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Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 16 Environmental Issues. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Environmental Issues MCQs Pdf with Answers to know their preparation level.

Environmental Issues Class 12 Biology MCQs Pdf

1. The thickness of ozone is measured as
(a) parts per billion
(b) Dobson units
(c) parts per million
(d) decibel.

Answer

Answer: b

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2. Polyblend was first developed by
(a) Ramesh Chandra Dagar
(b) Ahmed Khan
(c) KhadiandVillagelndustriesCommission
(d) Indian Institute of Science.

Answer

Answer: b

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3. Good ozone is found in the
(a) stratosphere
(b) troposphere
(c) mesosphere
(d) ionosphere.

Answer

Answer: a

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4. Eutrophication causes a/an
(a) decrease in organic matter
(b) increase in inorganic nutrients
(c) decrease in dissolved oxygen
(d) increase in dissolved oxygen.

Answer

Answer: c

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5. Increase in cases of skin cancer and high mutation rate are the result of
(a) ozone depletion
(b) acid rain ,
(c) CO₂ pollution
(d) CO pollution

Answer

Answer: a

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6. Increase in the concentration of pollutants/chemicals in higher trophic levels, is known as
(a) biodegradation
(b) eutrophication
(c) greenhouse effect
(d) biomagnification

Answer

Answer: d

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7. Ozone hole is the largest over
(a) Africa
(b) Antarctica
(c) America
(d) Europe

Answer

Answer: b

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8. Phosphate pollution in a waterbody is brought about by
(a) phosphate rock weathering
(b) fertilizers
(c) phosphate rocks and sewage
(d) fertilizers and sewage.

Answer

Answer: d

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9. Which of the following causes biomagnifi¬cation?
(a) SO₂
(b) Mercury
(c) DDT
(d) Both (b) and (c)

Answer

Answer: d

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10. Catalytic converters are fitted into automobiles to reduce emission of harmful gases. Catalytic converters change unbumt hydrocarbons into [NCERT Exemplar]
(a) carbon dioxide and water
(b) carbon mono oxide
(c) methane
(d) carbon dioxide and methane.

Answer

Answer: a

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11. Nuisance growth of aquatic plants and bloom-forming algae in natural waters is generally due to high concentrations of [NCERT Exemplar]
(a) carbon
(b) sulphur
(c) calcium
(d) phosphorus

Answer

Answer: d

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12. Which one of the following impurities is easiest to remove from wastewater? [NCERT Exemplar]
(a) Bacteria
(b) Colloids
(c) Dissolved solids
(d) Suspended solids

Answer

Answer: d

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13. According to Central Pollution Control Board (CPCB), particulates of size ______ or more in diameter are responsible for causing harm to human health.

Answer/Explanation

Answer:
Explaination: 2.5 micrometres

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14. The discharge of domestic sewage into a river will decrease the ______ of the waterbody.

Answer/Explanation

Answer:
Explaination: Dissolved oxygen.

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15. A mere ______ per cent impurities makes the domestic sewage unfit for human use.

Answer/Explanation

Answer:
Explaination: 0.1

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16. Inflammation of cornea, called ______ is caused by UV-B radiation.

Answer/Explanation

Answer:
Explaination: Snow blindness.

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17. ______ gas is continuously produced by the action of UV rays on molecular oxygen.

Answer/Explanation

Answer:
Explaination: SOzone.

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18. ______ per cent of the forests have been lost in the tropics.

Answer/Explanation

Answer:
Explaination: 40.

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19. ______ cultivation in the north-eastern states of India has also contributes to deforestation.

Answer/Explanation

Answer:
Explaination: Jhum.

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20. Faecal matter, paper fibres, bacteria and cloth fibres are the ______ material present in sewage water.

Answer/Explanation

Answer:
Explaination: Colloidal.

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21. Excess growth of ______ algae causes algal bloom in eutrophied waterbodies.

Answer/Explanation

Answer:
Explaination: Planktonic.

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22. Euro II norms stipulate that sulphur be controlled at ______ in diesel.

Answer/Explanation

Answer:
Explaination: 350 ppm.

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23. Match the Government initiatives to reduce pollution in Column I with the year in which they into effect in Column II.

Column I	Column II
A. Air  (Prevention and Control of Pollution) Act	1. 1974
B. Joint Forest Management water	2. 1986
C. Water (Prevention and Control Pollution) Act	3. 1980
D. Environment (Protection) Act	4.1981

Answer/Explanation

Answer:
Explaination: A – 4, B – 3, C – 1, D – 2

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24. Match the DDT concentration in Column I with the organisms in an aquatic food chain in Column II.

Column I	Column II
A. 0.04 ppm	1. Large fish
B. 2.0 ppm	2. Zooplanktons
C. 0.5 ppm	3. Fish-eating birds
D. 25 ppm	4. Small fish

Answer/Explanation

Answer:
Explaination: A – 2, B – 1, C – 4, D – 3

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25. The Montreal Protocol is associated with the control of emission of ozone-depleting substances. [True/False]

Answer/Explanation

Answer:
Explaination: True.

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26. Dobson units are used to measure oxygen content in waterbodies. [True/False]

Answer/Explanation

Answer:
Explaination: False.

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27. A brief exposure to high level sound, 150 dB or more can damage the ear drum.[True/False]

Answer/Explanation

Answer:
Explaination: True.

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28. There is a substantial fall in NO₂ and CO₂ levels in the air in Delhi between 1997 and 2005. [True/False]

Answer/Explanation

Answer:
Explaination: False.

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29. CNG can be easily siphoned off compared to petrol or diesel. [True/False]

Answer/Explanation

Answer:
Explaination: False.

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Directions (Q30 to Q32): Mark the odd one in each of the following groups.
30. Jaundice, Hepatitis B, Typhoid, Dysentery

Answer/Explanation

Answer:
Explaination: Hepatitis-B.

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31. Sand, Silt, Clay, Nitrate

Answer/Explanation

Answer:
Explaination: Nitrate.

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32. Oxygen, Carbon monoxide, Sulphur dioxide, Nitrogen oxides.

Answer/Explanation

Answer:
Explaination: Oxygen

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33. What are pollutants?

Answer/Explanation

Answer:
Explaination: Pollutants are those substances/agents which bring about undesirable changes in the properties of air, water and soil, which adversely affect the living organisms.

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34. Name the two harmless gases released by thermal power plants/smelters.

Answer/Explanation

Answer:
Explaination: Nitrogen and oxygen.

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35. Name the device used to remove
(a) particulate air pollutants
(b) pollutant gases like SO₂ from the exhaust.

Answer/Explanation

Answer:
Explaination:
(a) Electrostatic precipitator.
(b) Scrubber.

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36. An electrostatic precipitator in a thermal power plant is not able to generate high voltage of several thousands. Write the ecological implication because of it. [AI 2017]

Answer/Explanation

Answer:
Explaination: Electrostatic precipitator removes 99 per cent of the particulate matter from the exhaust from thermal plant; in its absence, the particulate matter will get into the atmosphere and cause respiratory disorders.

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37. What is the size of the particulate matter that causes the greatest harm to human health?

Answer/Explanation

Answer:
Explaination: 2.5 micrometres or less.

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38. Why is the use of unleaded petrol recommended for motor vehicles equipped with catalytic convectors? [AI 2013, 2010]
Or
Why is it desirable to use unleaded petrol in vehicles fitted with catalytic converters? [AI 2012, Foreign 2010]
Or
Why should motor vehicles equipped with catalytic converter use unleaded petrol? [Delhi 2011C]

Answer/Explanation

Answer:
Explaination: Otherwise lead will inactivate the catalyst.

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39. What is the goal of auto fuel policy of the Indian government, regarding sulphur in auto fuels?

Answer/Explanation

Answer:
Explaination: The goal is to reduce sulphur to 50 ppm in petrol and diesel and bring down the level to 35 ppm.

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40. List two advantages of the use of unleaded petrol in automobiles as fuel. [AI2015]

Answer/Explanation

Answer:
Explaination:
(i) The catalysts will not be inactivated.
(ii) There will be no lead in the exhaust from the vehicle.

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41. Why is it necessary to remove sulphur from petroleum products?

Answer/Explanation

Answer:
Explaination: There will be no oxides of sulphur in the automobile exhause; oxides of sulphur in the atmosphere cause acid rains.

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42. List two gaseous products that are produced when exhaust of an automobile passes through a catalytic converter. [Delhi 2012C]

Answer/Explanation

Answer:
Explaination: Carbon dioxide and nitrogen.

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43. When did the Air (Prevention and Control of Pollution) Act, (a) come into force and (b) when was it amended to include noise as an air pollutant?

Answer/Explanation

Answer:
Explaination:
(a) It came into force in the year 1981.
(b) It was amended in 1987 to include noise.

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44. What is noise?

Answer/Explanation

Answer:
Explaination: Noise is defined as undesirable high level of sound.

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45. What per cent of sewage water has impurities that make it unfit for human use?

Answer/Explanation

Answer:
Explaination: 0.1 percent.

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46. Given below are a few impurities in urban waste water. Select two colloidal impurities: ammonia, faecal matter, silt, bacteria, calcium.

Answer/Explanation

Answer:
Explaination: Faecal matter and bacteria.

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47. Which component in the domestic sewage is difficult to remove?

Answer/Explanation

Answer:
Explaination: The dissolved salts like nitrates and phosphates.

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48. How do algal blooms affect the life in water bodies? [AI 2011]

Answer/Explanation

Answer:
Explaination:
– Algal blooms reduce the dissolved oxygen content of the water and cause mortality (death) of aquatic animals like fish.
– They also secrete chemicals toxic to aquatic animals.

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49. Name the world’s most problematic aquatic , weed. What is the nature of the water body ’ in which the weeds grow abundantly?

Answer/Explanation

Answer:
Explaination:
– Eichhornia crassipes (water hyacinth)
– Eutrophic water bodies.

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50. Why is Eichhomia crassipes nicknamed as ‘Terror of Bengal’? [Delhi 2012]
Or
Eichhomia crassipes is an alien hydrophyte . introduced in India. Mention the problems posed by this plant. [AI 2010C]

Answer/Explanation

Answer:
Explaination:
– They grow faster than our ability to remove them and cause blocks in our waterways.
– Their abundant growth leads to an imbalance in the ecosystem dynamics of the waterbody.

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51. Name flie pollutants, the industrial waste water contains.

Answer/Explanation

Answer:
Explaination: The industrial waste water contains toxic substances like heavy metals and some organic compounds.

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52. Excessive nutrients in a fresh water body cause fish mortality. Give two reasons. [Delhi 2016]

Answer/Explanation

Answer:
Explaination:
(i) Excessive nutrients in a freshwater body stimulate the excess growth of planktonic algae, which ultimately reduce the dissolved oxygen content of the water body and cause fish mortality.
(ii) Some of these algae also secrete toxins, which lead to fish mortality.

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53. Eutrophication is the natural ageing of a lake. Mention any other feature which defines the term. [CBSE Sample Paper 2013,2014]

Answer/Explanation

Answer:
Explaination: Nutrient enrichment of water.

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54. State the cause of accelerated eutrophication. [Delhi 2014]

Answer/Explanation

Answer:
Explaination: Effluents from industries and homes.

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55. What is cultural/accelerated eutrophication?

Answer/Explanation

Answer:
Explaination: Cultural/accelerated eutrophication is a phenomenon of man-induced nutrient enrichment and accelerated ageing of the water bodies.

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56. What is the raw material for polyblend?

Answer/Explanation

Answer:
Explaination: Plastic wastes.

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57. The use of incinerators is crucial for the disposal of hospital waste. Justify [HOTS]

Answer/Explanation

Answer:
Explaination: Hospitals generate hazarduous wastes that contain harmful chemicals, disinfectants and pathogenic microbes; such wastes require disposal using incinerators.

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58. Inspite of being non-polluting, why are there great apprehensions in using nuclear energy for generating electricity? [Foreign 2014]

Answer/Explanation

Answer:
Explaination:
Because using nuclear energy has two problems.
(i) The safe disposal of nuclear wastes.
(ii) Any accidental leakage can prove to be extremely damaging to living organisms.

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59. Write in full form, the name of the organisation that makes an assessment of die greenhouse gases in the atmosphere.

Answer/Explanation

Answer:
Explaination: Intergovernmental Panel on Climate Change (IPCC).

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60. Why is the climate change expected to increase the spread of human diseases?

Answer/Explanation

Answer:
Explaination: It would increase the size of population of pathogens and their vectors.

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61. What is meant by greenhouse effect?

Answer/Explanation

Answer:
Explaination: Greenhouse effect is a naturally occurring phenomenon, in which the shortwave radiations of solar energy are absorbed and longwave radiations are reflected by the earth and is responsible for heating of earth’s surface and atmosphere.

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62. What is global warming?

Answer/Explanation

Answer:
Explaination: Global warming refers to the increase in the global mean temperature.

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63. What is the expected rise in the global temperature by die year 2100?

Answer/Explanation

Answer:
Explaination: It may rise by 1.4-5.8 °C.

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64. Name the greenhouse gases that contribute to total global wanning. [Delhi 2014]

Answer/Explanation

Answer:
Explaination: Carbon dioxide, methane, nitrous oxide and chlonofluoro carbons.

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65. Name the greenhouse gases contributing maximum to the greenhouse effect. [AI2014C]

Answer/Explanation

Answer:
Explaination: Carbon dioxide and methane.

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66. Name the layer of atmosphere that is associated with ‘good ozone’.

Answer/Explanation

Answer:
Explaination: Strastosphere.

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67. Where is good ozone present? Why is it called so? [Delhi 2014C]

Answer/Explanation

Answer:
Explaination:
– It is found in the stratosphere of the atmosphere.
– Since it acts as a shield to absorb the ultraviolet radiation from the sun, it is called good ozone.

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68 Write the unit used for measuring ozone thickness. [Delhi 2011]

Answer/Explanation

Answer:
Explaination: Dobson units (DU).

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69. Mention the causes of thinning of ozone layer. [Delhi 2010C]

Answer/Explanation

Answer:
Explaination: Chlorofluorocarbons (CFCs) release Cl atoms when UV rays act on them; Cl degrades the ozone into molecular oxygen.

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70. What is ozone shield?

Answer/Explanation

Answer:
Explaination: The thin layer of ozone in the upper part or the stratosphere of the atmosphere that prevents entry of UV rays, is called ozone shield.

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71. What is meant by ozone hole?

Answer/Explanation

Answer:
Explaination: The decline in the thickness of spring time ozone layer over Antarctica, is called ozone hole.

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72. When does the ozone hole develop over Antarctica every year?

Answer/Explanation

Answer:
Explaination: It develops each year between late August and early October.

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73. State the effect of UV-B on human eyes. [Foreign 2013]
Or
Mention two harmful effects ofUV-B exposure on human eyes. [AI 2012C]

Answer/Explanation

Answer:
Explaination:
– High dose of UV-B causes inflammation of cornea, called snow-blindness and also cataract.
– It may permanently damage the cornea.

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74. Mention the effect of UV rays on DNA and proteins in living organisms. [Foreign 2013]

Answer/Explanation

Answer:
Explaination: UV rays are preferentially absorbed by DNA and proteins of living beings; the high energy of UV rays break the chemical bonds within these molecules and causes damage to them.

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75. How is snow-blindness caused in humans? [AI 2010]

Answer/Explanation

Answer:
Explaination: Snow-blindness is caused by a high dose of UV-B radiation.

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76. State the purpose of signing the Montreal Protocol. [Foreign 2014]

Answer/Explanation

Answer:
Explaination: The purpose is to control the emission of CFCs and other ozone-depleting substances.

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77. Mention two problems (that degrade soil fertility) that have come in the wake of Green Revolution.

Answer/Explanation

Answer:
Explaination:
– Soil erosion and desertification.
– Water logging and soil salinity.

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78. What is meant by deforestation?

Answer/Explanation

Answer:
Explaination: Deforestation is the conversion of forested areas into non-forested ones.

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79. How does Jhum cultivation promote desertification? [AI 2011C]

Answer/Explanation

Answer:
Explaination: In Jhum cultivation, after cultivation, the land/area is left free for several years to allow its recovery; but with increasing demand for food, and repeated cultivation, the recovery phase is often ignored leading to deforestation.

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80. How/Why does deforestation lead to global warming?

Answer/Explanation

Answer:
Explaination: The plants which can hold a lot of carbon in their biomass are lost due to deforestation; the increased concentration of carbon dioxide in the atmosphere causes global warming.

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Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 15 Biodiversity and Conservation. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Biodiversity and Conservation MCQs Pdf with Answers to know their preparation level.

Biodiversity and Conservation Class 12 Biology MCQs Pdf

1. log S = log C + Z log A
In the given equation of species-area relationship, the value of regression coefficient for a whole continent, would be
(a) 0.1-0.2
(b) 0.5-0.7
(c) 0.6-1.2
(d) 0.3-0.5

Answer

Answer: c

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2. Which of the following organisation is responsible for maintaining the Red Data Book?
(a) IDRI
(b) IUCN
(c) UNESCO
(d) USDA

Answer

Answer: b

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3. From his long term ecosystem experiments, David Tilman showed that
(a) decreased diversity contributed to higher productivity
(b) decreased diversity contributed to decreased productivity
(c) increased diversity contributed to increased productivity
(d) increased diversity contributed to decreased productivity

Answer

Answer: c

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4. Which of the following is a hot-spot of biodiversity in India?
(a) Western Ghats
(b) Indo-gangetic plain
(c) Eastern Ghats
(d) Aravalli Hills

Answer

Answer: a

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5. Which among the following is not a method of in-situ conservation?
(a) National Park
(b) Botanical garden
(c) Wildlife sanctuary
(d) Ramsar sites

Answer

Answer: b

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6. The World Summit on Sustainable Development (2002) was held in
(a) Brazil
(b) South Africa
(c) Sweden
(d) Argentina

Answer

Answer: b

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7. The most important cause of extinction of animals and plants, especially in tropical rain forests is
(a) habitat loss
(b) afforestation
(c) pollution
(d) soil erosion

Answer

Answer: a

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8. The enormous number of varieties of mango in India represents
(a) genetic diversity
(b) species diversity 1
(c) ecological diversity
(d) hybridisation programmes

Answer

Answer: a

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9. Which one of the following is not a major characteristic feature of biodiversity hot spots? [NCERT Exemplar]
(a) Large number of species
(b) Abundance of endemic species
(c) Large number of exotic species
(d) Destruction of habitat

Answer

Answer: d

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10. Which of the following is not a cause for loss of biodiversity? [NCERT Exemplar]
(a) Destruction of habitat
(b) Invasion by alien species
(c) Keeping animals in zoological parks
(d) Over-exploitation of natural resources

Answer

Answer: c

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11. The extinction of passenger pigeon was due to [NCERT Exemplar]
(a) increased number of predatory birds.
(b) over exploitation by humans.
(c) non-availability of the food.
(d) bird flu virus infection.

Answer

Answer: b

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12. Which of the below mentioned regions exhibit less seasonal variations? [NCERT Exemplar]
(a) Tropics
(b) Temperates
(c) Alpines
(d) Both (a) & (b)

Answer

Answer: a

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13. India now has _____ wildlife sanctuaries.

Answer/Explanation

Answer:
Explaination: 448

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14. 70 per cent of the animal species recorded are _____ .

Answer/Explanation

Answer:
Explaination: Insects.

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15. ________ places the global species biodiversity at about 7 million.

Answer/Explanation

Answer:
Explaination: Robert May.

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16. The maximum diversity of amphibians in India is observed in _____ .

Answer/Explanation

Answer:
Explaination: Western Ghat.

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17. The recent introduction of Clarias gariepinus is posing threat to our indigenous _____ in our rivers.

Answer/Explanation

Answer:
Explaination: Catfishes.

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18. _____ introduced into Lake Victoria caused extinction of 200 species of cichlid fishes.

Answer/Explanation

Answer:
Explaination: Nile perch.

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19. Thylacine from _____ and quagga from Africa are examples of recent extinctions.

Answer/Explanation

Answer:
Explaination: Australia.

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20. _____ popularised the term Biodiversity.

Answer/Explanation

Answer:
Explaination: Edward Wilson.

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21. India’s share of global biodiversity is about _____ per cent.

Answer/Explanation

Answer:
Explaination: 8.1

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22. _____, the last refuges of a number of threatened species of plants, are found in Aravalli Hills of Rajasthan and Jaintia Hills of Meghalaya.

Answer/Explanation

Answer:
Explaination: Sacred groves.

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23. Match the items in Column I with those in Column II.

Column I	Column II
A. Cryopreser-vation	1. Hotspot
B. Tropical forests	2. In situ conservation
C. Endemism	3. Ex situ conservation
D. Lantana	4. Coevolution
E. Plant-pollinator mutualifls	5. Habitat loss
F. Wildlife sanctuary	6. Alien species
	7. Stellar’s Sea cow

Answer/Explanation

Answer:
Explaination: A – 3, B – 5, C – 1, D – 6, E – 4, F – 2

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24. Match the items in Column I with those in Column II.

Column I	Column II
A. Narrowly utilitarian	1. Passenger pigeon
B. Broadly  utilitarian	2. Tannins, Resins of plants
C. The Earth Summit	3. Pollination of plants
D. Over- exploitation	4. Rio de Janeiro, in 1992
	5. Ethical Arguments

Answer/Explanation

Answer:
Explaination: A – 2, B – 3, C – 4, D – 1

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25. Parthenium is an endemic species of our country. [True/False]

Answer/Explanation

Answer:
Explaination: False.

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26. Stellar’s sea cow is an extinct animal. [True/False]

Answer/Explanation

Answer:
Explaination: True.

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27. India is one of the mega diversity countries of the world. [True/False]

Answer/Explanation

Answer:
Explaination: True.

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28. 20 per cent of the total oxygen in the earth’s atmosphere is produced by temperate forests like Amazon forest. [True/False]

Answer/Explanation

Answer:
Explaination: True.

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29. Endemic species are those which are distributed in almost all parts on the globe. [True/False]

Answer/Explanation

Answer:
Explaination: False.

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Directions (Q30 to Q33): Mark the odd one in each of the following groups.
30. Parthenium, Mangifera, Lantana Eichhornia

Answer/Explanation

Answer:
Explaination: Mangifera.

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31. Bali, Javan, Caspian, Dodo

Answer/Explanation

Answer:
Explaination: Dodo.

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32. Seed banks, Tissue culture, Sacred groves, Cryopreservation

Answer/Explanation

Answer:
Explaination: Sacred groves.

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33. Aravalli Hills, Chanda and Bastar, Khasi Hills, Zoological park

Answer/Explanation

Answer:
Explaination: Zoological park.

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34. Name the type of biodiversity represented by the following:
(a) 50,000 different strains of rice in India.
(b) Estuaries and alpine meadows in India. [Delhi 2013]
Or
India has more than 50,000 strains of rice. Mention the level of biodiversity it represents. [AI2010]

Answer/Explanation

Answer:
Explaination:
(a) Genetic diversity.
(b) Ecological diversity.

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35. Name the type of biodiversity represented by the following:
(a) 1000 varieties of mango in India.
(b) Variations in terms of potency and concentration of reserpine in Rauwolfia vomitoria growing in different regions of Himalayas. [AI 2013]

Answer/Explanation

Answer:
Explaination:
(a) Genetic diversity
(b) Genetic diversity

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36. Write the level of biodiversity represented by a mangrove. Give another example falling in the same level. [AI 2014C]

Answer/Explanation

Answer:
Explaination:
– Ecological diversity.
– Coral reefs/wet lands/estuaries/alpine meadows.

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37. Why is genetic variation important in the plant Rauwolfia?

Answer/Explanation

Answer:
Explaination: Genetic variation in Rauwolfia is shown in terms of potency and concentration of the active chemical, reserpine produced by the plant.

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38. Why is India said to have greater ecosystem diversity than Norway? [Delhi 2012C]

Answer/Explanation

Answer:
Explaination: India has much of its land in the tropical latitudes and has a number of ecosystems like deserts, mangroves, rain forests, coral reefs, wetlands and estuaries; hence, it has greater ecosystem diversity whereas Norway is located in the temperate latitudes and hence, shows less diversity.

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39. Define species diversity..

Answer/Explanation

Answer:
Explaination: The diversity at the species level (types and numbers), is called species diversity.

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40. Which region in India has the maximum number of amphibian species?

Answer/Explanation

Answer:
Explaination: Western Ghats.

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41. Identify ‘a’ and ‘b’ in the figure given below representing proportionate number of major vertebrate taxa. [Delhi 2014]

Answer/Explanation

Answer:
Explaination:
‘a’ – Mammals,
‘b’ – Amphibians.

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42. Name the unlabelled areas ‘a’ and ‘b’ of the pie chart (given) representing the global biodiversity of invertebrates showing their proportionate number of species of major taxa.

Answer/Explanation

Answer:
Explaination:
‘a’ – Insects;
‘b’ – Molluscs.

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43. Name the unlabelled areas ‘a’ and ‘b’ of the pie chart representing the biodiversity of plants showing their proportionate number of species of major taxa.

Answer/Explanation

Answer:
Explaination:
‘a’ – Fungi,
‘b’ – Angiosperms.

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44. Which region of the earth has the greatest biodiversity on earth?

Answer/Explanation

Answer:
Explaination: Amazonian rain forest.

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45. What is the general range of the value of slope of the line of regression for any taxa in any region?

Answer/Explanation

Answer:
Explaination: 0.1 to 0.2.

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46. Name one animal species that has become ‘extinct recently each in
(a) Australia and
(b) Mauritius, respectively.

Answer/Explanation

Answer:
Explaination:
(a) Thylacine.
(b) Dodo.

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47. What per cent of the earth’s surface was covered by tropical rain forests at
(a) the beginning of 20th century and
(b) now, respectively?

Answer/Explanation

Answer:
Explaination:
(a) 14%
(b) 6%.

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48. The Amazon rain forest is referred to as ‘the lungs of the planet’. Mention any one human activity which causes loss of biodiversity in this region. [AI 2010C]

Answer/Explanation

Answer:
Explaination:
(i) Many plants are cut and the land is cleared for cultivation of soyabean.
(ii) Conversion of forest land into grassland for raising beef cattle. (any one)

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49. What is the main reason for the extinction of passenger pigeon?

Answer/Explanation

Answer:
Explaination: Over exploitation by humans.

---

50. What is common about Eichhornia, Lantana and Parthenium with reference to threat to our biodiversity?

Answer/Explanation

Answer:
Explaination: They are exotic species, introduced into India; these alien species have caused environmental damage and posed threat to our native species.

---

51. About 200 species of Cichlid fish became extinct when a particular fish was introduced in lake Victoria of Africa. Name the invasive fish.

Answer/Explanation

Answer:
Explaination: The Nile perch.

---

52. What is meant by threatened species?

Answer/Explanation

Answer:
Explaination: Threatened species are those organisms facing a very high risk of extinction in the wild in the near future.

---

53. What is the total number of hot spots in the world? How many of them are there in India?

Answer/Explanation

Answer:
Explaination:
– There are 34 hot spots in the world.
– Three are in India.

---

54. When was Ramsar Convention developed and adopted and when did it come into force?

Answer/Explanation

Answer:
Explaination: It was developed in 1971 and came into force from December, 1975.

---

55. What is the mission of Ramsar Convention?

Answer/Explanation

Answer:
Explaination: The mission of Ramsar convention is the conservation and wise use of wetlands through local and national actions and international cooperation and achieve sustainable development of wetlands throughout the globe.

---

56. Name the country that has the
(a) highest number of Ramsar sites
(b) greatest area of listed wetlands in the world, as on November 2013.

Answer/Explanation

Answer:
Explaination:
(a) England
(b) Canada

---

57. How many national parks and wildlife sanctuaries are there in India?

Answer/Explanation

Answer:
Explaination:
90 national parks and 448 wildlife sanctuaries are there in India.

---

58. Why have Western Ghats in India been declared as biological hot spots? [AI 2015C]

Answer/Explanation

Answer:
Explaination: It is because this region has a very high level of species richness and endemism.

---

59. Name any two conventional methods of ex situ conservation.

Answer/Explanation

Answer:
Explaination: Botanical gardens, wildlife safaris and zoos are the conventional ex situ strategies. (any two)

---

60. Write the importance of cryopreservation in conservation of biodiversity. [Delhi 2011]

Answer/Explanation

Answer:
Explaination: It is an ex situ method of biodiversity conservation in which gametes of threatened species can be preserved in viable and fertile conditions for long periods.

---

We hope the given Biology MCQs for Class 12 with Answers Chapter 15 Biodiversity and Conservation will help you. If you have any query regarding CBSE Class 12 Biology Biodiversity and Conservation MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 13 Organisms and Populations. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Organisms and Populations MCQs Pdf with Answers to know their preparation level.

Organisms and Populations Class 12 Biology MCQs Pdf

1. Animals from colder climates generally have shorter limbs. This is called
(a) Allen’s rule
(b) Johnson’s rule
(c) Arber’s rule
(d) Niche rule

Answer

Answer: a

---

2. Niche is defined as
(a) a component of an ecosystem
(b) an ecologically adapted zone of a species
(c) the physical position and functional role of a species within the community
(d) all plants and animals living at the bottom of a water body.

Answer

Answer: c

---

3. It natality is balanced by mortality in a population at a given time, there will be a/an
(a) decrease in the population size
(b) increase in the population size
(c) zero population growth
(d) population explosion

Answer

Answer: c

---

4. Mycorrhiza is an example of
(a) ectoparasitism
(b) mutualism
(c) endoparasitism
(d) predation

Answer

Answer: b

---

5. The interspecific interaction in which one partner is benefitted and the other is unaffected (neutral), is called
(a) amensalism
(b) mutualism
(c) competition
(d) commensalism

Answer

Answer: d

---

6. Individuals of one kind, i.e., one species occupying a particular geographic area, at a given time form a/an
(a) community
(b) biome
(c) population
(d) deme

Answer

Answer: c

---

7. The formula of exponential population growth curve, is
(a) dN/dt = rN
(b) dt/dN rN
(c) dN/rN = dt
(d) rN/dN = dt

Answer

Answer: a

---

8. Niche overlap indicates
(a) mutualism between two species
(b) active cooperation between two species
(c) sharing of one or more resources between the two species
(d) two different parasites on the same host.

Answer

Answer: c

---

9. Amensalism is an association between two species where [NCERT Exemplar]
(a) one species is harmed and other is benefitted
(b) one species is harmed and other is unaffected
(c) one species is benefitted and other is unaffected
(d) both the species are harmed.

Answer

Answer: b

---

10. A population has more young individuals compared to the older individuals. What would be the status of the population after some years? ]NCERT Exemplar]
(a) It will decline
(b) It will stabilise
(c) It will increase
(d) It will first decline and then stabilise

Answer

Answer: c

---

11. Which of the following would necessarily decrease the density of a population in a given habitat? [NCERT Exemplar]
(a) Natality > mortality
(b) Immigration > emigration
(c) Mortality and emigration
(d) Natality and immigration

Answer

Answer: c

---

12. What parameters are used for tiger census in our country’s national parks and sanctuaries? [NCERT Exemplar]
(a) Pug marks only
(b) Pug marks and faecal pellets
(c) Faecal pellets only
(d) Actual head counts

Answer

Answer: b

---

13. The organisms which can tolerate and thrive in a wide range of temperature, are called _______ .

Answer/Explanation

Answer:
Explaination: Eury thermal

---

14. The salinity (measured in parts per thousand) in the sea is ______ .

Answer/Explanation

Answer:
Explaination: 30-35

---

15. _______ is any attribute of an organism (morphological, physiological and behavioural) that enables it to live and reproduce in the given area. 24 Match the terms in Column I with their

Answer/Explanation

Answer:
Explaination: Adaptation

---

16. _______ refers to the number of births during a given period of time that are added to the initial density.

Answer/Explanation

Answer:
Explaination: Natality

---

17. In a logistic growth curve, the final phase is an _______ .

Answer/Explanation

Answer:
Explaination: Asymptote

---

18. _______ fish breed only once in their life time.

Answer/Explanation

Answer:
Explaination: Pacific salmon

---

19. An orchid growing as an epiphyte on a mango tree, is an example of _______ .

Answer/Explanation

Answer:
Explaination: Commensalism

---

20. _______ is an important process as it facilitates energy transfer through various organisms.

Answer/Explanation

Answer:
Explaination: Predation

---

21. _______ showed that five closely related species of warblers living on the same were able to avoid competitions and co-exist.

Answer/Explanation

Answer:
Explaination: MacArthur

---

22. Zooplanktons enter, a state of suspended development under unfavourable conditions.

Answer/Explanation

Answer:
Explaination: Diapause

---

23. Match the terms in Column 1 with those in Column II.

Column I	Column II
A. Amensalism	1. The interspecific interaction, where both are equally benefitted.
B. Parasitism	2. The interspecific interaction, where one is benefitted and one is neutral.
C. Mutualism	3. The interspecific interaction, where one is harmed and the other is neutral.
D. Commen­salism	4. The interspecific interaction, where one is benefitted and one is harmed.
E. Competition

Answer/Explanation

Answer:
Explaination: A – 3, B – 4, C – 1, D – 2

---

24 Match the terms in Column I with their descriptions in Column II.

Column I	Column II
A. Home­ostasis	1. Animal which can tolerate a wide range of temperature.
B. Confor­mers	2. The number of births in a given population at a given time.
C. Natality	3. Per capita births in a given population.
D. Eury- thermal	4. A Maintenance of a relatively constant internal environment.
	5. Animals which change their body temperature according to the ambient temperature.

Answer/Explanation

Answer:
Explaination: A – 4, B – 5, C – 2, D – 1

---

25. Zooplanktons enter a state of suspended development, called diapause, under unfavourable conditions. [True/False]

Answer/Explanation

Answer:
Explaination: True.

---

26. The success of mammals is due to their ability to change their body temperature according to their surroundings. [True/False]

Answer/Explanation

Answer:
Explaination: True.

---

27. Small animals like shrews and humming birds are rarely found in polar regions. [True/False]

Answer/Explanation

Answer:
Explaination: True.

---

28. Organisms living in water bodies (lake, sea, river) do not face any water related problems. [True/False]

Answer/Explanation

Answer:
Explaination: False.

---

29. dSfdt=rN is the equation describing logistic growth. [True/False]

Answer/Explanation

Answer:
Explaination: False.

---

Directions (Q30 to Q32): Mark the odd one in each of the following groups.
30. Aestivation, Migration, Hibernation, Diapause.

Answer/Explanation

Answer:
Explaination: Migration.

---

31. Parasitism, Predation, Commensalism, Amensalism.

Answer/Explanation

Answer:
Explaination: Amensalism.

---

32. Ticks, Lice, Copepods, Tapeworm.

Answer/Explanation

Answer:
Explaination: Tapeworm.

---

33. Who is considered as the ‘Father of Ecology ’ in India?

Answer/Explanation

Answer:
Explaination: Ramdeo Misra.

---

34. What is ecology at the organismic level?

Answer/Explanation

Answer:
Explaination: Ecology at the organismic level is essentially physiological ecology, which tries to understand how different organisms are adapted to their environments in terms of not only survival but also reproduction.

---

35. What causes the annual variation in the intensity and duration of temperature?

Answer/Explanation

Answer:
Explaination:
– Rotation of earth around the Sim.
– Tilt of the earth on its axis.

---

36. Name the two factors that cause the formation of major biomes.

Answer/Explanation

Answer:
Explaination:
– Variation in the intensity and duration of temperature.
– Variation in precipitation.

---

37. What does the ecological niche of an organism represent?

Answer/Explanation

Answer:
Explaination: Ecological niche of an organism represents the range of conditions it can tolerate, the resources it utilises and its functional role in the ecosystem.

---

38. Why are mango trees unable to grow in temperate climate? [AI 2016C]

Answer/Explanation

Answer:
Explaination:
– The levels of thermal tolerance of species determine their geographical distribution, because temperature affects the physiological functions by affecting the kinetics of enzymes.
– Stenothermal organisms (like mango) can tolerate and survive only in a narrow range of temperature, say tropics.

---

39. Mention the effect of global warming on the geographical distribution of stenothermals like amphibians. [Foreign 2012]

Answer/Explanation

Answer:
Explaination: Stenothermal animals have tolerance to a narrow range of temperatures and hence their geographical distribution would be much affected.

---

40. Between amphibians and birds, which will be able to cope with global warming? Give reason. [HOTS]

Answer/Explanation

Answer:
Explaination: Birds will be able to cope with global warming; they are eurythermals and can tolerate a wide range of temperatures.

---

41. How do herbs and shrubs survive under the shadow of big canopied trees in forests?

Answer/Explanation

Answer:
Explaination: The herbs and shrubs growing in the forests are adapted to photosynthesise optimally under very low light conditions.

---

42. Name a ‘photoperiod’-dependent process, one each in plants and in animals. [Foreign 2013]

Answer/Explanation

Answer:
Explaination:
– Flowering in plants.
– Timing of foraging or migration in plants.

---

43. Mention any two activities of animals which get cues from diurnal and seasonal variations in light intensity. [Delhi 2011C]

Answer/Explanation

Answer:
Explaination:
(i) Timing their foraging.
(ii) Migratory activities.
(iii) Reproduction. (any two)

---

44. Why are green algae not likely to be found in the deepest strata of the ocean? [AI 2013] [HOTS]
Or
Why are green plants not found beyond a certain depth in the ocean? [Delhi 2011] [HOTS]
Or
Why are green algae not found at lower depths of a sea? [Delhi 2011C]

Answer/Explanation

Answer:
Explaination: Green algae or plants are not found beyond a certain depth, as light (not all colour components of visible spectrum) is not available.

---

45. What is the advantage of homeostasis to organisms that exhibit it?

Answer/Explanation

Answer:
Explaination: Homeostasis enhances the overall fitness of organisms because all biochemical reactions and physiological functions proceed with maximal efficiency.

---

46. Which feature of mammals, is the success rate of them, attributed to?

Answer/Explanation

Answer:
Explaination: Their ability to maintain a constant body temperature irrespective of the environmental temperature.

---

47. Why have many animals not evolved thermo¬regulation? [HOTS]

Answer/Explanation

Answer:
Explaination: Thermoregulation is an energy-expensive phenomenon; considering the cost and benefit, many animals have not evolved thermoregulation.

---

48. What are partial regulaters?

Answer/Explanation

Answer:
Explaination: Partial regulaters are those species which have the ability to regulate, but only over a limited range of environmental conditions, beyond which they simply conform.

---

49. What are osmoconformers?

Answer/Explanation

Answer:
Explaination: Osmoconformers are those organisms which regulate the osmolarity of their body fluids according to their surrounding medium.

---

50. What is migration?

Answer/Explanation

Answer:
Explaination: Migration refers to the movement of animals from the stressful habitat to a more hospitable area and return to the original place once the stressful period is over.

---

51. Name the National Park in India where migratory birds arrive in winter from Siberia.

Answer/Explanation

Answer:
Explaination: Keolado National Park, Bharatpur.

---

52. Mention how bears escape from stressful time in winter. [Delhi 2013C]

Answer/Explanation

Answer:
Explaination: Bears go into hibernation in winter.

---

53. How do snails escape from the stressful time in summer? [AI2013C]
Or
How do animals like fish and snails avoid summer-related unfavourable conditions? [Delhi 2010]

Answer/Explanation

Answer:
Explaination: Snails and fish go into aestivation in summer.

---

54. When and why do animals like frog/bear hibernate?

Answer/Explanation

Answer:
Explaination: If the unfavourable (stressful) conditions are for a short duration and if the animals are not able to migrate, they hibernate during extreme winter to avoid the stress by escaping in time.

---

55. When and why do animals like snails go into aestivation?

Answer/Explanation

Answer:
Explaination: When the snails are not able to migrate from the stressful conditions in the habitat, they undergo aestivation during hot summers to avoid stress by escaping in time.

---

56. Give an example of an organism that enters ‘diapause’ and why? [Delhi 2014]

Answer/Explanation

Answer:
Explaination:
– Zooplankton.
– It is to tide over the temporary unfavourable conditions in the habitat.

---

57. How do seed-bearing plants tide over dry and hot weather conditions? [AI 2013C]

Answer/Explanation

Answer:
Explaination: In seed-bearing plants, the seeds and other vegetative reproductive structures serve to tide over the unfavourable conditions; they germinate to form new plants under favourable conditions.

---

58. Define adaptation.

Answer/Explanation

Answer:
Explaination: Adaptation is defined as any morphological, physiological or behavioural attribute of an organism that enables it to survive and reproduce in its habitat.

---

59. How do spines help the cactus plants survive in the desert?

Answer/Explanation

Answer:
Explaination:
(i) Leaves are reduced to spines to check transpiration.
(ii) Spines keep away the browsing animals.

---

60. What is meant by Allen’s Rule?

Answer/Explanation

Answer:
Explaination: Allen’s rule refers to the reduction of heat loss in animals by having shorter ears and limbs.

---

61. Why is population ecology considered an important area of ecology?

Answer/Explanation

Answer:
Explaination: Population ecology is an important area of ecology, because it links ecology with population genetics and evolution; natural selection operates at the level of population.

---

62. If 8 individuals in a laboratory population of 80 fruit flies died in a week, then what would be the death rate of the population for the said period? [Delhi 2010]

Answer/Explanation

Answer:
Explaination: The death rate of fruit flies is 8/80, i.e. 100 per thousand or 10 per cent or 0.1 per individual.

---

63. In a pond, there were 20 Hydrilla plants. Through reproduction, 10 new Hydrilla plants were added in a year. Calculate the birth rate of the population. [Delhi 2010]

Answer/Explanation

Answer:
Explaination: The birth rate of Hydrilla is 10/20, i.e. 500 per thousand or 50 per cent or 0.5 per individual.

---

64. Define population density.

Answer/Explanation

Answer:
Explaination: Population density refers to the total number of individuals of a species present per unit area or volume at a given time.

---

65. Provide an instance where the population size of a species can be estimated indirectly, without actually counting them or seeing them. [Delhi 2016C]

Answer/Explanation

Answer:
Explaination: Tiger census is carried out by counting the pug marks or faecal pellets.

---

66. Define natality.

Answer/Explanation

Answer:
Explaination: Natality is defined as the number of births that are added to the initial density in a population during a given period of time.

---

67. Define mortality.

Answer/Explanation

Answer:
Explaination: Mortality refers to the number of deaths in the population during a given period.

---

68. What does nature’s carrying capacity for a species indicate? [Foreign 2016]

Answer/Explanation

Answer:
Explaination: It refers to the maximum number of individuals of a population that the given environment can sustain with its resources.

---

69. Name two organisms (one plant and one animal) which breed only once in their lifetime.

Answer/Explanation

Answer:
Explaination: Bamboo; Pacific Salmon Fish.

---

70. Why have life history variations evolved?

Answer/Explanation

Answer:
Explaination: Life history variations have evolved in organisms to maximise their reproductive fitness or Darwinian fitness in their natural habitats.

---

71. Mention any two reasons why plants depend on other organisms for their survival, even though they make their own organic food.

Answer/Explanation

Answer:
Explaination:
(i) Plants depend on animals (mainly insects) for pollination.
(ii) They also depend on animals for dispersal of seeds and/or fruits.
(iii) They depend on the soil microbes, which can carry out decomposition of organic matter and return the inorganic nutrients to the soil for absorption by plants. (any two)

---

72. Why are cattle and goats not browsing the Calotropis growing in the fields? [Foreign 2011]

Answer/Explanation

Answer:
Explaination: Calotropis plants produce highly toxic cardiac glycosides; hence, the cattle avoid browsing them.

---

73. Write one common feature among predation, parasitism and commensalism.

Answer/Explanation

Answer:
Explaination: In all these, the interacting species live closely together and one of the species is benefitted.

---

74. What term is given to the predators of plants.

Answer/Explanation

Answer:
Explaination: Herbivores.

---

75. What type of interaction is shown by a sparrow eating the seeds?

Answer/Explanation

Answer:
Explaination: Predation.

---

76. An exotic variety of prickly pear introduced into Australia turned out to be invasive. How was it brought under control? [Delhi 2013C]

Answer/Explanation

Answer:
Explaination: By introducing a cactus-feeding moth.

---

77. Why are predators ‘prudent’ in nature? [HOTS]

Answer/Explanation

Answer:
Explaination: Predators are prudent in nature because if a predator is too efficient and over-exploits its prey, then the prey might become extinct and following it, the predator will also become extinct.

---

78. Why do predators avoid eating monarch butterfly? How does the butterfly develop this protective feature? [Foreign 2010]

Answer/Explanation

Answer:
Explaination:
– The monarch butterfly is highly distasteful to the predators.
– It is due to a chemical present in its body; the butterfly acquires this chemical during its caterpillar stage, by feeding on a poisonous weed.

---

79. Write what the phytophagous insects feed on. [Delhi 2012]

Answer/Explanation

Answer:
Explaination: Phytophagous insects feed on the sap and other parts of the plants.

---

80. Why is the problem of predation in plants more severe than that in animals? [HOTS]

Answer/Explanation

Answer:
Explaination: Problem of predation is severe for plants because they cannot move away from their predators.

---

We hope the given Biology MCQs for Class 12 with Answers Chapter 13 Organisms and Populations will help you. If you have any query regarding CBSE Class 12 Biology Organisms and Populations MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 14 Ecosystem. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Ecosystem MCQs Pdf with Answers to know their preparation level.

Ecosystem Class 12 Biology MCQs Pdf

1. Which of the following represents the sedimentary type of nutrient cycle?
(a) Nitrogen cycle
(b) Carbon cycle
(c) Phosphorus cycle.
(d) Oxygen cycle

Answer

Answer: c

---

2. In a pond ecosystem, the food chain starts with
(a) Zooplanktons.
(b) Small insects
(c) Phytoplanktons
(d) Small fishes

Answer

Answer: c

---

3. The last stable community in succession that is in equilibrium with the environment, is called
(a) serai community
(b) pioneer community
(c) climax community
(d) all of these

Answer

Answer: c

---

4. Which of the following is a pioneer species in xerarch succession?
(a) Phytoplanktons
(b) Lichens
(c) Bryophytes
(d) Sedges

Answer

Answer: b

---

5. Which of the following statements is correct for secondary succession?
(a) It begins on a bare rock.
(b) It occurs on a deforested area.
(c) It follows primary succession.
(d) It is similar to primary succession, but has a relatively fast pace.

Answer

Answer: d

---

6. The sequence of communities of primary succession in water is [NCERT Exemplar]
(a) phytoplankton, sedges, free-floating hydrophytes, rooted hydrophytes, grasses and trees.
(b) phytoplankton, free-floating hydrophytes, rooted hydrophytes, sedges, grasses and trees.
(c) free-floating hydrophytes, sedges, phytoplankton, rooted hydrophytes, grasses and trees.
(d) phytoplankton, rooted submerged hydrophytes, floating hydrophytes, reed swamp, sedges, meadow and trees.

Answer

Answer: d

---

7. The reservoir for the gaseous type of biogeochemical cycle exists in [NCERT Exemplar]
(a) stratosphere
(b) atmosphere
(c) ionosphere
(d) lithosphere

Answer

Answer: b

---

8. The process of mineralisation by micro organisms helps in the release of [NCERT Exemplar]
(a) inorganic nutrients from humus
(b) both organic and inorganic nutrients from detritus
(c) organic nutrients from humus
(d) inorganic nutrients from detritus and formation of humus.

Answer

Answer: a

---

9. Which of the following ecosystems is most productive in terms of net primary production? [NCERT Exemplar]
(a) Deserts
(b) Tropical rain forests
(c) Oceans
(d) Estuaries

Answer

Answer: b

---

10. Approximately how much of the solar energy that falls on the leaves of a plant is converted to chemical energy by photosynthesis? [NCERT Exemplar]
(a) Less than 1%
(b) 2-10%
(c) 30%
(d) 50%

Answer

Answer: b

---

11. Vertical distributioon of different species occupying different levels in an ecosystem, is called _______ .

Answer/Explanation

Answer:
Explaination: Stratification.

---

12. The rate of production of biomass is termed as _______ .

Answer/Explanation

Answer:
Explaination: Productivity.

---

13. The degradation of humus by some microbes to release the inorganic nutrients, is called _______ .

Answer/Explanation

Answer:
Explaination: Mineralisation.

---

14. _______ of organisms is the beginning of the detritus food chain.

Answer/Explanation

Answer:
Explaination: Death.

---

15. _______ are the saprotrophs (heterotrophs) which meet their energy requirements by degrading the detritus.

Answer/Explanation

Answer:
Explaination: Decomposers.

---

16. The amount of energy _______ at successive trophic levels.

Answer/Explanation

Answer:
Explaination: Decreases.

---

17. The _______ is measured as biomass or number per unit area.

Answer/Explanation

Answer:
Explaination: Standing crop.

---

18. The pyramid of number in a grassland ecosystem is .

Answer/Explanation

Answer:
Explaination: Upright.

---

19. are the pioneer species in the primary succession on a rock.

Answer/Explanation

Answer:
Explaination: Lichens.

---

20. The technical term given to nutrient cycles is cycles.

Answer/Explanation

Answer:
Explaination: Biogeochemical.

---

21. Match the items in Column I with those in Column II.

Column I	Column II
A. Standing crop	1. The amount of mineral nutrients in the soil at a given time
B. Standing state	2. Sedementary cycle
C. Climax community	3. Herbivores and carnivores
D. Primary producers	4. In near equilibrium with the environment
E. Phosphorus cycle	5. Mass of living matter in a trophic level at a given time
F. Secondary producers	6. Phytoplanktons

Answer/Explanation

Answer:
Explaination: A – 5, B – 1, C – 4, D – 6, E – 2, F – 3

---

22. Match the items in Column I with those in Column II.

Column I	Column II
A. Pyramid of  energy	1. Phytoplanktons
B. Pyramid of biomass	2. Mesic forest
C. Climax community	3. Upright/inverted
D. Hydrarch succession	4. Always upright
	5. Pioneer species

Answer/Explanation

Answer:
Explaination: A – 4, B – 3, C – 2, D – 1

---

23. Natural or man-made distribances during succession, can convert a particular serai stage to an earlier stage. [True/False]

Answer/Explanation

Answer:
Explaination: True.

---

24. The pioneer species always remain in equilibrium with the environment and do not change easily. [True/False]

Answer/Explanation

Answer:
Explaination: False.

---

25. The function of reservoir of any nutrient cycle is to store as much matter as possible. [True/False]

Answer/Explanation

Answer:
Explaination: False.

---

26. In a hydrarch succession, the marsh-meadow stage is preceded by the scrub stage. [True/False]

Answer/Explanation

Answer:
Explaination: False.

---

27. In an ecological pyramid, the amount of energy available at the lower trophic level is always more than that at a higher trophic level. [True/False]

Answer/Explanation

Answer:
Explaination: True.

---

Directions (Q28 and Q29): Mark the odd one in each of the following groups.
28. Phytoplanktons, Zooplanktons, Reed-swamp stage, Lichens.

Answer/Explanation

Answer:
Explaination: Lichens.

---

29. Fragmentation, Stratification, Leaching, Catabolism.

Answer/Explanation

Answer:
Explaination: Stratification.

---

30. What is an ecosystem?

Answer/Explanation

Answer:
Explaination: An ecosystem is a functional unit of nature, where biotic components (living organisms) interact among themselves and also with the abiotic environmental or physical factors.

---

31. What is meant by species composition in an ecosystem?

Answer/Explanation

Answer:
Explaination: Species composition refers to all the plant, animal and microbial species present in a given ecosystem.

---

32. What is ‘stratification’ in an ecosystem?

Answer/Explanation

Answer:
Explaination: ‘Stratification’ in an ecosystem refers to the vertical distribution of different species occupying different levels.

---

33. How is ‘ stratification’ represented in a forest ecosystem? [Delhi 2014]

Answer/Explanation

Answer:
Explaination: In a forest, the trees occupy the upper/ topmost vertical strata, the shrubs, the second and herbs, the bottom layers.

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34. How is primary productivity in an ecosystem determined? [AI2012C]

Answer/Explanation

Answer:
Explaination: Primary productivity is determined as the amount of biomass or organic matter produced per unit area over a time period by the plants during photosynthesis.

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35. GPP – R = NPP
What does ‘R’ represent in the given equation for productivity in an ecosystem? [Delhi 2014C]

Answer/Explanation

Answer:
Explaination: R represents the respiratory losses.

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36. What is net primary productivity of an ecosystem? [Foreign 2015]

Answer/Explanation

Answer:
Explaination: Net primary productivity of an ecosystem refers to the biomass available in the producers for consumption by heterotrophs, i.e., herbivores and decomposers.

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37. Write the equation that helps in deriving the net primary productivity of an ecosystem. [Delhi 2013]
Or
How is the net primary productivity of an ecosystem derived? [AI 2012C]

Answer/Explanation

Answer:
Explaination: Gross primary productivity (GPP) – Respiratory loss (R) = Net primary productivity (NPP); it is the amount of energy/biomass available in the producers for consumption by herbivores.

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38. How is net primary productivity different from gross primary productivity?[AI2012C]
Or
Write a difference between net primary productivity and gross productivity. [AI 2011]

Answer/Explanation

Answer:
Explaination:
Net primary productivity refers to the , biomass/organic matter available at the 1 producer level to the primary consumers,
i.e. GPP – Respiratory losses.
Gross primary productivity is the rate of production of biomass/organic matter by producers during photosynthesis.

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39. What is the approximate value of net primary productivity of the biosphere?

Answer/Explanation

Answer:
Explaination: 170 billion tons of (dry weight) organic matter.

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40. How much of productivity is contributed by oceans?

Answer/Explanation

Answer:
Explaination: Oceans contribute about 55 billion tons organic matter.

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41. Why is the assimilation of energy at the herbivore level, called secondary productivity?

Answer/Explanation

Answer:
Explaination: Herbivores are the primary consumers; the rate of assimilation or formation of new biomass at the consumer level is secondary productivity.

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42. All the primary productivity is not available to a herbivore. Give one reason. [HOTS]

Answer/Explanation

Answer:
Explaination: A considerable amount of gross primary productivity is used by the plants in respiration; so not all primary productivity is available for consumers.

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43. Name the two climatic factors that regulate decomposition.

Answer/Explanation

Answer:
Explaination: Temperature and soil moisture are the two climatic factors that regulate decomposition.

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44. Why is an earthworm called a detritivore? [Foreign 2012]

Answer/Explanation

Answer:
Explaination: Earthworms ingest and breakdown the detritus into smaller particles; hence they are called detritivores.

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45. What is meant by PAR?

Answer/Explanation

Answer:
Explaination: The part of the solar radiation which can be absorbed and used by the plants for photosynthesis, is called photosynthetically active radiation (PAR).

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46. What are primary carnivores?

Answer/Explanation

Answer:
Explaination: Primary carnivores are the secondary consumers, which depend on the herbivores (primary consumers) for their food needs.

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47. What is a detritus food chain made up of? How do they meet their energy and nutritional requirements? [AI 2013]

Answer/Explanation

Answer:
Explaination:
– It is made up of decomposers, i.e. some bacteria and some fungi.
– They meet their energy and nutrient requirements by degrading the dead organic matter or detritus.

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48. Name two omnivores that occupy positions in both grazing food chain as well as detritus food chain.

Answer/Explanation

Answer:
Explaination: Cockroaches and crows.

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49. Write the basis on which an organism occupies a space in its community/natural surroundings. [Foreign 2010]

Answer/Explanation

Answer:
Explaination: Their feeding relationship with other organisms.

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50. Mr Galgotia eats curd/yoghurt. In this case, which trophic level will he occupy? [CBSE Sample Paper 2010; HOTS]

Answer/Explanation

Answer:
Explaination: He occupies third tropic level, i.e., he is a secondary consumer.

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51. ‘Man can be primary as well as a secondary consumer.’ Justify this statement. [Foreign 2015]

Answer/Explanation

Answer:
Explaination:
– When man eats plant food, he is primary consumer.
– When he eats meat (animal food), he is a secondary consumer.

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52. State what ‘standing crop’ of a trophic level represents. [AI 2013]

Answer/Explanation

Answer:
Explaination: Standing crop of a trophic level represents the amount of living matter (biomass) present at a trophic level at a given time.

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53. List any two ways of measuring the standing crop of a trophic level. [Foreign 2010]

Answer/Explanation

Answer:
Explaination:
Standing crop is measured as
(i) biomass, i.e. mass of living organisms in an unit area
(ii) number of organisms in an unit area.

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54. How are biomass and standing crop related to each other? [CBSE Sample Paper 2013, 2014]

Answer/Explanation

Answer:
Explaination:
– Biomass is the mass of living organisms or organic matter.
– Standing crop is measured in terms of biomass.

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55. Why is measurement of biomass in terms of dry weight more accurate than fresh weight? [HOTS]

Answer/Explanation

Answer:
Explaination: Measurement of biomass in terms of dry weight is more accurate because it avoids variations in weights due to seasonal moisture differences.

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56. Define ecological succession.

Answer/Explanation

Answer:
Explaination: Ecological succession is a community controlled phenomenon, in which the structure and composition of communities change in an orderly and sequential manner, leading ultimately to the establishment of a climax community.

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57. What is a sere?

Answer/Explanation

Answer:
Explaination: The entire sequence of communities, that successively change in a given area resulting in a climax community, is called a sere.

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58. Define climax community.

Answer/Explanation

Answer:
Explaination: The community established at the terminal stage of succession, is called climax community.

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59. Mention the role of pioneer species in primary succession on rocks. [Foreign 2012]

Answer/Explanation

Answer:
Explaination: Lichens are the pioneer species in the succession on rocks; they secrete acids to dissolve the rock and help in weathering and soil formation and pave way to bryophytes.

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60. In the North East region of India, during the process of jhum cultivation, forests are cleared by burning and left for regrowth after a year of cultivation. How would you explain the regrowth of forest in ecological terms? [HOTS]

Answer/Explanation

Answer:
Explaination: It is secondary succession.

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61. Differentiate between standing state and standing crop in an ecosystem. [Foreign 2010]

Answer/Explanation

Answer:
Explaination:
Differences:

Standing State	Standing Crop
– Standing state refers to the amount of nutrients such as nitrogen, phosphorus, calcium, etc. present in the soil of an ecosystem at a given time.	– Standing crop refers to the amount of biomass or organic matter available at a given trophic level/ecosystem at a given time.
– It is in the abiotic components.	– It is in the biotic components.

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62. Name the two forms of reservoir of carbon, that regulate the ecosystem carbon cycle.

Answer/Explanation

Answer:
Explaination:
(i) Dissolved carbon in oceans.
(ii) Carbon in fossil fuels.

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63. How much of carbon is
(a) fixed in the biosphere through photosynthesis annually?
(b) dissolved in the ocean?

Answer/Explanation

Answer:
Explaination:
(a) 4 × 10¹³ kg of carbon is fixed annually.
(b) 71% of carbon is dissolved in the ocean.

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64. Name the natural reservoir of phosphorus and the form in which it is present.

Answer/Explanation

Answer:
Explaination:
– Rocks are the natural reservoir of phosphorus.
– It is present in the form of phosphates.

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65. Who put a price tag for the ecosystem services? What is its value?

Answer/Explanation

Answer:
Explaination:
– Robert Constanza et al have tried to put a price tag. , – It’s estimated to be about 33 trillion US dollars.

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