and people would live a happier contented life than at present. But if the efforts for a fair globalisation fails then the condition of the developing countries of the world worsens because the regulations of the WTO will remain biased against the developing countries.

Question 10.
Supposing you find two people arguing: One is saying globalization has hurt our country’s development. The other is telling, globalisation is helping India de­velop. How would you respond to these arguments?
Answer:
Globalisation has hurt our country’s development because: firstly, it has led to the annihilation of small producers who face stiff competition from cheaper imports. Secondly, workers no longer have job security and are employed “flexibly”.
Globalisation is helping India develop on account of the following reasons: firstly, the competition it entails has led to rise in the quality of products in the market. Secondly, it has made available a wider variety of goods in the market, for the buyer to choose from. Now, imported goods are easily available alongside domestic products.

Question 11.
Fill in the blanks :

Indian buyers have a greater choice of goods than they did two decades back. This is closely associated with the process of (1)____________ . Markets in India are selling goods produced in many other countries. This means there is increasing (2)__________ with other countries. Moreover, the rising number of brands that we see in the markets might be produced by MNCs in India. MNCs are investing in India because
(3) ______ . While consumers have more choices in the market, the effect of rising (4)______ and (5)_________ has meant greater (6)___________ among the produc­tion
Answer:

1. globalisation
2. cooperation foreign
3. it has been beneficial for them
4. investment
5. foreign trade
6. competition

Match the following :

Question 12.

Answer:
(i)  (b) Garments, footwear, sports items
(ii)  (e) Trade barriers
(iii) (d)Tata Motors, Infosys, Ranbaxy
(iv) (c) Call centres
(v) (a) Automobiles.

Question 13.
Choose the most appropriate option :
(1) The past two decades of globalisation has seen rapid movements in
(a) goods, services, and people between countries.
(b) goods, services, and investments between countries.
(c) goods, investments, and people between countries.

(2) The most common route for investments by MNCs in countries around the world is to
(a) set up new factories.
(b) buy existing local companies.
(c) form partnerships with local companies.

(3) Globalisation has led to an improvement in living conditions
(a) of all the people.
(b) of people in developed countries.
(c) of workers in developing countries.
(d) none of the above.
Answer:

1. (b) goods, services and investments between countries.
2. (b) buy existing local companies.
3. (d) none of the above.

We hope the NCERT Solutions for Class 10 Social Science Economics Chapter 4 Globalisation and the Indian Economy help you. If you have any query regarding NCERT Solutions for Class 10 Social Science Economics Chapter 4 Globalisation and the Indian Economy, drop a comment below and we will get back to you at the earliest.

NCERT Exemplar Solutions for Class 12 Biology chapter 7 Evolution

These Solutions are part of NCERT Exemplar Solutions for Class 12 Biology. Here we have given NCERT Exemplar Solutions for Class 12 Biology chapter 7 Evolution

Multiple Choice Questions

Question 1.
Which of the following is used as an atmospheric pollution indicator?
(a) Lepidoptera
(b) Lichens
(c) Lycopersicon
(d) Lycopodium
Answer:
(b): Lichens are the association between specific ascomycetes and certain genera of either green algae or cyanobacteria. Lichens can be used as industrial pollution indicators. They never grow in area that are polluted.

Question 2.
The theory of spontaneous generation stated that
(a) life arose from living forms only
(b) life can arise from both living and non-living
(c) life can arise from non-living things only
(d) life arises spontaneously, neither from living nor from the non-living.
Answer:
(c) : The theory of spontaneous generation states that life originated from non-living things in a spontaneous manner. This concept was held by early Greek philosophers like Thales, Anaximander, Xanophanes,Empedocles, Plato, Aristotle, etc. In ancient Egypt, it was believed that the mud of the Nile could give rise to frogs, toads, snakes, mice and even crocodiles when warmed by the sun. Van Helmont (1577-1644) held that human sweat and wheat grains could give rise to organisms.

Question 3.
Animal husbandry and plant breeding programmes are the examples of
(a) reverse evolution
(b) artificial selection
(c) mutation
(d) natural selection.
Answer:
(b) : Animal husbandry and plant breeding programmes are the examples of artificial selection. Animals or plants with desirable characteristics are interbred with the aim of altering the genotype and producing a new strain of the organism for a specific purpose. Traditional breeding techniques have been supplemented by more recent methods of genetic engineering, genetic testing and embryo manipulation. Sequencing of genomes of commercially important animals and plant species has enabled the inheritance of desired genes to be monitored directly by molecular methods.

Question 4.
Palaentological evidences for evolution refer to the
(a) development of embryo
(b) homologous organs
(c) fossils
(d) analogous organs.
Answer:
(c) : Fossils are the remains or traces of any organism that lived in the geological past. In general only the hard parts of organisms become fossilised (e.g., bones, teeth, shells and wood) but under certain circumstances the entire organism is preserved. Fossil records such as number and nature of fossils in early rocks, distribution of fossils in successive strata, etc., have helped the scientists conclude that evolution has taken place from simple to complex forms in a gradual manner

Question 5.
The bones of forelimbs of whale, bat, cheetah and man are similar in structure, because
(a) one organism has given rise to another
(b) they share a common ancestor
(c) they perform the same function
(d) they have biochemical similarities.
Answer:
(b) : The bones of forelimbs of whale, bat, cheetah and man are similar in structure, because they are homologous organs. The organs which have the same fundamental structure but are different in functions are called homologous organs. These organs follow the same basic plan of organisation during their development. But in the adult condition, these organs are modified to perform different functions as an adaptation to different environments. The homologous structures are a result of divergent evolution.

Question 6.
Analogous organs arise due to
(a) divergent evolution
(b) artificial selection
(c) genetic drift
(d) convergent evolution.
Answer:
(d) : The organs which have similar functions but are different in their structural details and origin are called analogous organs. The analogous structures are the result of convergent evolution. The wings of an insect are analogous to wings of a bird. It is due to the fact that the basic structure of the wings of insects is different from the wings of bird. However, their function is similar.

Question 7.
(p+q)2 = p² + 2pq + q² = 1 represents an equation used in
(a) population genetics
(b) mendelian genetics
(c) biometrics
(d) molecular genetics.
Answer:
(a) : Hardy-Weinberg principle describes a theoretical situation in which a population is undergoing no evolutionary changes. According to Hardy-Weinberg principle, the balance in the relative numbers of alleles that is maintained within a large population over a period of time assuming that:

1. there is no genetic recombination
2. there is no natural selection
3. there is no gene migration
4. there is no mutation. In such a stable population, for a gene with two alleles A (dominant) and a (recessive), if the frequency of A is p and a is q, then the frequencies of the three possible genotypes (AA, Aa and aa) can be expressed by the Hardy-Weinberg equation; p² + 2pq + q² = 1.

Question 8.
Appearance of antibiotic-resistant bacteria is an example of
(a) adaptive radiation
(b) transduction
(c) pre-existing variation in the population
(d) divergent evolution.
Answer:
(c) : When a bacterial population encounters a particular antibiotic, those sensitive to it die. But some bacteria having favourable mutations become resistant to the antibiotic. Such resistant bacteria survive and multiply quickly. Soon the resistance providing genes become widespread and entire bacterial population becomes resistant.

Question 9.
Evolution of life shows that life forms had a trend of moving from
(a) land to water
(b) dryland to wet land
(c) fresh water to sea water
(d) water to land.
Answer:
(d) : Life’ originated in the ocean persumably about 4200 million years ago in precambrian era. The effect of electrical discharges and UV radiations on the mixture of methane, water, ammonia and hydrogen present in the sea gave rise to organic molecules like coacervates and microspheres. These protocells collected more substances forming cytoplasm and became first living beings. They were prokaryotic and chemoheterotrophic. When supply of existing organic molecules was exhausted, some heterotrophs evolved into autotrophs capable of synthesising food by chemosynthesis or photosynthesis. With + the advent of photoautotrophs, oxygen was added in sufficient amount in the primitive atmosphere. Eukaryotes originated in the ancient ocean, presumably about 1.5 billion years ago. These later on gave rise to complex forms. With the advent of oxygen, ozone layer was formed in the atmosphere which masked the land against the harmful UV radiations of sun and made it inhabitable. In the mean time, some complex plants could grow on land near water i.e., on boundary line and animal started visiting land, for food etc. Complex plants and animals developed jacketed sex organs and shelled eggs, respectively which reduced their dependence on water for completing their life cycles and they moved to land permanently. In this way, life forms moved from water to land.

Question 10.
Viviparity is considered to be more evolved because
(a) the young ones are left on their own
(b) the young ones are protected by a thick shell
(c) the young ones are protected inside the mother’s body and are looked after they are born leading to more chances of survival
(d) the embryo takes a long time to develop.
Answer:
(c)

Question 11.
Fossils are generally found in
(a) sedimentary rocks
(b) igneous rocks
(c) metamorphic rocks
(d) any type of rock.
Answer:
(a) : Sedimentary rocks are formed by gradual settling down or sedimentation of fragments or earth’s material in regions such as lake or sea. The animals or plants are preserved and fossilised when they are buried in the lava of volcano, in the ice, in an oil rich soil, in swamps, in desiccated deserts, in rocks, or under water, etc. Of all the media mentioned above the most common is water. Dead remains of aquatic animals and plants settle down at the bottom. Remains of terrestrial organisms are also brought to seas and big lakes by rivers and streams. Mud and sand settle down continuously at the bottom.

Sedimentation (deposition of layers) of mud and sand occurs. Fine mineral particles may penetrate the dead bodies. Decay and disintegration of organic remains take place to leave only the harder parts, impression, moulds, casts, etc. The sedimented mud and sand harden with time to form rocks.

Question 12.
FortheMN-blood group system, thefrequencies of M and N alleles are 0.7 and 0.3, respectively. The expected frequency of MN-blood group bearing organisms is likely to be
(a) 42%
(b) 49%
(c) 9%
(d) 58%.
Answer:
(a) : According to Hardy-Weinberg principle, the expected frequency of MN- blood group bearing organism is likely to be
p² + 2pq + q² = l
49 + .09 + 2x = 1
.58 + 2x = 1
2x = 1 – 59
= 42%

Question 13.
Which type of selection is industrial melanism, observed in moth, Biston betularia?
(a) Stabilising
(b) Directional
(c) Disruptive
(d) Artificial
Answer:
(b) : In directional selection, the population changes towards one particular direction. It means this type of selection
favours small or large-sized individuals and more individuals of that type will be present in next generation. The mean size, of the population changes. Example are evolution of DDT resistant mosquitoes, industrial melanism in peppered moth and evolution of giraffe.

Question 14.
The most accepted line of descent in human evolution is –
(a) Australopithecus—>Ramapithecus – ? Homo sapiens —»Homo habilis
(b) Homo erectus —> Homo habilis —> Homo sapiens
(c) Ramapithecus —» Homo habilis —> Homo erectus —> Homo sapiens
(d) Australopithecus —> Ramapithecus —> Homo erectus —> Homo habilis —> Homo sapiens.
Answer:
(c)

Question 15.
Which of the following is an example for link species?
(a) Lobe fish
(b) Dodo bird
(c) Sea weed
(d) Chimpanzee
Answer:
(a)

Question 16.
Match the scientists listed under Column ‘A’ with ideas listed under Column ‘B’.

Answer:
(a) A-(i); B-(iv); C-(ii); D-(iii)
(b) A-(iv); B-(i); C-(ii); D-(iii)
(c) A-(ii); B-(iv); C-(iii); D-(i)
(d) A-(iv); B-(iii); C-(ii); D-(i) miim (b)

Question 17.
In 1953, S. L. Miller created primitive earth conditions in the laboratory and gave experimental evidence for origin of first form of life from pre-existing non-living organic molecules. The primitive earth conditions created include
(a) low temperature, volcanic storms, atmosphere rich in oxygen
(b) low temperature, volcanic storms, reducing atmosphere
(c) high temperature, volcanic storms, non-reducing atmosphere
(d) high temperature, volcanic storms, reducing atmosphere containing CH4, NH3, etc.
Answer:
(d)

Question 18.
Variations during mutations of meiotic recombinations are
(a) random and directionless
(b) random and directional
(c) random and small
(d) random, small and directional.
Answer:
(a): Hugo de Vries (1901) put forward a theory of evolution, called mutation theory. The theory states that evolution is a jerky process where new varieties and species are formed by mutations (discontinuous variations) that function as raw material of evolution. Mutations appear all of a sudden. They become operational immediately.

Short Answer Type Questions

Question 1.
What were the characteristics of life forms that had been fossilised?
Answer:

1. Presence of hard parts in the body like bones, teeth, shell etc.
2. Buried in a medium where no oxidation of substances occur.

Question 2.
Did aquatic life forms get fossilise? If, yes where do we come across such fossils?
Answer:
Yes, aquatic life forms have better chances of getting fossilised, as their dead bodies are buried at the bottom of water in sedimentary rocks. They get exposed when the rocks come to the surface because of upheavals in the earth crust.

Question 3.
What are we referring to when we say ‘simple organisms’or’complex organisms’?
Answer:
Simple organisms are those organisms which show cellular level of body organisation,
i. e., their body is equivalent to a single cell. These organisms do not show ageing and natural death. As soon as the cell grows to maximum size, it divides to form daughter cells.
Complex organisms have higher level of body organisation as compared to unicellular organisms like tissue level, organ level and organ system level.

Question 4.
How do we compute the age of a living tree?
Answer:
We can compute the age of a living tree by counting the number of annual growth rings of tree. This technique is known as dendrochronology. It depends on the fact that trees in the same locality show a characteristic pattern of growth rings resulting from climatic conditions. Thus, it is possible to assign a definite date for each growth ring in living trees, and to use the ring patterns to date fossil trees or specimens of wood (e.g., used for building or objects on archaeological sites) with life spans that overlap those of living trees.

Question 5.
Give an example for convergent evolution and identify the features towards which they are converging.
Answer:
Tendrils in pea and cucurbits show convergent evolution because tendrils in both provide support to the plant (same function) but pea tendrils develop from leaves, whereas cucurbit tendrils are stem tendrils (different origin).

Question 6.
How do we compute the age of a fossil?
Answer:
Age of fossil can be computed by one of the following methods:

1. Radioactive carbon dating method
2. Uranium-lead method
3. Potassium-argon method
4. Electron spin resonance method.

Question 7.
What is the most important pre-condition for adaptive radiation?
Answer:
Most important pre-condition for adaptive radiation is that it should occur in s^me geographical area and is shown by different members of same ancestor. It is radiated to different habitats and develops different habits.

Question 8.
How do we compute the age of a rock?
Answer:
Age of rock can be determined by quantity of uranium and lead in the rocks and potassium-argon transformations.

Question 9.
When we talk of functional macromolecules (e.g. proteins as enzymes, hormones, receptors, antibodies etc), towards what are they evolving?
Answer:
Functional macromolecules are evolving towards creation of a complex organism. There are various evidences that are common to simple and complex forms of life which indicate common ancestry. E.g., histone protein tends to be well preserved among all eukaryotes with only one or two amino acids different.

Question 10.
In a certain population, the frequency of three genotypes is as follows:
Genotypes: BB Bb bb
Frequency: 22% 62% 16%
What is the likely frequency of B and b alleles?
Answer:
Frequency of allele B = 100% of BB + 50% of Bb
i. e., 22% + 31% = 53%
Frequency of allele b = 100 % of bb + 50% of Bb
i.e., 16% + 31% = 47%

Question 11.
Among the five factors that are known to affect Hardy-Weinberg equilibrium, three factors are gene flow, genetic drift and genetic recombination. What are the other two factors?
Answer:
The other two factors are mutation and natural selection.

Question 12.
What is founder effect?
Answer:
Founder effect is the phenomenon occurring when a population is founded by a small sample of the entire species, perhaps just a handful of individuals. Chance dictates that these founder members will be genetically unrepresentative of the species as a whole, and that the genetic make up of the new population will differ markedly from the main species population.

Question 13.
Who among the Dryopithecus and Ramapithecus was more man like?
Answer:
Ramapithecus was more man like in comparison to Dryopithecus, which was more ape-like.

Question 14.
By what Latin name the first hominid was known?
Answer:
As per the latest discoveries, Sahelanthropous tchadensis is considered the earliest hominid.

Question 15.
Among Ramapithecus, Australopithecus and Homo habilis – who probably did not eat meat?
Answer:
Ramapithecus probably did not eat meat. It was more man-like and lived on the tree tops but also walked on the ground. Its jaws and teeth were like those of humans. Its small canines and large molars suggest that Ramapithecus ate hard nuts and seeds like modern man.

Short Answer Type Questions

Question 1.
Louis Pasteur’s experiments, if you recall, proved that life can arise from only pre-existing life. Can we correct this as life evolves from pre¬existing life or otherwise we will never answer the question as to how the first forms of life arose? Comment.
Answer:
If we trace back the origin of first living organism, this fact will be revealed that life originated on early earth through physio- chemical processes in which atoms combined to form molecules which in turn reacted to produce inorganic and organic compounds.

These compounds then interacted to produce macromolecules which organised to form first living cells. Thus, first life form originated through abiogenesis. Once life originated, abiogenesis could not follow and new life forms then further evolved from pre-existing life (i.e., biogenesis).

Louis Pasteur in his experiments, disproved origin of life through abiogenesis and proved that life can arise from pre-existing life only. This statement holds true to its meaning but contradicts the mechanism of origin of first life form. Hence, it could be corrected as “life evolves from pre-existing life”.

Question 2.
The scientists believe that evolution is gradual. But extinction, part of evolutionary story, are ‘sudden’ and ‘abrupt’ and also group-specific. Comment whether a natural disaster can be the cause for extinction of species.
Answer:
Yes, natural disaster can lead to mass extinction of species from time to time, which is always ‘sudden’, ‘abrupt’ and ‘group specific’. For example extinction of dinosaurs is a good example of mass extinction triggered by a massive meteorite/asteroid impact. Asteroid impact was confirmed by the discovery of high concentrations of metal iridium in a thin layer of earth in almost all parts of the world as iridium is rare on earth and abundantly present in meteorites.

This natural disaster lead to the extinction of many contemporary species present on earth which included, non-avian dinosaurs, benthic foraminiferans, certain marine invertebrate groups etc.

Question 3.
Why is nascent oxygen supposed to be toxic to aerobic life forms?
Answer:
Nascent oxygen in highly reactive and can oxidise various biomolecules like DNA, RNA and proteins etc. If present in the cells of aerobic life forms, it can cause mutations and undesirable changes in their metabolic pathways. Therefore it has been considered as major toxic pollutant.

Question 4.
While creation and presence of variation is directionless, natural selection is directional as it is in the context of adaptation. Comment.
Answer:
The creation and presence of variations is directionless in regard that they occur randomly and spontaneously. Variations in organisms develop due to various reasons like genetic recombination, genetic drift, gene migration, mutations etc. All these variations are non-directional. As a result of variations, population becomes heterogeneous. Natural selection favours more adapted members oven less adapted ones and allows them to multiply at a faster rate to increase their population. This provides direction in a specific way towards evolution.

Question 5.
The evolutionary story of moths in England during industrialisation reveals, that’evolution is apparently reversible’ Clarify this statement.
Answer:
Peppered moth (Biston betularia) exists in two forms, white and melanic. Before industrialisation the trees were covered with whitish lichens. White moths could easily escape from their predators as they remained unnoticed in the surroundings. After industrialisation the bark of the trees got covered with black smoke and white moth were selectively picked up by the predators whereas the black ones escaped. Therefore, the population of white moths decreased. This showed that evolution is reversible and in a mixed population, those that can better adapt to the prevalant environmental conditions, survive and increase their population size but no variant is completely wiped out.

Question 6.
Comment on the statement that “evolution and natural selection are end results or consequences of some other processes but themselves are not processes”.
Answer:
All organisms possess enormous fertility. They multiply in geometric ratio, but the limited food supply, space and ecological niche begins intraspecific or interspecific struggle amongst them. For survival during struggle, organisms develop certain variations due to genetic recombinations, mutations etc., and become heterogenous. The organisms which have favourable variations would survive (survival of the fittest). Those who keep changing themselves according to the changing environment are selected by nature (natural selection). Selected organisms transfer their useful variations to next generation. Accumulation of continuous ’”variations generation after generation leads to evolution of new species. This clearly shows that evolution and natural selection are consequences of some other processes.

Question 7.
State and explain any three factors affecting allele frequency in populations.
Answer:
(1) Gene flow – It is also known as gene migration. It refers to the movement of alleles from one population to another as a result of interbreeding between members of the two population. The genes of two populations intermingle through breeding and result causes variations in the offspring.

(2) Genetic recombination – During sexual reproduction, fusion of male and female gametes takes place. These gametes are formed by reduction division or meiosis. Crossing over during meiosis leads to genetic variation as exchange of genetic material between non-sister chromatids of homologous chromosomes takes place. Hence, new association of alleles are formed in the gametes. Random fusion of gametes leads to genetic variations in the offspring.

(3) Mutations – Mutation is a sudden random change in genetic material of a cell. Somatic mutations affect the non- reproductive cells and are therefore restricted to a single organism but germline mutations which occur in reproductive cells (gametes) are transmitted to the offspring of organism. Mutations are caused by various chemicals or forms of radiations.

Question 8.
Gene flow occurs through generations. Gene flow can occur across language barriers in humans. If we have a technique of measuring specific allele frequencies in different population of the world, can we not predict human migratory patterns in pre-history and history? Do you agree or disagree? Provide explanation to your answer.
Answer:
Gene flow or gene migration refers to movement of alleles from one population to another as a result of interbreeding between members of two populations. Gene flow occurs through geographical barriers over generations. Changing gene frequencies would indicate that evolution is in progress. By studying specific allele frequencies of specific genes human migratory patterns and evolutionary trends in history and pre-history can be traced as gene migration (affected by human migration) contributes to changing gene frequency in an evolving population. Actually scientists are doing so, under Human Genome Project.

Question 9.
How do you express the meaning of words like race, breed, cultivars or variety?
Answer:
Race is a category used in the classification of organisms that consist of a group t>f individuals within a species that are geographically, ecologically, physiologically distinct from other members of the species e.g., negroid, mongoloid, etc. The term is frequently used in the same sense as subspecies. Breed is a group of animals similar in most characters and are related by descent, e.g., breeds of cow – Jersey, Holstein etc. Variety is a category used in the classification of plants and animals below the species level. A variety consists of a group of individuals that differ distinctly from but can interbreed with other varieties of the same species e.g., cabbage, cauliflower. Cultivar is a plant that has been developed and maintained by cultivation as a result of agricultural or horticultural practices. The term is derived from cultivated variety e.g., Pusa sem of flat beans.

Question 10.
When we say “survival of the fittest”, does it mean that
a. those which are fit only survive, or
b. those that survive are called fit? Comment.
Answer:
(a) In the struggle for existence, the individuals which have more favourable variations will have a competitive advantage over others which have less favourable or unfavourable variations. They are considered fit and thus survive and reproduce.

Question 11.
Enumerate three most characteristic criteria for designating a Mendelian population.
Answer:
Characteristic criteria for designating a Mendelian population are as follows :

1. Population must be large enough and there should be free flow of genetic materials among individuals through sexual reproduction.
2. Random mating of organisms takes place.
3. There should be either nil or negligible migration.

Question 12.
“Migration may enhance or blur the effects of selection” Comment.
Answer:
Migration involves entry or exit of some members of a species into or from an area. It may cause improvement of race if there is entry of individuals with more desirable genes, or may cause deterioration of race if there is entry of individuals with undesirable traits or exit of individuals with desirable traits. Hence, migration may enhance or blur the effects of selection.

Long Answer Type Questions

Question 1.
Name the law that states that the sum of allelic frequencies in a population remains constant. What are the five factors that influence these values?
Answer:
Hardy-Weinberg Principle states that sum of allele frequencies in a population is stable and remains constant from generation to generation i.e., the gene pool (total genes and their alleles in a population) remain constant. The five factors, called evolutionary agents, which influence the allele frequencies in a population are :

1. Gene flow – When migration of a section of population to another place occurs, gene frequencies change in the original as well as new population. New alleles are added to the new population and these are lost from the old population. Hence, gene flow changes the allele frequency in a population.
2. Genetic drift – It refers to the elimination of genes of certain traits when a section of population migrates or dies of natural calamity. It affects the gene frequency of a population.
3. Genetic recombinations – During sexual reproduction, fusion of male and female gametes takes place. The gametes are formed by reduction division or meiosis. Crossing over during meiosis leads to genetic variation as exchange of genetic material between non-sister chromatids of homologous chromosomes takes place and new association of alleles are formed in the gametes. The offsprings formed by fusion of gametes show new combination of traits.
4. Mutations – The sudden heritable change in genetic material which is directionless is called mutation. It alters the genetic make up of an individual.
5. Natural selection – It is the phenomenon by which some members of a population having desirable or favourable traits are favoured and survive to produce new offspring.

Question 2.
Explain divergent evolution in detail. What is the driving force behind it?
Answer:
Similarity in basic structural plan and developmental origin and difference in appearance and functioning of those structures due to adaptations of different needs is called divergent evolution. The driving force behind it is adaptation to new habitat and the prevailing environmental conditions there. As the original population increases in size, it spreads out from its centre of origin to exploit new habitats and food resources. In time this results in a number of populations each adapted to this particular habitat. Eventually these populations differ from each other sufficiently to become new species.
A good example of this process is the evolu tion of the Australian marsupials into species adapted as carnivores, herbivores, burrowers, fliers, etc.

Question 3.
You have studied the story of Pepper moths in England. Had the industries been removed, what impact could it have on the moth population? Discuss.
Answer:
Peppered moth, Biston betularia lives in all parts of England. In the population of peppered moth, two variants exist – dark or melanic and light coloured. Before industrialisation, light coloured moths were prevelant because they blended with the lichen covered bark of trees and remained unnoticed by predatory birds. The melanic moths were easily detected and preyed upon by predatory birds. Hence, the population of light coloured moth was much more as compared to dark  or melanic moth. With industrialisation, the pale tree trunks became more and more blackened due to industrial smoke and soot. As a result the light moths stood out in contrast to their background, increasing the possibility of being easily detected and eaten by their predators, such as birds, in much greater number than the dark melanic variety. Decrease in the number of light moths and increase in the number of dark moths was the ultimate result.

Therefore, evolution favoured the melanic moths to reproduce more successfully for their adaptation in the polluted areas of England. If the industries are removed the area will again become free of pollution leading to growth of lichens. As stated earlier, light coloured moth would easily camouflage with a light background and dark variants would be spotted easily by predators and eaten more frequently. Hence, the population of light coloured moth will again increase.

Question 4.
What are the key concepts in the evolution theory of Darwin?
Answer:
Key concepts in the evolution theory of Darwin are as follows:
(1) Overproduction or enormous fertility: Living beings have an innate ability of producing their own progeny for the continuity of race.

(2) Struggle for existence : According to Darwin, individuals multiply in geometric ratio whereas space and food remain almost constant.

(3) Variations and heredity : The everlasting competition among the organisms compells them to change according to the conditions so that they can utilise the natural resources and can survive successfully. According to Darwin, the variations are gradual (continuous) and those which are helpful in the adaptations of an organism towards its surroundings would be passed on to the next generation, while the others disappear.

(4) Survival of the fittest or Natural selection: During the struggle for existence only those individuals could survive which exhibit such variations that are more beneficial in facing the hardships and rigours of environment or which change to adapt themselves to the changing conditions. This is known as natural selection.

(5) Origin of species : Natural selection results in modification of traits within a lineage which over a period of time can bring about evolution.

Question 5.
Two organisms occupying a particular geographical area (say desert) show similar adaptive strategies. Taking examples, describe the phenomenon.
Answer:
The phenomenon indicated in the question is convergent evolution wherein organisms which are not closely related, evolve similar traits independently as a result of adaptation to similar environment. There is specific type of environment existing in every geographical area. The environmental factors influence all the organisms living in that area. This can be explained by following examples :
(1) Pectoral fins of sharks and flippers of dolphins are analogous organs. Pectoral fins of sharks are not pentadactyle. The flippers of dolphins are pentadactyle. Thus, basic structure of pectoral fins of sharks and flippers of dolphins are different but both are useful in swimming.

(2) Stings of honey bee and scorpion are analogous structures. The sting of honey bee is a modification of its ovipositor (structure that helps in egg laying) while that of scorpion is modified last abdominal segment. Stings of both arthropods perform similar function.

(3) Leaves are plant organs specialised for photosynthesis. However, there are plants where the leaves are modified or reduced in response to hot and dry environment. The function of leaves is then taken over by other organs like stipules (e.gLathyrus aphaca), petiole (e.g., Acacia auriculiformis) and stem branches (e.g, Ruscus, Asparagus). They are analogous amongst them as well as to the leaves.

Question 6.
We are told that evolution is a continuing phenomenon for all living things. Are humans also evolving? Justify your answer.
Answer:
New researches suggest that human beings are also evolving like all other organisms. By studying specific evolutionary trends in various human characters it can be provfed that human beings are evolving :
(1) Lactose tolerance : Historically the gene that regulated human’s ability to digest lactose was shut down as infants are weaned off of their mother’s breast milk. However, adult human in regions of Africa and Northern Europe developed the ability to tolerate lactose in their diets as recent as 5,000 or 6,000 years ago due to mutations.

(2) Wisdom teeth : Our ancestors had much bigger jaws than we do. Today our jaws are much smaller and wisdom teeth may not erupt in some. Estimates say that they will disappear in the coming population.

Question 7.
Had Darwin been aware of Mendel’s work, would he been able to explain the origin of variations. Discuss.
Answer:
Mendel proposed certain laws of heredity which form the basis of inheritance of characters. He is commonly called ‘father of genetics’ because of his contribution to genetics. Darwin’s theories explain the survival of the fittest, but does not explain the mode of arrival of fittest. He did not explain about any particular substance for inheritance of continuous useful variations from one generation to the other. Whereas Mendel stated that inheritance of characters is particulate and every character is of discrete units called factors (now called alleles). If Darwin had been aware of Mendel’s work, he could have been able to explain the origin of variations and their inheritance in the light of changes in the factors of Mendel.

We hope the NCERT Exemplar Solutions for Class 12 Biology chapter 7 Evolution help you. If you have any query regarding .NCERT Exemplar Solutions for Class 12 Biology chapter 7 Evolution, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 10 Social Science Civics Chapter 4 Gender Religion and Caste

These Solutions are part of NCERT Solutions for Class 10 Social Science. Here we have given NCERT Solutions for Class 10 Social Science Civics Chapter 4 Gender Religion and Caste.

TEXTBOOK EXERCISES

Question 1.
Mention different aspects of life in which women are discriminated or disadvantaged in India.
Answer:
Sexual difference is biological but gender difference is sociological. Women on the basis of gender have always been discriminated in almost all the societies of the world including India. Ours is a male-dominated patriarchal society. Women face disadvantage, discrimination, and oppression in various ways as mentioned below :

(1) Different aspects of life in which women are discriminated or disadvantaged in India are as given below :

1. Education :
   • Women are deprived of equal access to education. Thus, the literacy rate among women is only 54 percent as compared to 76 percent among men.
   • A smaller proportion of girl students go for higher education because in spite of their better performance than boys, they drop out as parents prefer to spend their resources for their son’s education,
   • They do not want to spend equally on their sons and.daughters.
2. Discrimination in job opportunities and remuneration or salary :
   • The number of women on highly paid jobs is less than men.
   • Women are discriminated in job opportunities as well as in appointment among highly paid and valued jobs,
   • Under Equal Wages Act, equal wages should be paid for equal work. In practice almost in every sphere, women are paid less than men, even when both do exactly the same work,
   • On average an Indian woman works one hour more than an average man every day. Yet much of her work is not paid and therefore often not valued.
3. Preference for sons: Even now in many parts of India, parents prefer to have sons, There are cases where a girl child is aborted before she is born. Due to sex-selective abortion, the sex-ratio has declined from 927 in 2001 to 850 or 800 in some places.
4. Cases of harassment, exploitation, and violence: Women are exploited by their employers. They are sexually assaulted at homes. They are not safe during their journey at night. They are subjected to various forms of domestic violence such as beating and harassment.

Question 2.
State different forms of communal politics with one example each.
Answer:
The most common expression of communalism is in everyday beliefs. These routinely involve religious prejudices, stereotypes of religious communities and belief in the superiority of one’s religion over other religions. This is so common that we often fail to notice it, even when we believe in it.

A communal mind often leads to a quest for political dominance of one’s own religious community. For those belonging to the majority community, this takes the form of majoritarian dominance. For those belonging to the minority community, it can take the form of a desire to form a separate political unit.

Question 3.
State how caste inequalities are still continuing in India.
Answer:
Caste has not disappeared from contemporary India. Some of the older aspects of caste have persisted. Even now most people marry within their own caste or tribe. Untouchability has not ended completely, despite constitutional prohibition. The effects of centuries of advantages and disadvantages continue to be felt today. The caste groups that had access to education under the old system have done very well in acquiring modern education as well. Those groups that did not have access to education or were prohibited from acquiring it have naturally lagged behind. That is why there is a disproportionately large presence of ‘upper caste’ among the urban middle classes in our country. Caste continues to be closely linked to economic status.

Question 4.
State reasons to say that caste alone cannot determine election results in India.
Answer:
The caste alone cannot determine election results in India due to the reasons as mentioned
below :

1. No majority of one caste in a constituency: No parliamentary constituency in the country has a clear majority of one single caste. So, every candidate and party needs to win the confidence of more than one caste and community to win elections.
2. No votes of one cast/community: No party wins the votes of all the voters of a caste or community. When people say that caste is a vote bank of one party, it usually means that a large proportion of the voters from that caste vote for that party.
3. Candidates from the same caste :
   • Many political parties may put up candidates from the same caste if that caste is believed to dominate the electorate in a particular constituency.
   • In addition to this some voters have more than one candidate from their caste while many voters have no candidate from their caste. All these factors divide the voters between two or more candidates.
4. The ruling party and the sitting members frequently lose elections in our country. This could not have happened if all castes and communities were frozen in their political preferences.
5. Sometimes the voters have strong attachment to political parties which is often stronger than their attachment to their caste or community.
6. People within the same caste or community may have different interests depending on their economic condition. Rich and poor or men and women from the same caste often vote very differently.
7. Lastly people make their own assessment about the performance of their leaders and this differs with one another.
   Thus it can be concluded that caste alone cannot determine election results in India.

Question 5.
What is the status of women’s representation in India’s legislative bodies?
Answer:
In India, the proportion of women in the legislature has been very low. For example, the percentage of elected women members in Lok Sabha has never reached even 10 percent of its total strength. Their share in the state assemblies is less than 5 percent. In this respect, India is among the bottom group of nations in the world. India is behind the averages for several developing countries of Africa and Latin America. In the government, cabinets are largely all-male even when a woman becomes the Chief Minister or the Prime Minister.

Question 6.
Mention any two constitutional provisions that make India a secular state.
Answer:
Two constitutional provisions that make India a secular state are given below :

1. There is no official religion in India. Our Constitution does not give a special status to any religion like Islam in Pakistan, Buddhism in Sri Lanka and Christianity in England. State observes an attitude of neutrality and impartiality towards all religions.
2. The Constitution provides to all persons and communities freedom to profess, practice and propagate any religion or not to follow any.

Question 7.
When we speak of gender divisions, we usually refer to :
(a) Biological difference between men and women.
(b) Unequal roles assigned by society to men and women.
(c) Unequal child sex ratio. .
(d) Absence of voting rights for women in democracies.
Answer:
(b) Unequal roles assigned by society to men and women.

Question 8.
In India, seats are reserved for women in
(a) Lok sabha
(b) State legislative assemblies
(c) Cabinets
(d) Panchayati Raj bodies
Answer:
(d) Panchayati Raj bodies

Question 9.
Consider the following statements on the meaning of communal politics: Communal politics is based on the belief that :
A. One religion is superior to that of others.
B. People belonging to different religions can live together happily as equal citizens.
C. Followers of a particular religion constitute one community.
D. State power cannot be used to establish the domination of one religious group over others.
Which of the statements is/are correct?
(a) A, B, C and D
(b) A, B and D
(c) A and C
(d) B and D
Answer:
(c) A and C

Question 10.
Which among the following statements about India’s Constitution is wrong?
(a) prohibits discrimination on grounds of religion.
(b) gives official status to one religion.
(c) provides to all individuals the freedom to profess any religion.
(d) ensures the equality of citizens within religious communities.
(b) gives official status to one religion.
Answer:
(b) gives official status to one religion.

Question 11.
Social divisions based on ……………… are peculiar to India.
Answer:
caste

Question 12.
Match List I with List-II and select the correct answer using the codes given below the Lists:

	List I	List II
1.	A person who believes in equal rights and opportunities for women and men	A. Communalist
2.	A person who says that religion is the principal basis of community	B. Feminist
3.	A person who thinks that caste is the principal basis of community	C. Secularist
4.	A person who does not discriminate others on the basis of religious beliefs	D. Castiest

 

	1	2	3	4
(a)	B	C	A	D
(b)	B	A	D	C
(c)	D	C	A	B
(d)	C	A	B	D

Answer:
(b) B, A, D, C is the correct answer.

We hope the NCERT Solutions for Class 10 Social Science Civics Chapter 4 Gender Religion and Caste help you. If you have any query regarding NCERT Solutions for Class 10 Social Science Civics Chapter 4 Gender Religion and Caste, drop a comment below and we will get back to you at the earliest.

NCERT Exemplar Solutions for Class 12 Biology chapter 6 Molecular Basis of Inheritance

These Solutions are part of NCERT Exemplar Solutions for Class 12 Biology. Here we have given NCERT Exemplar Solutions for Class 12 Biology chapter 5 Principles of Inheritance and Variation

Multiple Choice Questions

Question 1.
In a DNA strand, the nucleotides are linked together by
(a) glycosidic bonds
(b) phosphodiester bonds
(c) peptide bonds
(d) hydrogen bonds.
Answer:
(b) : A nucleotide has three components – nitrogenous base, a pentose sugar (ribose in case of RNA and deoxyribose for DNA) and a phosphate group. There are two types of nitrogenous bases – purines (adenine and guanine) and pyrimidines (cytosine, thymine and uracil). A nitrogenous base is linked to the pentose sugar through a N-glycosidic linkage to form a nucleoside. When a phosphate group is linked to 5′ -OH of a nucleoside through phosphoester linkage, a correspondingnucleotide is formed. The nucleotides are linked through 3′ – 5′ phosphodiester linkage to form a dinucleotide.

Question 2.
A nucleoside differs from a nucleotide. It lacks the
(a) base
(b) sugar
(c) phosphate group
(d) hydroxyl group.
Answer:
(c) : A purine or pyrimidine base joined with a pentose sugar, either ribose or deoxyribose, is a nucleoside. A nucleotide is a nucleoside with one or more phosphate groups attached to the sugar.

Question 3.
Both deoxyribose and ribose belong to a class of sugars called
(a) trioses
(b) hexoses
(c) pentoses  
(d) polysaccharides.
Answer:
(c) : Pentose sugar is a sugar molecule with five carbon ring structure. Both ribose and deoxyribose are pentoses, the latter is formed by deoxygenation of the former at one carbon atom.

Question 4.
The fact that a purine base always paired through hydrogen bonds with a pyrimidine base leads to, in the DNA double helix
(a) the antiparallel nature
(b) the semi-conservative nature
(c) uniform width throughout DNA
(d) uniform length in all DNA.
Answer:
(c) : In DNA chain, the base pairs on the two strands are complementary and a specific purine pairs with a specific pyrimidine. This makes the two chains uniformly (2nm) thick. A larger sized purine lies opposite to the smaller-sized pyrimidine i.e., A pairs with T and C pairs with G giving uniform width throughout DNA.

Question 5.
The net electric charge on DNA and histones is
(a) both positive
(b) both negative
(c) negative and positive, respectively
(d) Zero
Answer:
(c) : DNA is much more organised in eukaryotic chromatin and is associated with a variety of proteins, most prominent of which are histones. Histones are rich in the basic amino acid residues lysines and arginines. Both these amino acid residues carry positive charges in their side chains. Thus, histones are positively charged. Histones are organised to form a unit of eight molecules called as histone octamer. The negatively charged DNA is wrapped around the positively charged histone octamer to form a structure called nucleosome.

Question 6.
The promoter site and the terminator site for transcription are located at
(a) 3′ (downstream) end and 5′ (upstream) end, respectively of the transcription unit
(b) 5′ (upstream) end and 3′ (downstream) end, respectively of the transcription unit
(c) the 5′(upstream) end
(d) the 3′ (downstream) end.
Answer:
(b)

Question 7.
Which of the following statements is the most appropriate for sickle cell anaemia?
(a) It cannot be treated with iron supple­ments.
(b) It is a molecular disease.
(c) It confers resistance to acquiring malaria.
(d) All of the above
Answer:
(d) : Sickle cell anaemia is an autosomal hereditary disorder in which the erythrocytes become sickle shaped under oxygen deficiency, such as during strenuous exercise and at high altitudes. The disorder or disease is caused by the formation of an abnormal haemoglobin molecule called haemoglobin-S. Sickle cell trait protects against malaria. Several studies have suggested that, sickle haemoglobin might get in the way of Plasmodium parasite infecting RBCs, reducing the number of parasites that actually infect the host cell and thus confer some protection against the disease.

Question 8.
One of the following is true with respect to AUG:
(a) It codes for methionine only.
(b) It is also an initiation codon.
(c) It codes for methionine in both prokaryotes and eukaryotes.
(d) All of the above
Answer:
(d) AUG has dual functions : it acts as initiation codon and also codes for methionine (both in prokaryotes and eukaryotes, although formylated in prokaryotes).

Question 9.
The first genetic material could be
(a) protein
(b) carbohydrates
(c) DNA
(d) RNA.
Answer:
(d) : The first genetic material could be RNA. Evidences suggest that, metabolism, splicing and translation all have evolved around RNA. The first biocatalysts were also RNAs. Even now, some enzymes are made of RNAs, e.g., ribozyme. Gradually during evolution, genetic storage function of RNA was taken over by DNA as RNA being single stranded was more reactive, hence unstable. DNA being double stranded with complementary strands is not only more stable but also resists changes as it has evdlved a process of repair. For biocatalysis, RNA was replaced by protein enzymes. The latter were more stable, efficient and occur in many forms.

Question 10.
With regard to mature mRNA in eukaryotes
(a) exons and introns do not appear in the mature RNA
(b) exons appear but introns do not appear in the mature RNA
(c) introns appear but exons do not appear in the mature RNA
(d) both exons and introns appear in the mature RNA.
Answer:
(b) : Eukaryotic transcripts possess extra segments called introns or intervening sequences or noncoding sequences. They do not appear in mature or processed RNA because post transcriptional processing of the transcript includes splicing i.e., the’ process of removal of introns and fusion of exons to form functional RNAs.

Question 11.
The human chromosome with the highest and least number of genes in them are respectively
(a) chromosome 21 and Y
(b) chromosome 1 and X
(c) chromosome 1 and Y
(d) chromosome X and Y.
Answer:
(c) : Chromosome 1 has 2968 genes while Y-chromosome has 231 genes which respectively are the maximum and minimum number of genes present in a chromosome.

Question 12.
Who amongst the following scientists had no contribution in the development of the double helix model for the structure of DNA?
(a) Rosalind Franklin
(b) Maurice Wilkins
(c) Erwin Chargaff
(d) Meselson and Stahl
Answer:
(d)

Question 13.
DNA isa polymer of nucleotides whicharelinked to each other by 3′-5’phosphodiester bond. To prevent polymerisation of nucleotides, which of the following modifications would you choose?
(a) Replace purine with pyrimidines.
(b) Remove/Replace 3′ OH group in deoxyribose.
(c) Remove/Replace 2′ OH group with some other group in deoxyribose.
(d) Both ‘b’ and ‘c’.
Answer:
(b) : If 3′ OH group is removed/replaced in deoxyribose, there will be no formation of phosphodiester bonds which is formed between 3′ hydroxyl (OH) group of one nucleotide and 5′ phosphate of the other, and hence polymerisation of nucleotides will be prevented.

Question 14.
Discontinuous synthesis of DNA occurs in one strand, because
(a) DNA molecule being synthesised is very long
(b) DNA dependent DNA polymearse catalyses polymerisation only in one direction (5′->3’)
(c) it is a more efficient process
(d) DNA ligase has to have a role.
Answer:
(b) :The DNA-dependent DNA poly­merases catalyse polymerisation only in one direction, that is 5′ —> 3′. Consequently, on one strand (the template with polarity 3′ —> 5′), the replication is continuous in 5′ —» 3′ direction, while on the other (the template with polarity 5′ —» 3′), it is discontinuous. A RNA primer is added the 3′ end of the opened region of 5′ —» 3′ strand and on this primer, a short stretch of DNA is synthesised in 5′ —> 3′ direction. Then again, when further uncoiling occurs then a new primer is added at 3′ end which is elongated, and the process continues. These discontinuously synthesised fragments are later joined by the enzyme DNA ligase.

Question 15.
Which of the following steps in transcription is catalysed by RNA polymerase?
(a) Initiation
(b) Elongation
(c) Termination
(d) All of the above
Answer:
(d) : There is single DNA-dependent RN Apoly merase that catalyses transcription of all types of RNA in bacteria. RNA polymerase binds to promoter and initiates transcription (initiation). It uses nucleoside triphosphates as substrate and polymerises them in a template dependent fashion following the rule of complementarity. It somehow also facilitates opening of the helix and continues elongation. Only a short stretch of the prepared RNA remains bound to the enzyme.Once the polymerase reaches the terminator region, the nascent RNA falls off, so also the RNA polymerase. This results in termination of transcription. The RNA polymerase alone is only capable to catalyse the process of elongation. It associates transiently with initiation factor(o) and termination factor(р)  to initiate and terminate the transcription respectively. Association with these factors alters the specificity of the RNA polymerase to either initiate or terminate. In eukaryotes, several initiation factors and termination factors along with three types of RNA polymerase each polymerising a specific RNA perform these functions.

Question 16.
Control of gene expression takes place at the level of
(a) DNA replication
(b) transcription
(c) translation
(d) none of the above
Answer:
(b & c) : Regulation of gene expression refers to a very broad term that may occur at various levels. In eukaryotes, the gene expression can be regulated at transcriptional level, post transcriptional processing level, during transport of mRNA from nucleus to the cytoplasm, and at translational level whereas in prokaryotes, control of the rate of transcriptional initiation is the predominant site for control of gene expression.

Question 17.
Regulatory proteins are the accessory proteins that interact with RNA polymerase and affect its role in transcription. Which of the following statements is correct about regulatory proteins?
(a) They only increase expression.
(b) They only decrease expression.
(c) They interact with RNA polymerase but do not affect the expression.
(d) They can act both as activators and as repressors.
Answer:
(d) : In a transcription unit, the activity of RNA polymerase at a given promoter is regulated by interaction with accessory proteins, which affect its ability to recognise start sites. These regulatory proteins can act both positively (activators) and negatively (repressors).

Question 18.
Which was the last human chromosome to be completely sequenced:
(a) Chromosome 1
(b) Chromosome 11
(c) Chromosome 21
(d) Chromosome X
Answer:
(a) : The sequencing of chromosome 1 was completed in May 2006. This was the last of the 24 human chromosomes (22 autosomes and X and Y) to be sequenced.

Question 19.
Which of the following are the functions of RNA?
(a) It is a carrier of genetic information from DNA to ribosomes synthesising polypeptides.
(b) It carries amino acids to ribosomes.
(c) It is a constituent component of ribosomes.
(d) All of the above.
Answer:
(d) : mRNA carries genetic information from DNA to ribosomes for synthesising polypeptide chains. fRNA carries amino acids to ribosomes attached to mRNA for translation. rRNA, is a vital component of ribosomes.

Question 20.
While analysing the DNA of an organism, a total number of 5386 nucleotides were found out of which the proportion of different bases were: Adenine = 29%, Guanine = 17%, Cytosine = 32%, Thymine = 17%. Considering the Chargaff’s rule it can be concluded that
(a) it is a double stranded circular DNA
(b) it is a single stranded DNA
(c) it is a double stranded linear DNA
(d) no conclusion can be drawn.
Answer:
(b) : It cannot be a double stranded DNA because as per Chargaff’s rule for a dsDNA, the ratios between adenine and thymine, and guanine and cytosine are constant and equal. Hence, it is a ssDNA.

Question 21.
In some viruses, DNA is synthesised by using RNA as template. Such a DNA is called
(a) A-DNA
(b) B-DNA
(c) c DNA
(d) rDNA.
Answer:
(c) : DNA synthesis on RNA template occurs in retroviruses or RNA viruses. They have RNA as their genetic material. When they infect a host cell, they first synthesise DNA on RNA template which is known as cDNA or complementary DNA. This cDNA then continues the process of infection.Regulatory proteins are the accessory proteins that interact with RNA polymerase and affect its role in transcription. Which of the following statements is correct about regulatory.

Question 22.
If Meselson and Stahl’s experiment is continued for four generations in bacteria, the ratio of ^,5N/¹⁵N: ¹⁵N/¹⁴N: ¹⁴N/¹⁴N containing DNA in the fourth generation would be
(a) 1:1:0
(b) 1:4:0
(c) 0:1:3
(d) 0:1:7
Answer:
(d) : In Meselson and Stahl’s experiment, parent DNA isolated from E.coli is grown in heavy ¹⁵N medium. It was then put in light ^,4N medium.Then, when replication occurs the new strand synthesised would have ^l4N. The process can be represented as follows:

Question 23.
If the sequence of nitrogen bases of the coding strand of DNA in a transcription unit is 5′ – AT G A A T G – 3′, the sequence of bases in its RNA transcript would be
(a) 5′-AUGAAUG-3′
(b) 5′-UACUUAC-3′
(c) 5′-C All UC AU-3′
(d) 5′ – G U A A G U A – 3′.
Answer:
(a) : The sequence of bases in RNA transcript is similar (not complementary) to the coding DNA strand except that in RNA, uracil is present in place of thymine. So, the correct sequence of bases is:
5′ – AUGAAUG – 3′

Question 24.
The RNA polymerase holoenzyme transcribes
(a) the promoter, the structural gene and the terminator region
(b) the promoter and the terminator region
(c) the structural gene and the terminator region
(d) the structural gene only.
Answer:
(d) : Transcription involves three separate processes : initiation, elongation and termination. Initiation begins when the RNA polymerase binds to the promoter which serves only as a target site for binding of the RNA polymerase and is not transcribed. Each gene contains a specific promoter region for guiding the beginning of transcription. This is followed by region of gene (structural gene) that is transcribed and ends with a terminator that stops transcription and is not transcribed.

Question 25.
If the base sequence of a codon in mRNA is 5′-AUG-3′, the sequence of fRNA pairing with it must be
(a) 5′- UAC – 3′
(b) 5′-CAU-3′
(c) 5’-AUG-3′
(d) 5′- GUA – 3′.
Answer:
(b) : The first base of anticodon in 5′ – 3′ direction binds with the third base in codon (reading in 5′ – 3′ direction). Thus, if the base sequence in codon of mRNA is 5′- AUG – 3′, the complementary anticodon will be 3′-UAC – 3′ or 5′- CAl – 3′.

Question 26.
The amino acid attaches to the fRNA at its
(a) 5′-end
(b) 3′-end
(c) Anticodon site
(d) DHU loop.
Answer:
(b) : fRNA has an anticodon loop that has bases complementary to the code, it also has an amino acid acceptor site at which it binds to amino acids. This site lies at the 3′ end opposite the anticodon. fRNAs are specific for each ahrino acid.

Question 27.
To initiate translation, the mRNA first binds to
(a) the smaller ribosomal sub-unit,
(b) the larger ribosomal sub-unit
(c) the whole ribosome
(d) no such specificity exists.
Answer:
(a) : The cellular factory responsible for synthesising proteins is the ribosome. The ribosome consists of structural RNAs and about 80 different proteins. It has two subunits, a large subunit and a small subunit. To start translation, mRNA should bind to small ribosomal unit.

Question 28.
In E. coli, the lac operon gets switched on when
(a) lactose is present and it binds to the repressor
(b) repressor binds to operator
(c) RNA polymerase binds to the operator
(d) lactose is present and it binds to RNA polymerase.
Answer:
(a) : The repressor of the operon is synthesised (all-the-time-constitutively) from the / gene. The repressor protein binds to the operator region of the operon and prevents RNA polymerase from transcribing the operon. In the presence of an inducer, such as lactose or allolactose, the repressor is inactivated by interaction with the inducer. This allows RNA polymerase access to the promoter and transcription proceeds. Thus, the lac operon gets switched on.

Very Short Answer Type Questions

Question 1.
What is the function of histones in DNA packaging?
Answer:
Maim Histones are positively charged basic proteins which help in condensation of DNA. Negatively charged DNA gets wrapped around positively charged histone octamer to form nucleosome.

Question 2.
Distinguish between heterochromatin and euchromatin. Which of the two is transcriptionally active?
Answer:
Heterochromatin is thicker, densely packed, dark stained part of chromatin. Euchromatin is thinner, loosely packed lightly stained part of chromatin. Transcriptionally active part is euchromatin.

Question 3.
The enzyme DNA polymerase in coli is a DNA dependent polymerase and also has the ability to proofread the DNA strand being synthesised. Explain. Discuss the dual polymerase.
Answer:
DNA polymerase serves as a dual polymerase which serves two functions. It primary function is to add nucleotides according to the template strand in 5′ —> 3′ direction. It simultaneously proof reads the newly formed double strand, as it passes through the polymerase molecule. If the wrong base is inserted, the bond is unstable and spontaneous melting of the newly formed stretch occurs. The new strand gets exposed to the 3′ exonuclease site of the enzyme which removes the mismatched base and some additional nucleotides from the 3’ end. Then, the polymerase activity is continued again. This reduces the chances of error in DNA replication from about one in a million to about one in a hundred million base pairs.

Question 4.
What is the cause of discontinuous synthesis of DNA on one of the parental strands of DNA? What happens to these short stretches of synthesised DNA?
Answer:
New DNA strand is always formed in 5′-3′ direction during DNA replication, over DNA template with 3′-5′ direction. When DNA opens during replication, 3′-5′ strand forms a continuous strand called leading strand. The other template strand with 5′-3′ orientation produces a new short strand over the fork every time when it opens. These short segments are called Okazaki fragments. These segments join together with DNA ligases and form lagging strand.

Question 5.
Given below is the sequence of coding strand of DNA in a transcription unit:
3’AATGCAGCTATTAGG-5′ Write the sequence of
(a) its complementary strand
(b) the mRNA
Answer:
(a) Sequence of complementary strand will be : 5′ -TTACGTCGATAATCC3′
(b) Sequence of mRNA will be : 3′ – A A U G C A G C U A U U A G G 5′

Question 6.
What is DNA polymorphism? Why is it important to study it?
Answer:
Variation at genetic level arisen due to mutations, is called polymorphism. Such variations are unique at particular site of DNA. The polymorphism (variations) in DNA sequences is the basis of genetic mapping and DNA fingerprinting.

Question 7.
Based on your understanding of genetic code, explain the formation of any abnormal haemoglobin molecule. What are the known consequences of such a change?
Answer:
Haemoglobin is made of four polypeptide chains, two a-chains-which are 141 amino acids long and two (3-chains which are 146 amino acids long. In case of sickle cell anaemia, a fault occurs at the sixth amino acid in the (5-chain. The, amino acid should be glutamic acid. In HbS however, it is replaced by valine.

Question 8.
Sometimes cattle or even human beings give birth to their young ones that are having extremely different sets of organs like limbs/ position of eye(s) etc. Comment.
Answer:
Development of organs in an organism is regulated by expression of different sets of genes in a definite sequence in an orderly manner. Any disturbance in co-ordination ‘         and expression of genes will lead to abnormal  i. organ formation.

Question 9.
In a nucleus, the number of ribonucleoside triphosphates is 10 times the number of deoxy ribonucleoside triphosphates, but only deoxy ribonucleotides are added during the DNA replication. Suggest a mechanism.
Answer:
Recent studies show that there is a region in the active site cleft of the polymerase enzyme that monitors the 2′ and 3′ substituents of the incoming nucleotide and identifies the sugar component. It ensures that only deoxyribonucleotides are picked up during  replication from the nuclear pool.

Question 10.
Name a few enzymes involved in DNA replication other than DNA polymerase and ligase. Name the key functions for each of them.
Answer:

1. DNA helicase which stimulates the separation of the two strands.
2. Topoisomerase which changes the degree of supercoiling in DNA by cutting one or both strands, which forms
3. Primase which forms RNA primer strands on single-stranded DNA templates.

Question 11.
Name any three viruses which have RNA as the genetic material.
Answer:

1. Tobacco Mosaic Virus
2. Human Immunodeficiency Virus
3. Influenza Virus

Short Answer Type Questions

Question 1.
Define transformation in Griffith’s experiment. Discuss how it helps in the identification of DNA as the genetic material.
Answer:
In 1928, Frederick Griffith performed the transformation experiment using Streptococcus pneumoniae. When he injected heat killed, virulent S strain along with non-virulent, live R strain in mice, then the mice died. It showed that something from dead S strain transformed the non-virulent R strain into virulent one. This phenomenon was called transformation by him. Transformation is the phenomenon by which the transforming principle (as named by Griffith), isolated from one type of cell, when introduced into another type, is able to bestow some of the properties of the former to the latter. This discovery started the quest for identification of this transforming principle. Avery, MacLeod and McCarty later purified biochemicals (proteins, DNA, RNA, etc.) from the heat-killed S cells to see which ones could transform live R cells into S cells. They discovered that DNA alone (neither proteins nor RNAs) from S bacteria caused R bacteria to become transformed. They discovered that protein-digesting enzymes (proteases) and RNA-digesting enzymes (RNases) did not affect transformation. Digestion with DNase did inhibit transformation, suggesting that the DNA caused the transformation.

Question 2.
Who revealed biochemical nature of the transforming principle? How was it done?
Answer:
Refer answer 1.

Question 3.
Discuss the significance of heavy isotope of nitrogen in the Meseison and Stahl’s experiment.
Answer:
¹⁵N is not a radioactive isotope. It is a heavy isotope of N and can be separated from ¹⁴N by density gradient centrifugation. This helped Meseison and Stahl to prove that DNA replicates semiconservatively. Meseison and Stahl extracted bacterial DNA and centrifuged it in caesium chloride solution. Depending on the mass of the molecule, the DNA would settle out at a particular point in the tube. They first grew Escherichia coli bacteria in a medium containing heavy isotope ¹⁵N for several generations.

The ¹⁵N bacteria were then transferred to a growth medium containing the normal, lighter isotope of nitrogen, ¹⁴N, where they reproduced by cell division. Extracts of DNA from the first generation offspring were shown to have a lower density, since half the DNA was made up of the original strand containing ¹⁵N and the other half was made up of the new strand containing ¹⁴N. At succeeding generation times, the DNA extracts were found to separate at lower densities indicating that have a lower proportion of ^,5N as more ¹⁴N had incorporated into the bacterial DNA. This was conclusive evidence for the semi­conservative method of DNA replication.

Question 4.
Define a cistron. Giving examples, differentiate between monocistronic and polycistronic ‘transcription unit.
Answer:
Cistron is a length of DNA that contains the information for coding a specific polypeptide chain or codes for a functional RNA molecule (i.e., mRNA, transfer RNA or ribosomal RNA).

Monocistronic transcription unit is a type of messenger RNA that can encode only one polypeptide per RNA molecule. In eukaryotic cells, virtually all messenger RNAs are monocistronic.

Polycistronic transcription unit is a type of messenger RNA that can encode more than one pqlypeptide separately within the same RNA molecule. Bacterial messenger RNA is generally polycistronic.

Question 5.
Give any six features of the human genome.
Answer:
Features of the human genome are as follows:

• Human genome has 3.1647 billion nucleotide base pairs.
• The average gene size is 3000 base pairs. The largest gene is that of Duchenne muscular dystrophy on X-chromosome. It has 2.4 million (2400 kilo) base pairs. (3-globin and insulin genes are less than 10 kilobases.
• The human genome consists of about 30,000 genes. Previously, it was estimated to contain 80,000 to 100,000 genes.
• Chromosome 1 has 2968 genes while Y-chromosome has 231 genes. They are the maximum and minimum genes for the human chromosomes.
• The function of over 50% of discovered genes is unknown.
• Less than 2% of the genome represents structural genes that code for proteins.

Question 6.
During DNA replication, why is it that the entire molecule does not open in one go? Explain replication fork. What are the two functions that the monomers (dNTPs) play?
Answer:
Whole of DNA does not open in one stretch due to very high energy requirement. The point of separation proceeds slowly towards both the directions in DNA strands. In each direction, it gives the appearance of Y-shaped structure called replication fork. Deoxyribonucleoside triphosphates (dNTPs) serve dual purposes. In addition to acting as substrates, they provide energy for polymerisation reaction (the two terminal phosphates in a deoxynucleoside triphosphates are high-energy phosphates, same as in case of ATP).

Question 7.
Retroviruses do not follow central dogma. Comment.
Answer:
Retroviruses follow reverse of central dogma. Temin and Baltimore reported that double stranded RNA of Rous Sarcoma
Virus (RSV) operates a central dogma reverse (inverse flow of information). RNA of these viruses first synthesises DN A through reverse transcription or feminism. DNA then transfers information to RNA which takes part in translation of coded information to form polypeptide. The mechanism is characteristic of retroviruses, e.g., HIV.

Question 8.
In an experiment, DNA is treated with a compound which tends to place itself amongst the stacks of nitrogenous base pairs. As a result of this, the distance between two consecutive bases increases from 0.34 nm to 0.44 nm. Calculate the length of DNA double helix (which has 2 x 10⁹ bp) in the presence of saturating amount of this compound.
Answer:
In the given question, the distance between two consecutive base pairs is 0.44 nm (0.44 x 10⁹m).
Total number of base pair is 2 x 10⁹ bp.
Length of DNA double helix is calculated by multiplying the total number of bp with distance between two consecutive bp i.e., 2 x 10⁹ bp x 0.44 x 10^-9 m/bp.Therefore, length of DNA double helix is 0.88 m.

Question 9.
What would happen if histones were to be mutated and made rich in acidic amino acids such as aspartic acid and glutamic acid in place of basic amino acids such as lysine and arginine?
Answer:
Acidic amino acids are negatively charged. DNA is also negatively charged, Therefore, acidic amino acids will not be able to hold DNA over them. This will lead to failure of packaging of DNA material resulting no chromatin formation.

Question 10.
Recall the experiments done by Frederick Griffith, Avery, MacLeod and McCarty, where DNA was speculated to be the genetic material. If RNA, instead of DNA was the genetic material, would the heat killed strain of Pneumococcus have transformed the R-strain into virulent
Answer:
RNA is labile and prone to degradation Recall the experiments done by Frederick Griffith, Avery, MacLeod and McCarty, where DNA was speculated to be the genetic material. If RNA, instead of DNA was the genetic material, would the heat killed strain of Pneumococcus have transformed the R-strain into virulent form.

Question 11.
You are repeating the Hershey-Chase experiment and are provided with two isotopes ³²P and ¹⁵N (in place of ³⁵S in the original experiment). How do you expect your results to be different?
Answer:
³²P is a radioactive isotope but ¹⁵N is not. ¹⁵N is heavier isotope of nitrogen. Even if it can be detected, ¹⁵N will not be able to differentiate between protein and genetic material because it will get incorporated both in DNA as well as proteins. Therefore, the experiment will not give any conclusive result.

Question 12.
There is only one possible sequence of amino acids when deduced from a given nucleotide sequence. But multiple nucleotide sequences can be deduced from a single amino acid sequence. Explain this phenomena.
Answer:
There are 64 triplet codons and only 20 amino acids. Some amino acids are coded by more than one codons. Except tryptophan (UGG) and methionine (AUG) which have single codon each, all other amino acids involved in protein synthesis have more than one codon. In degenerate codons, mostly the first two nitrogen bases are similar while the third one is different. Thus as a codon codes only for a specific amino acid we can deduce a single amino acid sequence from a nucleotide sequence. But, as an amino acid can be coded by multiple codons thus many nucleotide sequences can be coded from a given amino acid sequence.

Question 13.
A single base mutation in a gene may not ‘always’ result in loss or gain of function. Do you think the statement is correct? Defend your answer.
Answer:
Sometimes single base mutation may not cause formation of new amino acid. It occurs usually when change’ occurs in third base of triplet codon, e.g. G G A can be replaced by GGU, GGC, and GGG without affecting the incorporation of amino acid glycine. Such mutations are called silent mutations and do not cause any change in the phenotype of the organism.

Question 14.
A low level of expression of lac operon occurs at all the time. Can you explain the logic behind this phenomenon?
Answer:
The lac operon synthesises the permease enzyme which is responsible for transporting lactose into the cell. If permease will not be present, then the lactose cannot enter the cell and cannot act as inducer for lac operon. Hence, a low level of expression of lac operon is always maintained in the cell, so that whenever lactose is present, it can enter the cell and induce lac operon.

Question 15.
How has the sequencing of human genome opened new windows for treatment of various genetic disorders. Discuss amongst your classmates.
Answer:
Human genome sequencing has been very useful in treatment of genetic disorders, such as:

• It has been found that more than 1200 genes are responsible for common human cardiovascular diseases, endocrine diseases (like diabetes), neurological disorders (like Alzheimer’s disease), cancer and many more. Thus, the medicines that specifically target these genes can be made.
• Efforts are in progress to determine genes that will change cancerous cells into normal.
• All the genes or transcripts in a particular t tissue, organ or tumor can be analysed toknow the cause or effect produced in it.

Question 16.
The total number of genes in humans is far less (< 25,000) than the previous estimate (up to 1,40,000 gene). Comment.
Answer:
At the start of genome sequencing project, scientists estimated that human genome has about 1,40,000 genes. The number gradually fell down to 30,000 and finally has been found to be between 20,000 to 25,000. The estimates were so high because scientists have found E.coli (single celled) to have about 4300 genes and Caenorhabditis elegans (about 1000 cell) to have about 19000 genes. Thus, asper the assumption that the more complex an organism the more is number of genes, the human gene number has been estimated to be more than one lakh. But, number of genes has no relationship with complexity of organism. Besides, it also has been found that genome size and gene number is unrelated because only 2% of the genome actually consists of structural genes, rest 98% is non-coding DNA.

Question 17.
Now, sequencing of total genome is getting less expensive day by the day. Soon it may be affordable for a common man to get his genome sequenced. What in your opinion could be the advantage and disadvantage of this development?
Answer:
Advantages of genome sequencing are as follows:

1. It will provide information about genetic abnormalities.
2. There will be possibility of transfer of certain desired genes to the progeny.
3. Proneness to certain diseases will make a person avoid certain factors causing those diseases.
4. Information about timing of normal appearance of degenerative diseases and how to postpone them can be gathered.
5. Metobolic defects can be taken care of. Disadvantages of genome sequencing are as follows:
6. Knowing about disease much in advance may lead the person under depression.
7. People will become keen to improve their genetic constitution.

Question 18.
Would it be appropriate to use DNA probes such as VNTR in DNA fingerprinting of a bacteriophage?
Answer:
Bacteriophages do not have repetitive sequences like VNTR in their genome. Bacterial genome is small in size and with all coding sequences. Therefore DNA finger­printing cannot be done in bacteriophage.

Question 19.
During in vitro synthesis of DNA, a researcher used 2′, 3′ – dideoxycytidine triphosphate as raw nucleotide in place of 2′ -deoxycytidine. What would be the consequence?
Answer:
2′-3′ dideoxycytidine triphosphate cannot form an ester bond necessary for chainformation of DNA, where as 2′ deoxycytidine phosphate can develop such bond. Chain formation of DNA or polymerisation of DNA will stop due to presence of 2′-3′- dideoxycytidine.

Question 20.
What background information did Watson and Crick have made available for developing a model of DNA? What was their contribution?
Answer:
The information already available with them for developing a model of DNA was –

1. Erwin Chargaff’s generalisations about DNA structure e., the purine and pyrimidines are always in equal amounts A + G = T + C, and the amount of adenine is always equal to that of thymine and the amount of guanine is always equal to that of cytosine A = T and G = C.
2. X Ray diffraction pictures of crystalline DNA produced by Maurice Wilkins and Rosalind Franklin.

Contributions of Watson and Crick to this background data are:

1. DNAis a double helical structure with two chains running in antiparallel direction.
2. Complementary base pairing rule
3. Semi conservative replication
4. Mutations occur due to tautomeric changes in nitrogen bases.

Question 21.
What are the functions of (i) methylated guanosine cap, (ii) poly-A “tail” in a mature RNA?
Answer:
Methylated guanosine cap helps in attachment of mRNA to smaller subunit of ribosome during initiation of translation process.
Poly-A-tail provides longevity to mRNA’s life. Tail length and longevity of mRNA are positively correlated.

Question 22.
Do you think that the alternative splicing of exons may enable a structural gene to code for several isoproteins from one and the same gene? if yes, how? if not, why so?
Answer:
Alternative splicing is a controlled process which causes different mRNAs to be produced from a single gene by including some exons in one mRNA under some conditions, while including other exons under other conditions. This greatly increases the number of proteins that can be encoded by < 2$,000 functional genes of the genome. This alternative splicing of exons is sex-specific, tissue-specific and even developmental stage- specific. By alternative splicing of exons, a single gene may encode for several isoproteins and/or proteins of similar class.

Question 23.
Comment on the utility of variability in number of tandem repeats during DNA fingerprinting.
Answer:
Number and type of tandem repeats are specific for every individual. An individual gets them from two parents, but are unique for the individual. Therefore, they can be used to identify the individuals, and their relatives by comparing the repeats using DNA finger printing process.

Long Answer Type Questions

Question 1.
Give an account of Hershey and Chase experiment. What did it conclusively prove? If both DNA and proteins contained phosphorus and sulphur do you think the result would have been the same?
Answer:
Hershey and Chase experiment is based on the fact that phosphorus is present in DNA but not in the protein, and similarly sulphur is present in proteins but not in DNA. They incorporated radioactive isotope of phosphorus (³²P) into phage DNA and that of sulphur (³⁵S) into proteins of a separate phage culture. These phage types were used independently to infect the bacterium Escherichia coli. After some time, this mixture was agitated in a blender to separate the empty phage capsids from the surface of bacterial cells and the two were separated by centrifugation. Hershey and Chase showed that when ³²P was used, all radioactivity was associated with bacterial cells and if followed, appeared in the progeny phage.
However, when ³⁵S was used, all radioactive material was limited to phage ‘ghosts’ (empty viral protein coats). These results indicated that the DNA of the bacteriophage and not the protein enters the host, where viral replication takes place. Therefore, DNA is the genetic material of T₂ bacteriophage. It directs protein coat synthesis and allows replication to occur. If both DNA and proteins contained phosphorus and sulphur, they could not differentiate or separate protein and DNA and could not have concluded anything.

Question 2.
During course of evolution why DNA was chosen over RNA as genetic material? Give reasons by first discussing the desired criteria in a molecule that can act as genetic material and in the light of biochemical differences between DNA and RNA.
Answer:
A molecule that can act as a genetic material must fulfill the following criteria:

• It should be able to generate its replica (replication).
• It should chemically and structurally be stable.
• It should provide the scope for slow changes (mutation) that are required for evolution.
• It should be able to express itself in the form of ‘Mendelian Characters’.

Though RNA is known to be the genetic material in some viruses and early cells, it is not a very suitable genetic material because 2′ – OH group present in every nucleotide of RNA is a reactive group. It means RNA is highly reactive, labile and easily degradable. RNA functions as an enzyme and is, therefore, reactive and unstable.Uracil present in RNA is less stable as compared to thymine (methyl uracil) of DNA.

Being unstable, RNA mutates at a much faster rate, that is why RNA viruses have shorter life span and mutate and evolve very fast. Such ‘rapid changes are harmful to higher forms of life.

DNA is the genetic material of most of the organisms because

• DNA is chemically less reactive and structurally more stable as its nucleotides are not exposed except when they have to express their effect or to be replicated.
• They are comparatively more stable than RNA. Heat which killed bacteria in Griffith’s experiment did not destroy their DNAs.
• Presence of thymine in DNA instead of uracil, provides stability to DNA.
• Hydrogen bonding between purines and pyrimidines and their stacking make DNA more stable for storage of genetic information.
• DNA is capable of undergoing slow mutations required of genetic material.
• It has a power of repairing.
  Since DNA is more stable while RNA is more reactive, both the types of nucleic acids have been retained in genetic expression. DNA which is stable enough not to change with different stages of life cycle, age or with change in metabolism of the organism, is retained as better genetic material for the storage of genetic information. It expresses genetic information by protein synthesis through RNA which is more reactive, exposed for quicker action of protein synthesising machinery and thus is better for the transmission of genetic information.

Question 3.
Give an account of post transcriptional modifications of a eukaryotic mRNA.
Answer:
Transcription in eukaryotes occurs within the nucleus. The primary mRNA transcript is longer and localised in the nucleus, where it is also called heterogenous nuclear RNA (/mRNA) or pre-mRNA.
The mRNA is processed from the primary RNA transcript in a process called maturation. Initially, at the 5′ end, a cap (consisting of 7-methyl guanosine or 7 mG) and a tail of poly A at the 3′ end are added. The cap is a chemically modified molecule of guanosine triphosphate (GTP). The primary mRNAs are made up of two types of segments; non¬coding introns and the coding exons. The introns are removed by a process called RNA splicing. Of a pair of small nuclear ribonucleoprotein (snRNPs), one binds to 5′ splice site and the other to 3′ splice site. A spliceosome forms because of interaction between snRNPs and other proteins. This spliceosome uses energy of ATP to cut the RNA and to release the introns. The enzyme ligase joins two adjacent exons to produce mature mRNA.

Question 4.
Discuss the process of translation in detail.
Answer:
The process of decoding of the message from mRNA to protein with the help of fRNA, ribosome and enzyme is called translation (protein synthesis). Protein synthesis occurs over ribosomes. The ribosomes are formed of two subunits. The rosette group formed by ribosomes is called polyribosome. In a polyribosome, ribosomes are held together by strand of /mRNA.
The steps involved in polypeptide synthesis are:
(1) Activation of amino acids : In the presence of ATP, an amino acid combines with its specific aminoacyl-fRNA synthetase.

(2) Charging of fRNA : The complex formed in the above step reacts with tRNA specific for the amino acid to form aminoacyl- tRNA complex.

(3) Initiation : The small subunit of ribosome (with the mRNA) attaches to the large subunit in such a way that the initiation codon (AUG) comes on the P-site of ribosome.

(4) Elongation : Amino acids carried by the tRNA are added one by one at A site of ribosome in the sequence of the codons and become joined together to form

(5) Termination : When the termination codon present on the /mRNA is reached, the polypeptide synthesis stops and the polypeptide is released.

Question 5.
Define an operon. Giving an example, explain an inducible operon.
Answer:
Operon is a functionally integrated genetic unit for the control of gene expression in bacteria, as proposed in the Jacob-Monod hypothesis. Typically, it comprises a closely linked group of structural genes, coding for protein, and adjacent loci controlling their expression-an operator site and a promoter site. Inducible operons are those which normally remain switched off but can be induced to function under certain conditions. Lac operon is an inducible operon. The ; gene of the lac operon codes for a repressor molecule that inhibits synthesis of the structural genes. Lac operon gets switched ‘on’ in the presence of lactose. The repressor molecule coded by i gene is inactivated by interaction with the inducer (lactose). This allows RN Apolymerase access to the promoter, and transcription proceeds. The operon gets switched ‘off’ in the absence of lactose. The repressor molecule binds again with the operator region of the operon and prevents RNA polymerase from transcribing the operon.

Question 6.
There is a paternity dispute for a child’. Which technique can solve the problem. Discuss the principle involved.
Answer:
The paternity dispute of a child can be solved by DNA fingerprinting.
The procedure in DNA-fingerprinting includes the following:

1. Extraction – DNA is extracted from the cells in a high-speed, refrigerated centrifuge.
2. Amplification – Many copies of the extracted DNA are made by polymerase chain reaction.
3. Restriction digestion – DNA is cut into fragments with restriction enzymes into precise reproducible sequences.
4. Separation of DNA sequences/restriction fragments – The cut DNA fragments are introduced and passed through electrophoresis containing agarose polymer gel, the separated fragments can be visualised by staining them with a dye that shows fluorescence under ultraviolet radiation.
5. Southern blotting – The separated DNA sequences are transferred on a nitrocellulose or nylon membrane.
6. Hybridisation – The nylon membrane is immersed in a bath and radioactive probes are added, these probes target a specific nucleotide sequences that is complementary to them.
7. Autoradiography – The nylon membrane is pressed on an X-ray film and dark bands develop at the probe sites.

After hybridisation with the radio labelled Variable Number of Tandem Repeats (VNTR) probe and autoradiography, bands of various sizes are formed. The bands form a characteristic pattern which varies from individual to individual. From the patterns developed by the samples A and B it can be confirmed to whether they belong to one individual or two different individuals. If the banding patterns are similar they belong to the same individual but if banding patterns As. are dissimilar then A and B are from different individuals.

Question 7.
Give an account of the methods used in sequencing the human genome.
Answer:
The methods involved two major approaches :
(1) One approach called as Expressed Sequence Tags (ESTs), focussed on identifying all the genes that are expressed as RNA.
(2) Second approach called as sequence annotation, was to simply sequence the whole set of genome, that included all the coding and non-coding sequences and later assigning functions to different regions in the sequences. The steps involved are as follows :

• The total DNA from the cell is isolated and converted into random fragments of relatively smaller sizes.
• These fragments are then cloned in suitable hosts using specialised vectors. The commonly used hosts are bacteria and yeast and the vectors are bacterial artificial chromosomes (BAC) and yeast artificial chromosomes (YAC).
• The fragments are then sequenced using automated DNA sequencers, which work on the principle developed by Frederick Sanger.
• The sequences were then arranged on the basis of certain overlapping regions present in them. This requires the generation of overlapping fragments for sequencing.
• Specialised computer based programmes were developed for alignment of the sequences.
• These sequences were annotated and assigned to the respective chromosomes.
• The next task was to assign the genetic and physical maps on the genome, this was generated using the information on polymorphism of restriction endonuclease recognition sites and certain repetitive DNA, sequences, called microsatellites.

Question 8.
List the various markers that are used in DNA fingerprinting.
Answer:
Various markers used in DNA fingerprinting are as follows:

1. Restriction fragment length polymor­phism (RFLPs)
2. Variable number of tendem repeats (VNTRs)
3. Short tendem repeats
4. Microsatellite DNA
5. Single nucleotide polymorphism (SNPs)

Question 9.
Replication was allowed to take place in the presence of radioactive deoxynucleotide precursors in coli that was a mutant for DNA ligase. Newly synthesised radioactive DNA was purified and strands were separated by denaturation. These were centrifuged using density gradient centrifugation. Which of the following would be a correct result?


Answer:
(a) Two peaks will be obtained, one of high molecular weight strands that are long, continuous strands which were synthesised on leading strand. The other peak is obtained of low molecular weight strands which is due to short Okazaki fragments synthesised on lagging strand because mutated DNA ligase will not join the Okazaki fragments.

We hope the NCERT Exemplar Solutions for Class 12 Biology chapter 6 Molecular Basis of Inheritance help you. If you have any query regarding .NCERT Exemplar Solutions for Class 12 Biology chapter 6 Molecular Basis of Inheritance, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 10 Social Science Economics Chapter 2 Sectors of Indian Economy

These Solutions are part of NCERT Solutions for Class 10 Social Science. Here we have given NCERT Solutions for Class 10 Social Science Economics Chapter 2 Sectors of Indian Economy.

TEXTBOOK EXERCISES

Question 1.
Fill in the blanks using the correct option given in the brackets :

1. Employment in the service sector__________ increased to the same extent as production. (has/has not)
2. Workers in the__________ sector do not produce goods. (tertiary/agricultural)
3. Most of the workers in the___________ sector enjoy job security. (organised/unorganised)
4. A_______ proportion of labourers in India are working in the unorganised sector.  (large/small)
5. Cotton is a__________ product and cloth is a____________ (natural/manufactured)
6. The activities in primary, secondary and tertiary sectors are______________ (independent/interdependent)

Answer:

1. has not
2. tertiary
3. organised
4. large
5. natural; manufactured
6. interdependent

Question 2.

1. How the sectors are classified on the basis of ownership of enterprises?
2. What is the secondary sector?
3.  What is GDP?
4. In terms of GDP what was the share of the tertiary sector in 2003?

Answer:

1. Public and Private sector.
2. Production of a commodity, mostly through the natural process is called the secondary sector.
3. GDP is the sum total of the value of all final goods and services of three sectors.
4. Between 50 percent to 60 percent.

Question 3.

1. How the problem of unirrigated land can be solved?
2. How the problem of low prices for crops can be solved? Give one solution.
3. How the debt burden of the farmers can be reduced?
4. How people/farmers can be provided a job in the offseason?
5. “The farmers are compelled to sell their grains to the local traders soon after harvest.” How this can be avoided?

Answer:

1. The problem of unirrigated land can be solved by the construction of canals by the government.
2. This problem can be solved by setting up cooperative marketing societies.
3. The debt burden of the farmers can be reduced by banks by granting credit at low interest.
4. The farmers can be given jobs in the offseason by setting up agro-based mills.
5. This can be avoided by the procurement of foodgrains by the government at a reasonable/ fixed price.

Question 4.
Classify the following workers under their correct sector :
Tourist guide, vegetable vendor, cobbler, Sahara Airlines
Answer:

1. Tourist guide – Organised sector
2. Vegetable vendor – Unorganised sector
3. Cobbler – Service sector
4. Sahara Airlines – Private sector

Question 5.
A research scholar looked at the working people in the city of Surat and found the following :

Place of work	Nature of employment	Percentage of working people
(1) In offices and factories registered with the government	Organised	15
(2) Own shops, office, clinics in marketplaces with formal license		15
(3) People working on the street, construction workers, domestic workers		20
(4) Working in small workshops usually not registered with the government

Complete the table. What is the percentage of workers in the unorganized sector in this
city (in percent) ?                                                                                            ,
Answer:
Complete table is given below :

Place of work	Nature of employment	Percentage of working people
(1) In offices and factories registered with the government	Organised	15
(2) Own shops, office, clinics in marketplaces with formal license	Organised	15
(3) People working on the street, construction workers, domestic workers	Unorganised	20
(4) Working in small workshops usually not registered with the government	Unorganised	50

Question 6.
Do you think the classification of economic activities into primary, second­ary, and tertiary sectors is useful? Explain how.
Answer:
The classification of economic activities into primary, tertiary and secondary is useful on account of the information it provides on how and where the people of a country are employed. also this helps in ascertaining as to which sector of economic activity contributes more or less to the country’s GDP and per capita income.

If the tertiary sector is developing much faster than the primary sector, then it implies that agriculture is depleting, and the government must take measures to rectify this. The knowledge that the agricultural profession is becoming unpopular or regressive can only come if we know which sector it belongs to. Hence it is necessary to classify economic activities into these there sectors for smooth economic administration and development.

Question 7.
For each of the sectors that we came across in this chapter, why should one focus on employment and GDP? Could there be other issues that should be examined? Discuss.
Answer:
For each of the sectors mentioned in this chapter, our focus should definitely be on employment and GDP. This is because growth in GDP and full employment are common goals of Five Year Plans and they also determine the size of a country’s economy. A focus on employment and GDP helps us to calculate and monitor the most important factors like per capita income, productivity, changes in employment rate, and contribution to GDP by the three sectors of the economy and thus, takes necessary steps required for the upliftment of the country’s economy as a whole.
Yes, the other issues which should be examined are

1. balanced regional development
2. equality in income and wealth among the people of the country.
3. how to eradicate poverty
4. modernization of technology
5. self-reliance of the country
6. how to achieve surplus food production in the country.

Question 8.
Make a long list of all kinds of work that you find adults around you doing for a living. In what way can you classify them? Explain your choice.
Answer:
(1) List of working adults: Engineer, doctor, washerman, electrician, shopkeeper, milk vendor, insurance manager, professor, government employee, a zamindar, vegetable seller, domestic help, a factory owner.

(2) Classification of the above kinds of work :

• Primary sector: Zamindar (landowner).
• Secondary sector: Factory owner.
• Tertiary sector: Engineer, doctor, washerman, electrician, shopkeeper, milk vendor, insurance manager, professor, government employee, vegetable vendor, and domestic help.
• Organised sector: Engineer, insurance manager, and doctor.
• Unorganised sector: Washerman, vegetable vendor, milk vendor, shopkeeper, electri­cian and domestic help.
• Public sector: Government employee and professor in a government college.
• Private sector: Engineer and doctor.

Question 9.
How is the tertiary sector different from other sectors? Illustrate with a few examples.
Answer:
The tertiary sector different from other two sectors. This is because other two sectors produce goods but, this sector does not produce goods by itself. But the activities under this sector help in the development of the primary and secondary sectors. These activities are an aid or support for the production process. For example, transport, communication, storage, banking, insurance, trade activities etc. For this reason this sector is also known as service sector.

Question 10.
What do you understand by disguised unemployment? Explain with an example each from the urban and rural areas.
Answer:
(1)

1. Disguised unemployment is a situation in which more people are engaged in an activity than the required ones,
2. This kind of Buder-employment is hidden in contrast to someone who does not have a job and is clearly visible as unemployed.
3. Hence it is also called disguised unemployment,
4. Under disguised unemployment even if the surplus people are removed from work, the production does not suffer.

(2) Rural areas: In rural area in India, more people are employed in agriculture than necessary. Even if you move a few people out, production will not be affected. As such workers in the agricultural sector are underemployed.

(3) Urban areas:

1. The disguised unemployment or under-employment exists in urban areas too. For example, there are thousands of casual workers in the service sector who search for daily employment,
2. They are employed as painters, plumbers and repairpersons and other doing odd jobs,
3. Many of them do not find work every day,
4. Similarly, there are other people of the service sector on the street pushing a cart or selling something who may spend the whole day but earn very little. They do this work because they do not have better opportunities.

Question 11.
Distinguish between open unemployment and disguised unemployment.
Answer:
The differences between open unemployment and disguised unemployment are as mentioned below :

Open Unemployment	Disguised Unemployment
(1) Open unemployment implies a situation when a person is unable to find any gainful work or job	Disguised unemployment is a situation in which more people are engaged in an activity than the required ones.
(2)   A person is able and willing to work but does not find gainful work. He does nothing	person gets work and are actually engaged in such an activity that he appears to be employed but he is not fully employed. He does not work upto his full capacity.
(3) In open unemployment a person loses his personal identity and sometimes suffers from mental illness. He may commit crimes and even make an attempt of suicide because it leads to depression.	In such cases there are surplus workers and if they are removed from work, production does not suffer. In this all remain busy in doing work although they do not work to their maximum strength.

Question 12.
“The tertiary sector is not playing any significant role in the development of Indian economy.” Do you agree? Give reasons in support of your answer.
Answer:
No, I do not agree with the statement that tertiary sector is not playing any significant role in the development of Indian economy. The reasons are as follows:

1. In terms of GDP this sector emerged as the largest producing sector in India surpassing the primary and secondary sectors. In 1973, the share of the tertiary sector in GDP was about 35% which increased to more than 50% in 2003. Over the thirty years between 1973 and 2003, while production in all three sectors increased, it has been the most in tertiary sector.

2. In terms of employment also the rate of growth of employment in tertiary sector between the same period was nearly 250%. This was negligible in primary sector.

Question 13.
Service sector in India employs two different kinds of people. Who are these ?
Answer:
Service sector in India employs two different kinds of people as mentioned below :

1. There are highly skilled and educated workers such as teachers and doctors.
2. On the other hand, a large number of workers are engaged in services such as small shopkeepers, repair persons etc. who barely manage to earn a living. They perform these services because they do not have any other work to do.

Question 14.
Workers are exploited in the unorganised sector. Do you agree with this view ? Give reasons in support of your answer.
Answer:
It is a fact that the workers are exploited in the unorganised sector due to the following reasons :

1. The unorganised sector consists of small and scattered units which are largely outside the control of the government.
2. There are rules and regulations but generally these are not followed by the employers.
3. Workers are employed on irregular basis. They are low paid and there is no provision
   for overtime, paid leave, holidays, leave due to sickness and other facilities e.g., provident fund.
4. Jobs are not secured. They can be asked to leave without any reason at the sweet will of the employer. Generally, when there is less work due to any reason, some workers are asked to leave.
5. Workers in this sector face social discrimination too because most of them belong to Scheduled Castes, Scheduled Tribes and Other Backward Classes.
6. Some workers who do repair work etc. are also exploited as they do not get regular work.
7. Farmers work on their own and hire labourers as and when they require.

Question 15.
How are the activities in the economy classified on the basis of employment conditions?
Answer:
Organised sector and unorganised sector.

Question 16.
Compare the employment conditions prevailing in the organised and unor­ganised sectors.
Answer:
The conditions in the organised and unorganised sectors are as follows :

Organised Sector	Unorganised Sector
(1) Organised sector covers those enterprises or places of work where the terms of employment are regular and therefore, people have assured work.	(1) Unorganised sector is characterised by small and scattered units where the terms of employment are not regular and people have no assured work
(2) They are registered by the government and have to follow its rules and regulations which are given in various laws such as Factories Act. Minimum Wages Act, Payment of Gratuity Act, Shops and Establishments Act etc.	(2) They are not registered by the government and do not follow any rules and regulations.
(3) It is called organised because it has some formal processes and procedures.	(3) It is called unorganised because it has no formal processes and procedures. All decisions are taken by the employers themselves.
(4) Some of these people may not be employed by any one but may work on their own but they too have to register (Tourist Guide) themselves with the government and follow rules and regulations.	(4) There is no need for registration. Employers are all in all. They take decisions in their own interest.
(5) They have fixed working hours. If they work more they get overtime. They get regular salary at the end of the month.	(5)There are no fixed working hours. The employees have to work according to their work and employers’ wish.
(6) Facilities such as PF, medical allowances are given to them.	(6) No facilities such as PF, medical allowance are generally given in this sector.
(7) They get paid holidays such as Sunday and other government holidays.	(7) They do not get paid holidays. However it is the sweet will of the employer to grant any holiday.
(8) Appointment letters with terms and conditions is issued to employees.	(8) Sometimes appointment letters are issued but these can be changed as and when desired by the employer.
(9)     Control of the government directly or indirectly.	(9) Generally, there is no control of the government. Rules are there but these are generally not followed by the employers.
(10)   In organised sector, a factory manager has to ensure facilities like drinking water and a safe working environment.	(10)  No arrangement such as of drinking water are made. Even if there is any such arrangement, that is rarely followed in practice.
(11) After retirement workers get pension ajid gratuity.	(11)  No pension and gratuity is granted in unorganised sector.

Question 17.
Explain the objective of implementing the NREGA 2005.
Answer:
The objective of implementing the NREGA 2005 was to provide 100 days of guaranteed employment to those people in rural India who can work, and are in need of work. This Right to Work has been implemented in 200 districts. If the government is unable to provide this employment, then it has to give unemployment allowances to the people.

Question 18.
Using examples from your area compere and contrast the activities and functions of private and public sectors?
Answer:
The activities and functions of private and public sectors in our area may be compared as mentioned below :

Private Sector	Public Sector
(1) The vegetable shops, grocery shops, sweet shops etc. are in private sector.	(1) Mother Dairy booths which sell vegetables, fruits, milk and milk products are in public sector.
(2) These are owned by private individuals.	(2) These are owned by public sector undertaking ‘Mother Dairy’
(3) Vegetables and other products are generally of good quality.	(3) The vegetables and fruits are generally of average or poor quality.
(4) The rates may be slightly higher	(4) The rates are lower than the market rates.
(5) The companies like Reliance, Tata, Airtel provide telephone and TV services which are of very good standard.	(5) MTNL provides telephone services. There are complaints against their services. On many occasions, telephones remain out of order, hut they do not charge for that period.
(6) The shopkeepers provide free home delivery service without any extra-charge.	(6) Mother Dairy or any other public under taking do not provide free home delivery service.
(7) Private schools provide education of good quality. Their students are well-dressed and disciplined. Their medium of in structions is always English.	(7) The schools run by MCD do not provide quality education. Their students are not well-dressed and disciplined. Their medium of instructions is generally Hindi.

Question 19.
Discuss and fill the following table giving one example each from your area :

	Well managed organisation	Badly managed organisation
Public sector
Private sector

Answer:

	Well managed organisation	Badly managed organisation
Public sector	MTNL	MCD
Private sector	Private Nursing Homes or Hospitals	TPDDL

 In the public sector, the services provided by MTNL are better than others and are cheap too. On the other hand, the services provided by the MCD such as sanitation are not satisfactory. Sometimes, the sewers are blocked during rainy season creating health problems in the area.

In the private sector, there are a few private nursing homes and hospitals which provide good medical facilities. But some of the companies such as TPDDL in the private sector have not risen up to the mark. There are still ‘breaks’ in the supply of electricity in the area which cause hardship to the people.

Question 20.
Give a few examples of public sector activities and explain why the govern­ment has taken them up.
Answer:
(1) A few examples of public sector activities are as mentioned below :

• Electricity – production and distribution.
• Selling of food grains – wheat and rice.
• Health and education.
• Safe drinking water.
• Housing facilities for the poor.
• To take care of the poorest and ignored regions.

(2) The government takes up the public sector activities due to the following reasons:

• The modern state is a welfare state which looks after the interests of the people. The government raises money through taxes and other ways and spends on public sector activities for the welfare of the people.
• Selling electricity at the cost of generation may push up the costs of production of industries. Small scale units may shutdown. Therefore government steps in by producing and supplying electricity at rates which these industries can afford. Govt, has to bear part of the cost.
• To have food security in the country, the government of India buys wheat and rice from farmers at a ‘fair price’. These are stored in its godowns and sold at a lower price to consumers through ration shops. The government bears some cost and in this way it supports both farmers and consumers.
• In modern welfare state, it is the responsibility of the government to provide health and education facilities for all citizens. Running proper schools and providing quality education is the duty of the government.
• In India half of children are malnourished. Hence government pays attention to aspects of human development such as availability of safe drinking water, housing facilities for the poor and food and nutrition.
• It is also the duty of the govt, to take care of the poorest and most ignored regions of the country through increased spending in such areas.

Question 21.
Explain, how public sector contributes to the economic development of a nation.
Answer:
Generally, economic development of a nation can be defined as long term increase in per capita income alongwith improvement in quality of life. The public sector contributes to the economic development of a nation in many ways as mentioned below :

• In public sector, the government owns most of the assets and provides services to the people. For example Railways and Post Offices. Railways is the biggest public undertaking. It is very useful for people, traders and industrialists. It is the most dependable mode of transport as it is least affected by weather conditions such as rain, fog compared to other modes of transport. It is better organised than any other form of transport. It is suitable for bulky and heavy goods.
  It is cheaper transport. It is the largest public undertaking. The railways provide greater employment opportunities for both skilled and unskilled labour. Over 16 lakh persons are depending upon railways for their livelihood. Thus it contributes a lot towards the economic development of the country.
• Public sector helps in development through Creation and infrastructure.
• It helps in the development of small, medium and cottage industries.
• It contributes to community development i.e., to the Human Development Index via health and educational facilities.
• It tries to ensure equality of income wealth and thus a balanced regional development.
• It ensures easy availability of goods at moderate rates.
  In India, the public sector has played a significant role in the eradication of illiteracy. The number of literates has increased from 9 per cent of females and 27 per cent of males in 1951 to 75 per cent of males and 54 per cent females in 2001. The government’s efforts in providing health facilities has raised average life expectancy from 32 years in 1950-51 to 61 years in 1993­Thus, we find that public sector contributes to the economic development of a nation in a significant way.

Question 22.
The workers in the unorganised sector need protection on the following issues : wages, safety and health. Explain with examples.
Answer:
(1) Wages: The workers in the unorganised sector do not get minimum wage fixed by the government. They are not paid any allowances like dearness allowance or city compensatory allowance. They are paid only their wages. They are not paid for the extra time, they work in the factory. They do not get any leave or paid holiday.

(2) Safety: No safety measures are taken in the factories for the protection of the workers. This results in injuries or death of labourers in the factory in case of fire or any other accident.

(3) Health: The workers in the unorganised sector are not provided any medical facilities. Whenever they fall ill or get injured, they get themselves treated by private doctors by paying for the treatment. Sometimes the working conditions are not hygienic. They are not paid any medical allowance too. Lack of medical facilities affect their health and efficiency badly.

Question 23.
A study in Ahmedabad found that out of 15,00,000 workers in the city, 11,00,000 worked in the unorganised sector. The total income of the city in this year (1997-98) was ? 60,000 million. Out of this ? 32,000 million was generated in the organised sector. Present this data as a table. What kind of ways should be thought of for generating more employment in the city ?
Answer:
(1) The data is given below as a table :

Sector	Year	Number of workers	Income
Organised	1997-98	4,00,000	32,000 million
Unorganised	1997-98	11,00,000	128,000 million
Total		15,00,000	60,000 million

(2) The following ways or steps should be taken by the government for generating more employment in the city :

1. Electricity should be provided to the factories regularly and at cheap rate especially to the small units. Government should bear part of the cost.
2. Adequate land should be given to people to’set up factories or small units.
3. Financial assistance should be given at less rate of interest.
4.  Raw materials should be made available to the factory owners and other small unit holders.
5. Transport and other facilities should be made’available.

Question 24.
The following table gives you the GDP in Rupees (crore) by the three sectors :

Year	Primary sector	Secondary sector	Tertiary sector
1950	80,000	19,000	39,000
2000	3,14,000	2,80,000	5,55,000

(1) Calculate the share of the three sectors in GDP for 1950 and 2000.
(2) Show the data as a bar diagram similar to Graph 2 in the chapter.
(3) What conclusions can we draw from the bar graph
Answer:
(1) The share of the three sectors in GDP for 1950 and 2000 was as given below :

	1950	2000
(a) Primary sector	57.97%	27.32%
(b) Secondary sector	13.77%	24.36%
(c) Tertiary sector	28.26%	24.36%

(2) Share of sectors in GDP is shown in the bar diagram given below :

(3) From the bar diagram the following conclusions can be drawn :

In 1950, the share of primary sector in GDP was more than other sectors. It was 57.97% in comparison to 13.77% and 28.26% of secondary and tertiary sectors respectively.
However in 2000, the share of primary sector decreased from 57.97% to 27.32% while the share of tertiary sector increased from 28.26% to 48.32%. The share of secondary sector too increased from 13.77% in 1950 to 24.36% in 2000

We hope the NCERT Solutions for Class 10 Social Science Economics Chapter 2 Sectors of Indian Economy help you. If you have any query regarding NCERT Solutions for Class 10 Social Science Economics Chapter 2 Sectors of Indian Economy, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 10 Social Science Economics Chapter 3 Money and Credit

These Solutions are part of NCERT Solutions for Class 10 Social Science. Here we have given NCERT Solutions for Class 10 Social Science Economics Chapter 3 Money and Credit.

TEXTBOOK EXERCISES

Question 1.
In situations with high risks, credit might create further problems for the borrower. Explain
Answer:
Whether a credit would be useful or not, will depend on a number of factors like – risks involved, whether there is some support against a loss, terms of credit, etc. It is a fact that in situations with high risks, credit might create further problems for the borrower. For example, credit taken by farmers for cultivation might create problems for the farmer at some times. Crop production involves high costs on inputs such as HYV seeds, fertilizers, pesticides, irrigation etc.

Farmers generally take loans at the beginning of the season and repay the loan after harvest. But the failure of the crop makes loan repayment impossible. Then in order to repay the loan sometimes, they become bound to sell part of their land. So, their situations become worse than before. The incidences of farmers’ suicides especially in Maharashtra are the burning examples of this situation. Thus, whether credit would be useful or not, depends on the various risks involved in the situation.

Question 2.
How does money solve the problem of double coincidence of wants ? Explain with an example of your
own. [CBSE 2016]
Answer:

1. Money solves the problem of double coincidence of wants because it acts as an intermediate in the exchange process.
2. People may purchase anything with money.
3. There is no need to have any goods or commodities for exchange.
4. Money acts as a medium of exchange.

For example, a person working as an engineer in a government department gets salary from his office. With that money (salary) he purchases different goods from the market according to the requirements of his family. He makes payment in cash and does not need any product for exchange as required under the double coincidence of wants. Thus, money acts as an intermediate in the exchange process.

Question 3.
How do banks mediate between those who have surplus money and those who need money?
Or
What does the Bank do with the deposits which they accept from the public ?
Answer:
We know that banks accept deposits from the people who have surplus money and also pay interest on the deposits.
But banks keep only a small portion (15 percent in India) of their deposits as cash with themselves. This is kept as a provision to pay the depositors who might come to withdraw money from their accounts in the bank on any day. They use the major portion of the deposits to extend loans to those who need money. In this way, banks mediate between those who have surplus money and those who need money.

Question 4.
Look at a 10 rupee note. What is written on top ? Can you explain this statement ?
Answer:
The following words are written at the top of a 10 rupee note :
“Reserve Bank of India Guaranteed By The Central Government”
“I promise to pay the bearer the sum of Ten Rupees.” Governor.

1. It implies that the notes are issued by the Reserve Bank of India.
2. The Governor of the Reserve Bank promises to pay tjie bearer the sum of ten rupees.
3. The notes have been guaranteed by the Central Government and in case of failure of the currency e. Ten Rupee notes, people can claim tile amount from the Central Government.
4. It also implies that the use of rupee is a legal currency and no one can refuse payment made in it.
5. It is medium of exchange in India.

Question 5.
Why do we need to expand formal sources of credit in India ?
Answer:
We need to expand formal sources of credit in India for many reasons:

1. Compared to formal lenders, most of the informal lenders charge much higher interest rates on loans like 3% to 5% per month i.e. 36% a year.
2. Besides the high-interest rate, informal lenders impose various other tough conditions. For example, they make the farmers promise to sell the crop to him at a low price. There is no such condition in the formal sector.
3. Informal lenders do not treat well with the borrowers. On the other hand, there is no such situation in the formal sector.
4. The Reserve Bank of India supervises the functioning of formal sources of loans. In contrast, there no organization which supervises the credit activities of lenders in the informal sector.
5. Loans taken by poor people from informal lenders sometimes, lead them to debt-trap because of high-interest rates.
6. The formal sources of credit in India still meets only about half of the total credit needs of rural people.

So, it is necessary that the formal sources of credit expand their lending, especially in rural areas so that the dependence on informal sources of credit reduces as this will also help in the development of the country.

Question 6.
What is the basic idea behind the SHGs for the poor? Explain in your own words.
Answer:

1. The basic idea behind the SHGs (Self-Help Groups) is to organise rural poor, in particular women, so that they may pool their savings and help them to borrow money without collateral.
2. The banks are not present in every village. Even if there is a bank in rural area, getting a loan from a bank is much more difficult that taking a loan from informal sources because the bank loans require proper documents and collateral.
3. So to solye the problems of cheaper loans without collateral in rural areas SHGs have been formed.

Question 7.
What are the reasons why the banks might not be willing to lend to certain borrowers ?
Answer:
Bank loans require proper documents and collateral. People who do not apply for loan with proper documents and collateral are refused loans by the banks. Generally, the poor fall in this category and absence of collateral is one of the main reasons for not sanctioning loans to them.

Question 8.
In what ways, does the Reserve Bank of India supervise the functioning of banks ? Why is this
necessary ?                                                                            ,
Answer:
(1) The Reserve Bank of India supervises the functioning of banks in the following ways :

• The RBI monitors that the banks actually maintain the required cash balance.
• It sees that the banks give loans not-just to profit-making businesses and traders but also to small cultivators, small-scale industries, small-borrowers.
• The banks submit information to the RBI about loans sanctioned to different categories of persons along with terms and conditions of the loans. In this way, RBI sees that the loans are sanctioned to all including the poor.

(2) The supervision of the Reserve Bank of India over the functioning of the banks is necessary. It is to know how much the banks are lending, to whom and at what interest rate. It is to ensure that the banks do not exploit the borrowers like the moneylenders in the rural areas.

Question 9.
Analyse the role of credit for development.
Answer:
Credit plays a crucial role in a country’s development. By sanctioning loans to developing industries and trade, banks provide them with the necessary aid for improvement. This leads to increased production, employment, and profits. However, caution must be exercised in the case of high risks so that losses do not occur.

This advantage of loans also needs to be manipulated and kept under an administrative hold because loans from the informal sector include high-interest rates that may be more harmful than good. For this reason, it is important that the formal sector gives out more loans so that borrowers are not duped by moneylenders, and can ultimately contribute to national development.

Question 10.
Manav needs a loan to set up a small business. On what basis will Manav decide whether to borrow from the bank or the moneylender? Discuss.
Answer:
Manav will decide to borrow from the bank or the moneylender on the following basis :

1. Rate of interest.
2. Terms for repayment of loan,
3. Other conditions such as collateral.
4. Wherever the above conditions favour him or are more satisfactory, he will take loan from
   them accordingly. Generally, in India, the terms and conditions that are offered in the formal sector i.e., the banks and cooperatives are better than the informal sector i.e., moneylenders who charge much higher rate of interest.

Question 11.
In India, about 80 per cent of farmers are small farmers, who need credit for cultivation.
(a) Why might banks be unwilling to lend to small farmers ?
(b) What are the other sources from which the small farmers can borrow ?
(c) Explain with an example how the terms of credit can be unfavourable for the small farmer.
(d) Suggest some ways by which small farmers can get cheap credit.
Answer:
(a) Banks might not be willing to lend to small farmers because they don’t have collateral security to deposit in the bank. Some of these farmers are not in the position of paying the loan, due to already existing loans.

(b) The other sources of borrowing are from moneylenders, employer, self-help group, landlord, etc.

(c) For example, if a person takes a loan from his/her landlord on the basis of security of his/her land. At the end, be/she is not able to pay the loan then the landlord can sell the land and get his money back.

(d) Small farmers can get cheap credit with the help of a self-help group (SHGs) from the bank and they can repay the loan easily after 3 or 4 years. The rate of interest is also low as compared to other sources of credit.

Question 12.
Fill in the blanks :

1. Majority of the credit needs of the_____________ households are met from informal sources.
2. ___________ costs of borrowing increase the debt-burden.
3. __________ issues currency notes on behalf of the Central Government.
4. Banks charge a higher interest rate on loans than what they offer on ___________
5. _______ is an asset that the borrower owns and uses as a guarantee until the loan is repaid to the lender.

Answer:

1. poor
2. High
3. Reserve Bank of India
4. deposits
5. Land

Question 13.
Choose the most appropriate answer :
(1) In an SHG most of the decisions regarding savings and loan activities are taken by
(a) Bank
(b) Members
(c) Non-government organization
(d) Formal sources of credit does not include
Answer:
(1) (b) Members

We hope the NCERT Solutions for Class 10 Social Science Economics Chapter 3 Money and Credit help you. If you have any query regarding NCERT Solutions for Class 10 Social Science Economics Chapter 3 Money and Credit, drop a comment below and we will get back to you at the earliest.

NCERT Exemplar Solutions for Class 12 Biology chapter 3 Human Reproduction

These Solutions are part of NCERT Exemplar Solutions for Class 12 Biology. Here we have given NCERT Exemplar Solutions for Class 12 Biology chapter 3 Human Reproduction

Multiple Choice Questions

Question 1.
Choose the incorrect statement from the following. 
(a) In birds and mammals internal fertilisation takes place.
(b) Colostrum contains antibodies and nutrients.
(c) Polyspermy in mammals is prevented by the chemical changes in the egg surface.
(d) In the human female implantation occurs almost seven days after fertilisation.
Answer:
(c) : Polyspermy is the entry of several sperms into the egg during fertilisation. It occurs in animals with yolky eggs (e.g., birds). In humans, although only one sperm nucleus actually fuses with the egg nucleus. Due to acrosomal reaction, plasma membrane of the sperm fuses with the plasma membrane of the secondary oocyte, so that the sperm contents enter the oocyte. Binding of the sperm to the secondary oocyte induces depolarisation of the oocyte plasma membrane. Depolarisation  prevents polyspermy.

Question 2.
Identify the correct statement from the following.
(a) High levels of estrogen triggers the ovulatory surge.
(b) Oogonial cells start to proliferate and give rise to functional ova in regular cycles from puberty onwards.
(c) Sperms released from seminiferous tubules are highly motile.
(d) Progesterone level is high during the post ovulatory phase of menstrual cycle.
Answer:
(d)

Question 3.
Spot the odd one out from the following structures with reference to the male reproductive system.
(a) Rete testis
(b) Epididymis
(c) Vasa efferentia
(d) Isthmus
Answer:
(d) : Females have two oviducts (or Fallopian tubes). Each oviduct has three regions, infundibulum, ampulla and isthmus. Isthmus is the narrow part closest to uterus, while infundibulum is the first part of oviduct that is encountered by released ova.

Question 4.
Seminal plasma, the fluid part of semen, is contributed by
(1) seminal vesicle
(2) prostate
(3) urethra
(4) bulbourethral gland
(a) (i) and (ii)
(b) (i), (ii) and (iv)
(c) (ii), (iii) and (iv)
(d) (i) and (iv)
Answer:
(b) : Seminal plasma is the fluid part of semen and is contributed by seminal vesicles, prostate gland and bulbourethral glands. Seminal vesicles contribute fructose, citric acid and other nutrients as well as fibrinogen and prostaglandins. Secretions from prostate gland contain calcium ions, phosphate ion etc. and are alkaline in nature. Bulbourethral glands secrete alkaline mucus which is important for the lubrication of penis.

Question 5.
Spermiation is the process of the release of sperms from
(a) seminiferous tubules
(b) vas deferens
(c) epididymis
(d) prostate gland.
Answer:
(a) : Spermiation is the release of sperm from seminiferous tubules. From here, they will be transported to vasa efferentia and then to epididymis where maturation of sperm occurs.

Question 6.
Mature Graafian follicle is generally present in the ovary of a healthy human female around
(a) 5-8 day of menstrual cycle
(b) 11-17 day of menstrual cycle
(c) 18-23 day of menstrual cycle
(d) 24-28 day of menstrual cycle.
Answer:
(b) : Starting from puberty, monthly changes in ovaries and uterus also starts. The layer of cells surrounding primary oocyte are called granulosa cells and together, they are  called primary follicle. The growth of the follicles is under the influence of pituitary hormones FSH and LH. Further growth is also stimulated by estrogen. The mature Graafian follicle is present in the ovary around 11-17 day of menstrual cycle and on rupture of which, ovum is released (because of LH surge, 1-2 days before ovulation).

Question 7.
Acrosomal reaction of the sperm occurs due to
(a) its contact with zona pellucida of the ova
(b) reactions within the uterine environment of the female
(c) reactions within the epididymal environ­ment of the male
(d) androgens produced in the uterus.
Answer:
(a) : When head of sperm binds to zona pellucida (ZP) of ovum the acrosome release its contents by exocytosis. The content inside acrosome includes various hydrolytic enzymes like hyaluronidase, corona penetrating enzymes etc. This is called acrosomal reaction. It helps the sperm to reach the plasma membrane of ovum, by dissolving corona radiata and zona pellucida.

Question 8.
Which one of the following is not a male accessory gland?
(a) Seminal vesicle
(b) Ampulla
(c) Prostate
(d) Bulbourethral gland
Answer:
(b) : Ampulla is the part of oviduct between the infundibulum and isthmus. It  is at tfre ampullary-isthmus junction, where fertilisation take place.

Question 9.
The immature male germ cell undergoes division to produce sperms by the process of spermatogenesis. Choose the correct one with reference to above.
(a) Spermatogonia have 46 chromosomes and always undergo meiotic cell division.
(b) Primary spermatocytes divide by mitotic cell division.
(c) Secondary spermatocytes have 23 chromo­somes and undergo second meiotic division.
(d) Spermatozoa are transformed into spermatids.
Answer:
(c) : Spermatogonia are diploid cells on the inside wall of seminiferous tubules that multiply by mitotic divisions. Some of the spermatogonia called primary spermatocyte undergo meiosis-I to give rise to secondary spermatocytes (haploid). Each secondary spermatocyte undergoes meiosis-II to give rise to two haploid spermatids which are transformed to spermatozoa by spermiogenesis.

Question 10.
Match between the following representing parts of the. sperm and their functions and choose the correct option.

(a) A-{ii), B-(iv), C-(i), D-(iii)
(b) A-(iv), B-(iii), C-(i), D-(ii)
(c) A-(iv), B-(i), C-(ii), D-(iii)
(d) A-(ii), B-(i), C-(iii), D-(iv)
Answer:
(b)

Question 11.
Which among the following has 23 chromo­somes?
(a) Spermatogonia
(b) Zygote
(c) Secondary oocyte .
(d) Oogonia
Answer:
(c) : Spermatogonia are the cells on the inside wall of seminiferous tubules and consist of 46 chromosomes. Oogonia are also diploid cells and formed in the foetal ovary. Zygote is also diploid and fertilised ovum formed by fusion of male and female gametes. Secondary oocyte has 23 chromosomes and is formed by meiosis-I of primary oocyte.

Question 12.
Match the following and choose the correct option.

(a) A-(ii), B-(i), C-(iii), D-(iv)
(b) A-(iii), B-(iv), C-(ii), D-(i)
(c) A-(iii), B-(i), C-(ii), D-(iv)
(d) A-(ii), B-(iv), C-(iii), D-(i)
Answer:
(b)

Question 13.
Which of the following hormones is not secreted by human placenta?
(a) hCG
(b) Estrogens
(c) Progesterone
(d) LH
Answer:
(d) : LH is the hormone that is not secreted by human placenta. It is secreted by anteribr pituitary. Initially during pregnancy, hCG performs the function of LH of maintaining corpus luteum for the secretion of progesterone. Later (around 16^th week) in pregnancy, when placenta itself starts secreting estrogen and progesterone, corpus luteum regresses.

Question 14.
The vas deferens receives duct from the seminal vesicle and opens into urethra as
(a) epididymis
(b) ejaculatory duct
(c) efferent ductule
(d) Ureter
Answer:
(b)

Question 15.
Urethral meatus refers to the
(a) urinogenital duct
(b) opening of vas deferens into urethra
(c) external opening of the urinogenital duct
(d) muscles surrounding the urinogenial duct.
Answer:
(c) : Urethral meatus refers to the external opening of urinogenital duct, through which in males, urine and semen both exits the body.

Question 16.
Morula is a developmental stage
(a) between the zygote and blastocyst
(b) between the blastocyst and gastrula
(c) after the implantation
(d)between implantation and parturition.
Answer:
(a) : After fertilisation, zygote is formed. Zygote undergoes, mitotic divisions, called cleavage, to form 2, 4, 8 and 16 daughter cells called blastomeres. These divisions start when zygote is moving towards uterus. It is called morula at 8-16 cell stage and it continues to divide to form blastocyst. Blastocyst has two type of cells : trophoblast cells and inner cell mass. Around 7 day after fertilisation, implantation through trophoblast cells occurs.

Question 17.
The membranous cover of the ovum at ovulation is
(a) corona radiata
(b) zona radiata
(c) zona pellucida
(d) Chorion
Answer:
(a) : The outermost membranous cover of the ovum at ovulation is corona radiata. It is formed by follicular cells. Inner to corona radiata is zona pel lucid a, which is made up of three different glycoproteins secreted by the ovum itself.

Question 18.
Identify the odd one from the following.
(a) Labia minora
(b) Fimbriae
(c) Infundibulum
(d) Isthmus
Answer:
(a) : Labia minora are paired folds of tissues under labia majora which in turn surrounds the vaginal opening. Fimbriae, infundibulum and isthmus, along with ampulla are parts of oviduct (or Fallopian tube).

Very Short Answer Type Questions

Question 1.
Given below are the events in human reproduction. Write them in correct sequential order. Insemination, gametogenesis, fertilisation, parturition, gestation, implantation
Answer:
Gametogenesis, insemination, fertilisa­tion, implantation, gestation, parturition.

Question 2.
The path of sperm transport is given below. Provide the missing steps in blank boxes.

Answer:
Seminiferous tubules —>Rete testis —> Vasa efferentia —> Epididymis —> Vas deferens -> Urethra

Question 3.
What is the role of cervix in the human female reproductive system?
Answer:
Role of cervix in human female reproductive system:

1. Cervical canal e., the cavity of cervix and vagina together form birth canal to facilitate parturition.
2. It regulates the passage of sperms into the uterus.

Question 4.
Why are menstrual cycles absent during pregnancy?
Answer:
Levels of progesterone and estrogen are high during pregnancy. Their high levels suppress the release of gonadotropin (FSH) responsible for transformation of primary follicles into Graafian follicles, and for ovulation. And, no ovulation means, no menstrual cycle.

Question 5.
Female reproductive organs and associated functions are given below in column A and B. Fill the blank boxes.

Answer:
a – Fertilisation, b – Uterus

Question 6.
From where the parturition signals arise- mother or foetus? Mention the main hormone involved in parturition.
Answer:
Parturition is induced by complex neuroendocrine mechanism. Signals for parturition originate from fully developed foetus and placenta which induce mild uterine contractions called foetal ejection reflex. Oxytocin from maternal pituitary induces strong uterine contractions of myometrium, which leads to expulsion of baby (parturition) through birth canal.

Question 7.
What is the significance of epididymis in male fertility?
Answer:
Epididymis helps in storage, nutrition and physiological maturation of sperms. It also aids motility to sperms.

Question 8.
Give the names and functions of the hormones involved in the process of spermatogenesis. Write the names of the endocrine glands from where they are released.
Answer:
The name of hormones, its endocrine glands and functions of the hormones involved in the process of spermatogenesis are given in the following table:

Hormone	Endocrine gland	Function
GnRH (Gonado­ tropin releasing hormone)	Released from hypothalamus	Stimulates the anterior pituitary to release FSH and LH.
Follicle stimulating hormone (FSH)	Released from anterior pituitary	Stimulates Sertoli cells to secrete certain factors which help in spermatogenesis.
Luteinising hormone (LH)	Released from anterior pituitary	Stimulates Leydig’s cells of testes to secrete androgens (testosterone) which regulate

Question 9.
The mother germ cells are transformed into a mature follicle through series of steps. Provide the missing steps in the blank boxes.

Answer:

Question 10.
During reproduction, the chromosome number (2n) reduces to half (n) in the gametes and again the original number (2n) is restored in the offspring. What are the processes through which these events take place?
Answer:
Chromosome number is reduced to half (n) during the process of gametogenesis, and it is again restored to (2n) as a result of fertilisation.

Question 11.
What is the difference between a primary oocyte and a secondary oocyte?
Answer:
Primary oocyte is a diploid structure surrounded by single layer of follicular  through mitosis and differentiation. Secondary oocyte is a hapoid structure and is surrounded by a few layer of granular cells and theca. It is formed from primary oocyte after it undergoes first meiotic division.

Question 12.
What is the significance of ampullary-isthmic junction in the female reproductive tract?
Answer:
Ampullary-isthmic junction of oviduct is a site for fertilisation.

Question 13.
How does zona pellucida of ovum help in preventing polyspermy?
Answer:
During fertilisation, a sperm comes in contact with zona pellucida layer of ovum and induces changes in the membrane known as cortical reaction. This blocks the entry of additional sperms (polyspermy) and maintains monospermy.

Question 14.
Mention the importance of LH surge during menstrual cycle.
Answer:
Rapid secretion of LH leading to its maximum level during mid cycle is known as LH surge. It induces rupture of Graafian follicle and release of ovum (ovulation).

Question 15.
Which type of cell division forms spermatids from the secondary spermatocytes?
Answer:
Secondary spermatocytes undergo meiosis II to form spermatids. Secondary spermatocytes and spermatid both are haploid and this meiosis II is known as equational division.

Short Answer Type Questions

Question 1.
A human female experiences two major changes, menarche and menopause during her life. Mention the significance of both the events.
Answer:
The first menstrual cycle in females is known as menarche. It indicates the attainment of sexual maturity and puberty stage in females. It signifies the maturation and readiness of the female reproductive system for child bearing. It occurs usually at the age of 10-14 years.Menopause is the period of end of cyclic change in females. It indicates the end of reproductive cycle or fertile period in females. It occurs between 45-55 years of age.

Question 2.
(a) How many spermatozoa are formed from one secondary spermatocyte?
(b) Where does the first cleavage division of zygote take place?
Answer:
(a) A secondary spermatocyte gives rise to two spermatids, which get  transformed into two spermatozoa.
(b) First cleavage division of zygote takes place in Fallopian tubes of females.

Question 3.
Corpus luteum in pregnancy has a long life. However, if fertilisation does not take place, it remains active only for 10-12 days. Explain.
Answer:
Zygote formed after fertilisation gets implanted in the inner lining of uterus, called endometrium. Neural signals are conducted to hypothalamus to sustain LH secretion. This helps in maintaining corpus luteum and continue the secretion of progesterone during gestation period. But when fertilisation does not take place, neural signals are not sent to hypothalamus. As a result corpus luteum starts degenerating and can stay alive only for 10-12 days.

Question 4.
What is foetal ejection reflex? Explain how it leads to parturition?
Answer:
Foetal ejection reflex are the uterine contractions induced by fully developed foetus and placenta which signals for parturi­tion.
This stimulates the posterior pituitary of the mother to release oxytocin. Oxytocin causes stronger uterine contractions of smooth muscles of myometrium called labour pains, which further stimulate more secretion of oxytocin. The stimulatory reflex  continues resulting in stronger and stronger contractions and leading to expulsion of the baby (parturition) through birth canal.

Question 5.
Except endocrine function, what are the other functions of placenta?
Answer:
Functions of placenta other than endocrine functions are:

1. Nutritive organ – Food materials pass from the mother’s blood into the foetal blood through the placenta.
2. Digestive organ – The trophoblast of the placenta digests (breaks down) proteins before passing them into the foetal blood.
3. Respiratory organ – Oxygen diffuses from the maternal blood into the foetal blood through the placenta. Carbon dioxide diffuses from the foetal blood into the maternal blood also through the placenta for elimination by the mother’s lungs. Foetal haemoglobin has a greater affinity for oxygen than adult haemoglobin.
4. Excretory organ – Nitrogenous wastes, such as urea, pass from the foetal blood into the maternal blood via placenta for elimination by mother’s kidneys.
5. Storage organ – The placenta stores glycogen for the foetus before liver is formed.
6. Barrier – Placenta serves as an efficient barrier and allows those materials to pass into the foetal blood that are necessary.

Question 6.
Why doctors recommend breast feeding during initial period of infant growth?
Answer:
Human milk consists of water, minerals, fats, proteins and sugar necessary for development of the child. The milk produced’ during initial days of lactation is called colostrum. It is rich in proteins (lactalbumin and lactoprotein) and various other nutrients. It also contains certain antibodies (IgA), which provide passive immunity to the baby.

Question 7.
What are the events that take place in the ovary and uterus during follicular phase of the menstrual cycle.
Answer:
(1) Changes inside the ovary during follicular phase :-

• Primary follicle gets transformed into Graafian follicle.
• Increase in level of estrogen

(2) Changes in uterus during follicular phase :-

• Proliferation of endometrium.
• Endometrium becomes highly vascular and glandular.

Question 8.
Given is a flow chart showing ovarian changes during menstrual cycle. Fill in the spaces giving the name of the hormones responsible for events shown.

Answer:
a – FSH and LH
b – LH
c – Progesterone

Question 9.
Give a schematic labelled diagram to represent oogenesis (without descriptions).
Answer:

Question 10.
What are the changes in the oogonia during the transition of a primary follicle to Graafian follicle?
Answer:
Oogonia divide by mitosis forming primary oocyte which then gets surrounded by a layer of granulosa cells to form primary follicle. The primary follicles are surrounded by more layers of granulosa cells called secondary follicles.The secondary follicle soon changes into a tertiary follicle which is characterised by a fluid filled cavity called follicular antrum. The tertiary follicle is further converted into mature follicle or Graafian follicle. The formation of Graafian follicle through various stages is called folliculogenesis.

Long Answer Type Questions

Question 1.
What role does pituitary gonadotropins play during follicular and ovulatory phases of menstrual cycle? Explain the shifts in steroidal secretions.
Answer:
The menstrual cycle consists of four phases: menstrual phase, follicular phase (proliferative phase), ovulatory phase and secretory phase. Hormonal control during follicular phase:

• FSH from pituitary transforms the primary follicle into Graafian follicle.
• FSH also stimulates Graafian follicular cells to secrete estrogen.
• Estrogen causes proliferation of endo­metrium of the uterine wall.

Hormonal control during ovulatory phase :

• Pituitary glands are stimulated by estrogen to release LH.
• LH surge (maximum level of LH) causes ovulation from the ovary on 14^th day of menstruation cycle. LH also induces transformation of Graafian follicle into corpus luteum, inside the ovary. LH stimulates corpus luteum to secrete progesterone to help implantation,placentation, and maintenance of pregnancy.
• In menstrual phase, there is reduction of progesterone and estrogen. Gonado­tropin releasing hormone (GnRH) stimulates the release of FSH and LH. FSH stimulates the ovarian follicles to produce estrogens during proliferative phase. LH stimulates the ovulation in ovulatory phase.
• LH develops corpus luteum which causes increased production of progesterone in secretory phase.

Question 2.
Meiotic division during oogenesis is different from that in spermatogenesis. Explain how and why?
Answer:
Primary spermatocyte divides by meiosis I to form two secondary spermato­cytes. Primary oocyte undergoes meiosis I to form one secondary oocyte and one polar body.
Secondary spermatocyte divides by meiosis II to produce two spermatids. Secondary oocyte divides by meiosis II to form one ovum and one polar body.
A spermatocyte forms four spermatozoa. An oocyte forms only one egg or ovum. Unequal cell divisions during oogenesis, makes the ovum much larger than the other three polar bodies. Ovum has more cytoplasm and more organelles, it has a better chances of surviving. The male makes million of tiny sperms while, the female makes one egg per month because the sperms have to search for the eggs and only a few succeed in this task.

Question 3.
The zygote passes through several developmental stages till implantation. Describe each stage briefly with suitable diagrams.
Answer:

1. The zygote moves from isthmus to uterus and undergo mitotic divisions called cleavage divisions.
2. It forms 2, 4, 6, 8,16 daughter cells, called  blastomeres.
3. The embryo with 8-16 blastomeres is called morula.
4. The morula continues to get transformed into blastocyst.
5. The blastomeres in the blastocyst are arranged into an outer layer called trophoblast, and an inner group of cells attached to trophoblast called inner cell mass.
6. The trophoblast layer gets attached to the endometrium and inner cell mass gets differentiated as the embryo.
7. After attachment uterine cells divide rapidly and cover the blastocyst.
8. As a result the blastocyst becomes embedded in the endometrium of the uterus.
9. This is known as implantation, and it leads to pregnancy.
   

Question 4.
Draw a neat diagram of thefemale reproductive system and label the parts associated with the following (a) production of gamete, (b) site of fertilisation(c) site of implantation and, (d) birth canal.
Answer:

Question 5.
With a suitable diagram, describe the organisation of mammary gland.
Answer:
Mammary glands are paired structures consisting of glandular tissue, the fibrous tissue and variable amount of fat. They are compound tubulo-alveolar modified sweat glands. The glandular tissue of breast consists of about 15-20 lobes of milk glands. Each lobe is formed of many lobules containing cluster of cells called alveoli. The cells of alveoli secrete milk, which is stored in the lumen (cavities) of alveoli. The alveoli open into mammary  tubules, the tubules of each lobe join to form a mammary duct. Several mammary ducts join to form a wider mammary ampulla, which is connected to lactiferous duct, through which milk is sucked out. Mammary glands are functional in females and vestigial in males. Breasts in females are small sized upto puberty. The size increases after puberty under stimulation of estrogen. It further increases during pregnancy and after child birth under the stimulation of prolactin and progesterone.

We hope the NCERT Exemplar Solutions for Class 12 Biology chapter 3 Human Reproduction help you. If you have any query regarding NCERT Exemplar Solutions for Class 12 Biology chapter 3 Human Reproduction, drop a comment below and we will get back to you at the earliest.