Here we are providing Class 12 Biology Important Extra Questions and Answers Chapter 9 Strategies for Enhancement in Food Production. Important Questions for Class 12 Biology are the best resource for students which helps in Class 12 board exams.

Class 12 Biology Chapter 9 Important Extra Questions Strategies for Enhancement in Food Production

Strategies for Enhancement in Food Production Important Extra Questions Very Short Answer Type

Question 1.
Define the livestock.
Answer:
Domesticated animals reared to provide milk, hide, flesh, etc.

Question 2.
What do you mean by the white revolution?
Answer:
Increased production of milk.

Question 3.
Who is called the Father of the White revolution?
Answer:
Dr. V. Kurien.

Question 4.
Give one example of each of the indigenous and exotic milch breeds of cow.
Answer:
Indigenous breed: Sahiwal; Exotic breed: Brown swiss.

Question 5.
Name one bacterial and one viral disease of cattle.
Answer:
Bacterial disease: Anthrax ;
Viral disease: foot and mouth disease.

Question 6.
What are the main advantages of cross-breeds of fowls over indigenous breeds?
Answer:
These consume less feed and produce more eggs.

Question 7.
Name two high-yielding cross-breeds of fowls.
Answer:
“B-77” and “HH-260”.

Question 8.
What is meant by ‘hidden hunger’?
Answer:
It is the consumption of food that is deficient in some essential nutrients like micronutrients, proteins, and vitamins.

Question 9.
Why are plants obtained by protoplast culture called somatic hybrids?
Answer:
Plants obtained from protoplast culture are called somatic hybrids because they are formed from hybrid cells developed through the fusion of genetically different somatic cells.

Question 10.
A person who is allergic to pulses was advised to take a capsule of Spirulina daily. Give the reasons for the advice.
Answer:
Spirulina is rich in proteins. Thus it overcomes the protein deficiency due to non-eating of pulses.

Question 11.
Give examples of some microorganisms working for SCP.
Answer:
Spirulina maxima, Methylophilus methylotrophs, Candida utilize, Paecilomyces variety.

Question 12.
What is the importance of male sterility in plant breeding?
Answer:
Plant breeders use male-sterile plants in artificial hybridization to avoid self-pollination.

Question 13.
Give the significance of superovulation.
Answer:
It increases the production of eggs (6-8) per cycle. Thus it helps in increasing herd size in a short time.

Question 14.
What is the economic value of Spirulina? (CBSE 2008, 2009)
Answer:
Spirulina can be grown on easily available cheap materials like wastewater from potato processing plants, molasses, and even sewage. They provide a large quantity of protein-rich food. Hence it also minimizes pollution.

Question 15.
List the products obtained from bee-keeping. (CBSE Delhi 2008)
Answer:
Honey, wax, royal jelly, and bee venom.

Question 16.
What is the importance of MOET? (CBSE Delhi 2013)
Answer:
MOET is multiple ovulation embryo transfer technologies.

Importance:

  1. It is used to increase herd size in short term.
  2. It is also meant for the successful production of hybrids.

Question 17.
Name any two diseases the ‘Himgiri’ variety of wheat is resistant to. (CBSE Outside Delhi 2013)
Answer:

  1. Leaf and stripe rust
  2. Hill bunt.

Question 18.
Name the following:
(a) The semi-dwarf variety of wheat is high-yielding and disease-resistant.
Answer:

  1. Sonalika and
  2. Kalyan Sona

(b) Anyone inter-specific hybrid mammal. (CBSE 2012)
Answer:
Mule.

Strategies for Enhancement in Food Production Important Extra Questions Short Answer Type

Question 1.
What is animal breeding? Name two main methods.
Answer:
Animal breeding: The main aim of animal breeding is to produce more milk-yielding cows with longer lactation periods and sturdier work animals. So animal breeding is an important aspect of animal husbandry. Two main methods are inbreeding and outbreeding.

Question 2.
A farmer was facing the problem of low yield from his farm. He was advised to keep a beehive in the vicinity. Why? How would the beehive help in enhancing yield?
Answer:
The honeybee is the major pollinator of several crop plants. Keeping a beehive near the farm will ensure proper pollination of crop plants. Therefore, crop yield will be ensured.

Question 3.
List three scientific approaches to obtain a high yield of crops.
Answer:

  1. Crop production management
  2. Crop improvement for higher yield through genetic manipulation
  3. Crop protection management.

Question 4.
List the main steps of plant breeding. (CBSE2014)
Answer:

  1. Collection of variability.
  2. Evaluation and selection of parents.
  3. Cross-hybridisation among selected parents.
  4. Selection and testing of superior recombinations.
  5. Testing, release, and commercialization of new cultivars.

Question 5.
Suggest two features of plants that will prevent insect and pest infestation.
Answer:

  1. Increasing hair growth on aerial parts of plants.
  2. Rendering the flowers nectar less.
  3. Enabling plants to secrete insect-killing chemicals (toxins).

Question 6.
Briefly explain hybridization. Give one example.
Answer:
For the process of hybridization, selected parents are crossed to combine useful characters in the progeny. Heterosis is exploited in augmenting yields in several commercial crops. A high-yielding variety of wheat is a classical example of hybridization in crop evolution.

Question 7.
How is a disease-resistant plant selected for successful breeding? (CBSE Delhi 2013)
Answer:
Successful breeding for disease resistance depends mainly on two factors:

  1. A good source of resistance.
  2. A dependable disease test.

Question 8.
Define germplasm. How is it maintained? (CBSE Delhi 2014)
Answer:
Germplasm is the sum total of all the alleles of the genes present in a crop and its related species. Germplasm collections are usually maintained at low temperatures in the form of seeds. In the case of fruit trees, the germplasm is maintained as trees grown in the field.

Question 9.
Name any five varieties of crop plants that have been developed in India.
Answer:

  1. Himgiri variety of wheat.
  2. Pusa Swarnim variety of Brassica.
  3. Pusa Shubhra variety of Cauliflower.
  4. Pusa Komal variety of Cowpea.
  5. Pusa Sadabahar variety of Chilli.

Question 10.
What is inbreeding depression and how is it caused in organisms? Write any two advantages of inbreeding. (CBSE Delhi 2011)
Or
Explain inbreeding depression. (CBSE Delhi 2011)
Answer:
Inbreeding depression. Continued inbreeding especially close inbreeding, usually reduces fertility and even productivity. It is termed inbreeding depression.

Advantages of inbreeding:

  1. Evolve and maintain a pure line in any animal.
  2. It helps in the accumulation of superior genes and the elimination of less desirable genes.

Question 11.
List the four objectives with which bio-fortification has been carried out to improve public health. (CBSE Delhi 2019 C)
Answer:
The method of breeding crops with higher levels of vitamins and minerals or higher protein and healthier fats is called biofortification. It is one of the most important methods for improving public health.

Objective:

  • In the recent past, many varieties of crop plants such as rice, carrots, spinach, pumpkin, and bathua have been developed which possess several times more nutritive value and vitamins as compared to existing varieties.
  • High protein content and quality
  • High oil content and quality
  • Micronutrient and minerals content.

Question 12.
Why is animal husbandry essential?
Or
What are the objectives of animal breeding? (CBSE 2014)
Answer:

  • To increase milk production.
  • To increase egg production.
  • To increase meat production.
  • To increase fish production.
  • For proper utilization of animal wastes.

Question 13.
(a) What is the breeding of crops for enhancing their nutritional value called? Why is the need felt for enhancing the nutritional value of the crops?
Or
How have these grains improved in their nutritional value in comparison to their conventional varieties? (CBSE Outside Delhi 2019)
Answer:
Iron-fortified rice variety contains over five times as much iron as compared to commonly consumed rice.

(b) Rice, wheat, and maize are the most commonly used food grains the world over.
Answer:

  1. Iron-fortified rice variety contains over five times as much iron as compared to commonly consumed rice.
  2. Wheat variety Atlas-66 has huge protein content.
  3. Maize hybrids have twice the amount of lysine and tryptophan amino acid.

Question 14.
Name any two common Indian millet crops. State one characteristic of millets that has been improved as a result of hybrid breeding to produce high-yielding millet crops. (CBSE Delhi 2015)
Answer:
Hybrid varieties of maize, Jower, and Bajra have been developed in India by plant breeders. Hybrid breeding has led to the development of several high-yielding varieties resistant to water stress.

Question 15.
Enumerate four objectives for improving the nutritional quality of different crops for the health benefits of the human population by the process of “Biofortification.” (CBSE Delhi 2015)
Answer:
Objectives:

  • Protein content and quality.
  • Oil content and quality.
  • Vitamin content.
  • Micronutrient and mineral content.

Question 16.
(i) Why are the plants raised through
micropropagation termed as some clones 1(CBSE Outside Delhi 2015)
Answer:
Plants raised by the tissue culture method are genetically identical to the original plant from which they were grown hence called some clones.

(ii) Mention two advantages of their technique.
Answer:
(a) Plants can be produced on a commercial scale.
(b) Recovery of healthy plants from diseased plants.

Question 17.
(i) Name any two fowls other than chicken reared in a poultry farm.
Answer:
Fowls other than chickens :

  1. Turkeys,
  2. Geese,
  3. Swans,
  4. Guinea fowls,
  5. Peafowls.

(ii) Enlist four important components of poultry farm management. (CBSE Delhi 2016)
Answer:
Important components of poultry farm management:
(a) Selection of disease-free and suitable breeds.
(b) Brood house should be crowd-free.
(c) Sanitation and hygiene. The brooding house should be cleaned, disinfected, and with the proper drainage system.
(d) Care of chicken during brooding.

Question 18.
Explain the process of artificial hybridization to get improved crop variety in
(i) plants bearing bisexual flowers and
Answer:
In plants bearing bisexual flowers, the anthers are removed from the flower before they dehisce. This is called emasculation. The emasculated flowers are covered with a bag of butter paper to prevent contamination of stigma with unwanted pollen. This process is called bagging. When this stigma attains receptivity, mature pollen grains are dusted on the stigma and the flowers are rebagged to allow the fruits to develop.

(ii) female parent producing unisexual flowers. (CBSE Outside Delhi 2010)
Answer:
If the female parent produces unisexual flowers, emasculation is not done. The flower buds are bagged before the flowers open. When the stigma becomes receptive, pollen is dusted on the stigma and the flower is rebagged.

Question 19.
(i) Mention the property that enables the explants to regenerate into a new plant.
Answer:
Totipotency is the ability of a cell to grow or generate the whole plant.

(ii) A banana herb is virus-infected. Describe the method that will help in obtaining healthy banana plants from this diseased plant. (CBSE Outside Delhi 2010, Delhi 2019)
Answer:
Healthy banana plants can be obtained from diseased plants by meristem culture. Although the plant is virus-infected, the apical and axillary meristems are free of virus. The meristem is removed from the plant and is grown in vitro by micropropagation. The plants produced are virus-free.

Question 20.
You have obtained a high-yielding variety of tomatoes. Name and explain the procedure that ensures retention of the desired characteristics repeatedly in large populations of future generations of the tomato crop. (CBSE Delhi 2018)
Answer:
The retention of the desired characteristics in a large population of crops can be done by micropropagation, which is a type of vegetative propagation.

In this process, a small part of the plant is excised and grown under a sterile condition in a special nutrient medium to obtain many such plants that would be genetically identical to the original plants.

Question 21.
A herd of cattle is showing reduced fertility and productivity. Provide one reason and one suggestion to overcome this problem. (CBSE Delhi 2017)
Answer:
The cattle’s productivity is decreased due to inbreeding depression. A single outcross, i.e. breeding with animals of the same breed but should not have a common ancestor on either side up to 4-6 generations, can restore its fertility.

Question 22.
Why are microbes like Spirulina being produced on a commercial scale? Mention its two advantages. (CBSE Delhi 2018C)
Answer:
25% of the human population suffers from hunger and malnutrition. Single-cell protein (SCP) is the solution to this problem. Spirulina is a rich source of protein, so it is grown on a commercial scale for SCP production.

Advantages:

  1. It utilizes cheap substrate like raw material like animal manure, wastewater from potato processing plants, straw molasses, and even sewage, therefore incidentally cleaning the environment and reducing pollution.
  2. A small amount of microbe can produce a huge quantity of protein.

Question 23.
“Modern methods of breeding animals and plants can alleviate the global food shortage”. Comment on the statement and give suitable examples.
Answer:
Several new techniques like inbreeding, outbreeding, artificial insemination, MOET, somatic hybridization, and tissue culture are playing important role in enhancing global food production. Because all these techniques aim at increasing productivity.

Strategies for Enhancement in Food Production Important Extra Questions  Long Answer Type

Question 1.
What is apiculture? How is it important in our lives? (CBSE Delhi 2019 C)
Or
Beekeeping practice is a good income-generating industry. Write the different points to be kept in mind for successful beekeeping. Write the scientific name of the most common Indian species used for the purpose. (CBSE Delhi 2019)
Answer:
Apiculture is the maintenance of hives of honeybees for commercial purposes. It is also called Beekeeping. Apiculture is very important in our lives because it produces products of high economic and nutritive value:

  1. The main product of beekeeping is honey which is a highly nutritious edible product. It replaces the use of sugar in many industries.
  2. Honey is used as a part of many indigenous medicines.
  3. Another product called beeswax is also produced which is used in the cosmetic and polish industry.
  4. Honeybees are chief pollinating agents so helpful in improving the plant yield.
  5. The most commonly used species in the wild state is Apis Indica and in the domestic state Apis mellifera.

Question 2.
What is plant breeding? (CBSE Delhi 2013)
Answer:
Plant breeding is the genetic improvement of the crop in order to create desired plant types that are better suited for cultivation, give better yields, and are disease resistant. Conventional plant breeding is in practice from 9,000 to 11,000 years ago. Most of our major food crops are derived from domesticated varieties.

But now due to advancements in genetics, molecular biology, and tissue culture, plant breeding is being carried out by using molecular genetic tools. Classical plant breeding includes hybridization (crossing) of pure lines, artificial selection to produce plants with desirable characters of higher yield, nutrition, and resistance to diseases.

Question 3.
What is a hybrid? Explain the procedure of obtaining a hybrid.
Answer:
Hybrid: A progeny obtained by crossing two varieties or species having desired genes thus showing required characters.

Process of hybridization:
This technique involves the following steps:

  1. Removal of undehisced anthers from the bisexual flower of a plant to be used as female. This is called emasculation.
  2. The emasculated flowers are covered by butter paper to avoid pollination by an undesirable pollen grain. It is also termed bagging.
  3. Pollen grains from known seeds of desirable plants are used to pollinate these emasculated flowers.
  4. They are collected, multiplied and their desirable characters are determined.

Question 4.
(i) Give the scientific name of the soil bacterium which produces crystal (Cry) proteins.
Answer:
A soil bacterium Bacillus thuringiensis (Bt) produces a crystal (Cry) protein.

(ii) How are these proteins useful in agriculture?
Answer:
A crop expressing cry gene is usually resistant to a group of insects for which the concerned Cry protein is toxic.

(iii)What do the different written terms “Cry” and “cry” represent respectively?
Answer:
The first letter of the protein symbol is always capital and always written in roman letters, i.e. Cry. However, the gene symbol usually has small letters and written in italics, i.e. cry. So Cry represents protein and cry represents a gene.

Question 5.
Differentiate between inbreeding and outbreeding in cattle. State one advantage and one disadvantage for each one of them. (CBSE Delhi 2013)
Or
How is inbreeding advantageous as well as disadvantageous in cattle breeding programs? (Mention any two advantages and two disadvantages.) (CBSE Sample Paper 2019-20)
Answer:
Differences between inbreeding and outbreeding:

Inbreeding

Outbreeding
1. Breeding between animals of the same breed for 4-6 generations. 1. Breeding between unrelated animats.
2. Continuous inbreeding leads to inbreeding depression, i.e. reduced fertility and productivity. 2. It leads to heterosis or hybrid vigor.
3. Advantages of inbreeding: It helps in restoring fertility and yield. 3. Advantage of outbreeding: It causes hybrid vigor.
4. Disadvantages of inbreeding: Continued inbreeding reduces fertility and even productivity. It is called inbreeding depression. 4. Disadvantage of outbreeding: It is costly and a difficult procedure.

Question 6.
What are superovulation and embryo transfer?
Or
Explain the strategy used for herd improvement in cattle. (CBSE Delhi 2019 C)
Or
Expand MOET. Explain the procedure of this technology in cattle improvement. (CBSE Delhi 2008, 2012, Outside Delhi 2019)
Answer:
MOET (Multiple Ovulation and Embryo Transplantation Technique). It is the latest technique to produce super milch cows.

  1. Superovulation: It involves the stimulation of high milk-producing cows to ovulate more eggs by hormonal stimulation. Fertilization is done by artificial insemination. In this way, 4 to 10 embryos are developed in such cows.
  2. Embryo transfer: In this, embryos are collected from superovulated cows. Each embryo is transplanted in the uterus of surrogate cows of inferior quality to produce a large number of calves with good germplasm. It can also be done in sheep, goats, and other livestock animals as well.

Question 7.
Why does a beekeeper keep beehives in crop fields during the flowering periods? State any two advantages. (CBSE Sample Paper)
Or
Honey collection improves when beehives are kept in crop fields during the flowering season. Explain. (CBSE 2010)
Answer:

  1. Bees act as pollinating agents.
  2. Bees bring about cross-pollination. Thus the productivity of crops increases. This in turn is beneficial to bees too as they get nectar to make honey.

Question 8.
Give a brief account of the cultivation of sugarcane and millets. (CBSE Delhi 2011, 2015)
Or
Write the scientific name of the sugarcane variety that was originally grown in North India. Why was this variety hybridized with the tropical variety of sugarcane grown in South India? (CBSE Delhi 2019 C)
Answer:
Cultivation of sugarcane:

  1. Saccharum Barberi, originally grown in North India, had poor sugar content.
  2. Saccharum officinarum, grown in South India, has thicker stems and higher sugar content but could not grow properly in North India.
  3. A cross has been made between these species and the hybrid variety, combining the desirable qualities like thick stem, high sugar content, and higher yield is being grown in North India.

Cultivation of millets:

  1. Several hybrid varieties of maize, bajra, and Jowar have been developed in India.
  2. These breeding programs have resulted in the development of high-yielding varieties that are resistant to water stress.

Question 9.
Explain out-breeding, out-crossing, and cross-breeding practices in animal husbandry. (CBSE Delhi 2018)
Or
Differentiate between out-crossing and cross breeding. (CBSE Delhi 2018C)
Answer:
Out-breeding: Out-breeding is the breeding of unrelated animals, which may be between individuals of the same breed but having no common ancestors for 4-6 generations or between different breeds or different species.

Out-crossing: Out-crossing is the practice of mating animals within the same breed, but having no common ancestors on either side of their pedigree, up to 4-6 generations. It is the best breeding method for animals that are below average in milk productivity.

Cross-breeding: Cross-breeding allows the desirable qualities of two different breeds to be combined. In this method, superior males of one breed are mated with superior females of another breed. The progeny hybrid animals may be used for commercial production or they may be subjected to some form of inbreeding and selection to develop new stable breeds that may be superior to the existing breeds. Many new animal breeds have been developed by this approach.

Question 10.
(i) Write the desirable characters a farmer looks for in his sugarcane crop,
Answer:
The desirable characters that should be present in the sugarcane crop are:
(a) High yield,
(b) thick stem,
(c) high sugar content and
(d) ability to grow in North India.

(ii) How did plant breeding techniques help north Indian farmers to develop cane with desired characters? (CBSE Delhi 2017)
Answer:
Cultivation of sugarcane:

  1. Saccharum Barberi, originally grown in North India, had poor sugar content.
  2. Saccharum officinarum, grown in South India, has thicker stems and higher sugar content but could not grow properly in North India.
  3. A cross has been made between these species and the hybrid variety, combining the desirable qualities like thick stem, high sugar content, and higher yield is being grown in North India.

Cultivation of millets:

  1. Several hybrid varieties of maize, Bajra, and Jowar have been developed in India.
  2. These breeding programs have resulted in the development of high-yielding varieties that are resistant to water stress.

Question 11.
(i) Lifestyle diseases are increasing alarmingly in India. We are also dealing with large-scale malnutrition in the population. Suggest a process by which we can address both these problems.
Answer:
These problems can be addressed by the process termed biofortification,

(ii) Give any three examples to support your answer. (CBSE Sample Paper 2018-19)
Answer:
Biofortification can be done:
(a) by enhancing food quality with respect to protein, e.g. improved wheat, maize varieties, etc.
(b) by cultivating vitamin-enriched vegetables, e.g. vitamin A enriched carrots, spinach, pumpkin, etc
(c) by enriching micronutrient and mineral content in vegetables, e.g. iron and calcium-enriched spinach and bathua

Question 12.
What is biofortification? Mention the contribution of the Indian Agricultural Research Institute towards it with the help of any two examples. (CBSE Delhi 2018C)
Answer:
It is an improvement in the nutritional quality of food crops by breeding. Through this, levels of vitamins, minerals, proteins, and healthier fats are enriched in crops. Indian Agricultural Research Institute released several vitamin and mineral enriched vegetable crops like vitamin A enriched carrots and spinach; Vitamin C enriched bitter guard, mustard, tomato; iron and calcium-enriched spinach and bathua; protein-enriched broad lablab, French and garden peas.

Question 13.
(i) What is artificial insemination? Give its significance.
Answer:
Artificial insemination:

  • It is the process in which the semen collected from a superior quality male is injected into the reproductive tract of the selected female by the breeder.
  • The advantages of artificial insemination are as follows:
  • Semen can be used immediately or stored/frozen and used at a later date when the female is in the right reproductive phase.
  • Semen can be transported in the frozen form to a distant place where the selected female animals are present.
  • Semen from one selected male animal can be used on a number of female animals.
  • The disadvantage is that the success rate is fairly low.

(ii) Write a note on MOET. (CBSE Delhi 2008)
Answer:
Multiple Ovulation Embryo Transfer Technology (MOET):

  1. It is a method to improve the herds and their size.
  2. The steps in the method are as follows:
  3. A cow is administered hormones (like FSH) to induce follicular maturation and superovulation, i.e. production of 6-8 ova in one cycle.
  4. The cow is mated with the selected bull or artificially inseminated.
  5. The fertilized eggs at 8-32 celled stages are recovered and transferred to surrogate mothers.
  6. This technology has been used for cattle, rabbits, mares, etc.
  7. High milk-yielding breeds of females and high-quality meat-yielding bulls have been bred successfully to increase the herd size in a short time.

Significance:

  • Several cows (up to 3,000) can be inseminated by the semen of a single pedigree bull of good quality.
  • Avoid the transportation of animals,
  • The quality and quantity of progeny can be improved.
  • New characters can be introduced in the progeny.
  • It is economical.

Question 14.
What are the practices adopted to improve crop production?
Answer:
The practices adopted to improve crop production are as follows:

  1. Addition of fertilizers to the soil.
  2. Selective breeding.
  3. Weed control.
  4. Control of plant diseases.
    (a) Fertilisers: These are the chemical compounds that are added to the soil to increase fertility. They make up for the deficiency of the required nutrients and help in increasing crop production.
    (b) Selective breeding: Disease-resistant seeds are produced by selective breeding. Regular use of high yield variety results in better crop production.
    (c) Weed control: The unwanted plants or weeds are controlled by using certain chemicals called weedicides.
    (d) Control of plant diseases: Crops should be protected from insects, fungi, animals, and other diseases. It is very useful for increasing crop production. Insects are very harmful to crops. So insecticides should be used to kill insects.

Question 15.
Discuss the role of plant tissue culture in increasing food production. (CBSE Delhi 2011)
Answer:
Applications of tissue culture technique:

  1. This technique is applied for the rapid multiplication of desirable and rare plants.
  2. By this technique, an indefinite number of plants can be produced.
  3. From the culturing of virus-free tissues of the shoot apex of an infected plant, it becomes possible to obtain virus-free plant in sufficient stock. The tissue culture technique has been used to obtain virus-free potatoes and sugarcane.
  4. The technique (Embryo culture) is useful in overcoming seed dormancy, but also in producing viable plants from the crosses which normally fail due to the death of immature embryos.
  5. The technique has been applied for obtaining a large number of haploid and homozygous diploids.
  6. Somatic hybridization helps the fusion of cells belonging to different families.
  7. This technique is also useful for the genetic improvement of useful plants.

Question 16.
“The benefits of a new variety can be achieved only if farmers grow the variety”. Explain.
Answer:
The seed of new variety must be multiplied and made available to the farmers. In-plant breeding, seed means any plant part that is used to grow a crop. Thus ‘seed’ would include grains of wheat, rice, etc. tubers of the potato, stems of sugarcane, etc., provided they are used for producing new plants.

Therefore, wheat grains used as food cannot be termed as seeds, whereas those used for raising a crop are called seeds. A seed of a variety with superior traits is called an improved seed, which must be of high purity and have a high germination percentage. It must also be free from weed seeds and from diseases.

Question 17.
(a) What is mutation breeding? Give an example of a crop and disease to which resistance was induced by this method.
Answer:
(a) Mutation breeding involves the following steps:

  1. Inducing mutation(s) through various methods/ mutagens.
  2. Screening the plant materials for disease resistance.
  3. Multiplication of these selected plants for direct use or for use inbreeding.
  4. Hybridization of the selected plant materials.
  5. Selection for disease resistance, testing, and release as a variety.
  6. Through mutation breeding, varieties of mung bean have been developed that are resistant to yellow mosaic virus and powdery mildew.

(b) Differentiate between pisciculture and aquaculture. (CBSE Sample Paper 2020)
Answer:

Aquaculture

Pisciculture
It involves the rearing all types of aquatic organisms to obtain products of economic value. Pisciculture involves the rearing of fishes for obtaining food and fishery by-products such as fish oil, fish glue, fish manure, shagreen, leather, etc.

Question 18.
How can crop varieties be made disease resistant to overcome the food crisis in India? Explain. Name one disease-resistant variety in India of:
(i) Wheat to leaf and stripe rust
Answer:
Mutation breeding involves the following steps:
(a) Inducing mutation(s) through various methods/mutagens.
(b) Screening the plant materials for disease-resistance.
(c) Multiplication of these selected plants for direct use or for use inbreeding.
(d) Hybridisation of the selected plant materials.
(e) Selection for disease resistance, testing, and release as a variety.
(e) Through mutation breeding, varieties of mung bean have been developed that are resistant to yellow mosaic virus and powdery mildew.

(ii) Brassica to white rust (CBSE 2011)
Answer:
(a) Himgiri variety of wheat
(b) Pusa swarm of Brassica

Question 19.
(i) Name the technology that has helped the scientists to propagate on a large scale the desired crops in a short duration. List the steps carried out to propagate the crops by the said technique.
(ii) How are somatic hybrids obtained?
Or
Scientists tried to develop a single plant exhibiting the characteristic of tomato and potato by using cells from tomato and potato plants respectively. Name the procedure and list the steps to achieve this. (CBSE Delhi 2014, Outside Delhi 2019, Sample Paper 2020)
Answer:
1. Tissue culture:
(a) It is the technique of regeneration of whole plants from any part of a plant by growing it on a suitable culture/nutrient medium under aseptic/sterile conditions in vitro.
(b) The culture medium must supply the energy, inorganic nutrients, vitamins, amino acids, and growth regulators like cytokinins and auxins.
(c) By this method, called micropropagation, thousands of plants can be grown in a short period of time.

The advantages of micropropagation are:
(a) The plants produced are genetically identical and constitute some clones.
(b) A number of plants can be grown in a short period of time.
(c) Healthy, disease-free plants can be grown by meristem culture.
(d) Somatic hybrids can be raised by tissue culture, where sexual hybridization is not possible.

2. Somatic Hybridization: Fusion of isolated protoplasts from two different plant varieties each having desirable characters is called somatic hybridization. The resultant hybrid is called somatic hybrids. This somatic hybrid can be grown into a new plant carrying all desirable qualities.