ISC Class 12 Competency Based Questions (CBQ) Environmental Science

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PREFACE

With a growing emphasis on competency-based education globally, the educational landscape
in India has also steered towards high-quality learning experiences that allow learners to
incorporate critical thinking and problem-solving approaches. This approach goes beyond rote
memorisation and focuses on developing the skills and knowledge that students need to apply
in their real-world scenarios.
The Council for the Indian School Certificate Examinations (CISCE), as a national-level
progressive examination board, has taken several steps to infuse competency-based education
in CISCE schools through teacher capacity-building on item development for competency-
based assessments and the incorporation of competency-focused questions at the ICSE and ISC
levels from the examination year 2024.
To further facilitate the adoption of competency-based assessment practices in schools and to
support teachers and students towards the preparation for attempting higher-order thinking
questions in future board examinations, Item Banks of Competency-Focused Practice
Questions for selected subjects at the ICSE and ISC levels have been developed. This Item
Bank consists of a rich variety of questions, both objective and subjective in categories, aimed
at enhancing the subject-specific critical and analytical thinking skills of the students.
In this Item Bank, each question is accompanied by the topic and cognitive learning domain/s
that it intends to capture. The cognitive domains reflected in these questions include
understanding, analysis, application, evaluation and creativity, along with some questions of
the higher-order recall domain. The Answer Key at the end presents the possible answers to a
given question, but it is neither limiting nor exhaustive.
These practice questions are also meant to serve as teacher resources for classroom assignments
and as samplers to develop their own repository of competency-focused questions. Apart from
offering a good practice of higher-order thinking skills, engaging with these questions would
allow students to gauge their own subject competencies and use these assessments for learning
to develop individual learning pathways.
During the development of this Item Bank, a large pool of questions was prepared by a team
of experienced CISCE teachers. The questions that were finalised by the internal and external
reviewers as being higher-order competency-focused questions have been collated in this item
bank.
I acknowledge and appreciate all the ICSE and the ISC subject matter experts who have
contributed to the development and review of these high-quality competency-focused questions
for CISCE students.
We are hopeful that teachers and students will utilise these questions to support their
teaching-learning processes.

September 2024 Dr. Joseph Emmanuel
Chief Executive & Secretary
CISCE

Environmental Science ISC-Class XII

Table of Contents

S.No. Type of Questions Page Nos.

I. Multiple Choice Questions (MCQs) 1-8

II. Assertion-Reason Questions 9-14

III. Very Short Answer Questions 15-16

IV. Short Answer Questions 17

V. Long Answer Questions 18-22

VI. Very Long Answer Questions 23-24

Answer Key 25-32

ISC Competency-Focused Practice Questions

Environmental Science ISC-Class XII

COMPETENCY-FOCUSED PRACTICE QUESTIONS

ISC-CLASS XII

Environmental Science

I: Multiple Choice Questions (1 Mark Each)

S.No. Questions

1. [Third World Development]
Activated biomass is used for treating which of the following waste/gases?
(a) Toxic gases.
(b) Wastewater
(c) Nuclear waste
(d) Solid waste
(Understanding)

2. [International Relations and the Environment]
Which of the following is NOT an ozone-depleting substance?
(a) Chlorofluorocarbons
(b) Methyl Chloroform
(c) Halons
(d) Steel

(Recall)

3. [Monitoring Pollution]
Which type of pollution is indicated by a high Biochemical Oxygen Demand (BOD) level?
(a) Air Pollution
(b) Water Pollution
(c) Thermal Pollution
(d) Radioactive Pollution

(Understanding)

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Environmental Science ISC-Class XII

S.No. Questions

4. [Environment and Natural Resource Economics]
Which scenario BEST illustrates the limitations of non-renewable resources?
(a) A factory extracts minerals from a mine which is used as raw materials in its manufacturing
process.
(b) An oil field's output decreases significantly after years of extensive drilling, leading to an
energy crisis.
(c) A community relies on solar panels for their primary energy source, reducing their carbon
footprint.
(d) A government invests heavily in the research and development of wind energy technology.
(Understanding)

5. [Sustainable Agriculture]
Study the image of macro-irrigation carefully and answer the question that follows.

Which of the following is NOT an advantage of the above method of irrigation?
P. Ensures constant water supply.
Q. Productive agricultural land or forest land can get submerged.
R. It can cause earthquakes due to the high pressure of stored water.
S. Leads to the evaporation of water.
Choose the MOST appropriate option based on the above statements.
(a) Only P
(b) R and S
(c) P and S
(d) Q, R, and S

(Understanding)

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S.No. Questions

6. [Third World Development]
The following graph represents data from a study based on push and pull factors that are
driving rural-urban migration in Uttarakhand, India.

Source: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0214511
Examine the above graph and choose the MOST appropriate inference from the options given
below.
(a) Both push and pull factors were equally responsible for migration.
(b) Opportunities for progress in Uttarakhand cities are absent.
(c) People have found employment opportunities in the villages adequately.
(d) The village economy is in very bad shape and lacks measures for progress.
(Analysis)

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S.No. Questions

7. [Monitoring Pollution]
The image below illustrates a critical global environmental problem alongside its underlying
causes.
Study the picture carefully and choose the CORRECT option from the options given below.

Source: https://easy-peasy.ai/ai-image-generator/images/climate-change-sketch-melting-
glacier-industrial-smokestacks
(a) Problem -ozone depletion, cause- deforestation, industrialisation.
(b) Problem- eutrophication, cause- nuclear radiation and deforestation.
(c) Problem- global warming – cause- deforestation and industrialisation.
(d) Problem – urbanisation, cause- migration, developmental activities.
(Analysis)

8. [Third World Development]
Arrange the steps of Decentralized Wastewater Treatment System (DEWATS) treatment in a
logical sequence.

P. Organic matter is degraded by active biomass attached to the filter.
Q. Removal of remaining suspended solids and BOD.
R. Small particles are brought together to form larger particles and settle down.
S. Planted gravel filter filters the water and removes the odour.

The CORRECT sequence of these steps is:

(a) P- Q- R- S
(b) S -R- Q -P
(c) R- P- Q- S
(d) P -R- S- Q
(Understanding)

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S.No. Questions

9. [Population and Conservation Ecology]
Choose the least appropriate trait depicted by ‘r’ strategists.
(a) High population growth rate.
(b) Short life expectancy.
(c) The small size of organism.
(d) Attains late sexual maturity.
(Recall)

10. [Monitoring Pollution]
Read the following statements given below:
I. Soil respiration is one of the measures of biological activity.
II. The optimum potential of hydrogen (pH) value of the soil ranges from 3.5 to 5.5.
III. Low turbidity in a water sample is an indication of bacterial contamination.
IV. Sandy soils have poor water retention as compared to clay soils.

Which of the above statements are true?
(a) I and IV
(b) II and IV
(c) I and III
(d) I and II
(Understanding)

11. [Human Beings and Nature]
The following statements highlight the basic principles of Sustainable development. Identify
and choose the INCORRECT statement from the given options:
(a) The principle of integration ensures coordination of regional, and national activities.
(b) The principle of utilising local resources promotes the utilisation of native resources for
the benefit of local inhabitants.
(c) The principle of public participation denotes that industries polluting the environment must
be penalised.
(d) The principle of sustainable management of resources promotes the conservation of
biodiversity. (Application)

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S.No. Questions

12. [Monitoring Pollution]
Identify the correct parameter in the picture given below which is used to indicate water
pollution.

(a) Chemical oxygen demand
(b) Electrical conductivity
(c) Turbidity
(d) Biological oxygen demand
(Application)

13. [Population and Conservation Ecology]
The table below shows the population dynamics of a village in a particular year. Use the data
in the table below to calculate the population size of this village at the year-end.
Population at the beginning of the year 10,000

Total live Births in that year –(B) 30

Recorded deaths in that year – (D) 20

Recorded Immigrants in that year (I) 100

Recorded Emigrants in that year (E) 50

Final population at the year-end ‘X’ [to be calculated]

Choose the correct answer for ‘X’ from the options given below.
(a) 10,060
(b) 10,000
(c) 10,500
(d) 10,200
(Application)

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S.No. Questions

14. [Sustainable Agriculture]
Select the phrase which is NOT a key component of the green revolution.
(a) Use of heavy agricultural equipment.
(b) Use of fertilisers and pesticides.
(c) Use of high-yielding seed varieties.
(d) Use of integrated pest management.
(Understanding)

15. [Monitoring Pollution]
Study the picture below of the Non -Dispersive Infrared [NDIR] device and choose the correct
statement from the options given below.

(a) It is a manual technique to monitor particulate pollutants.
(b) It is an instrumental technique to monitor gaseous pollutants.
(c) It is a manual technique to monitor gaseous pollutants.
(d) It is an instrumental technique to monitor particulate pollutants.
(Analysis)

16. [Population and Conservation Ecology]
An eye surgeon wants to preserve the cornea of an eye donated by another patient. It is
preserved in liquid nitrogen by maintaining a temperature of -196 degrees Celsius.

Name the term that defines the above process being used.

(a) Tissue Culture
(b) Cryopreservation
(c) Gene Bank
(d) Captive Breeding (Recall)

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S.No. Questions

17. [International Relations and the Environment]
Which of the following options represents an outcome of the ban on toxic waste and its import
to African countries?
(a) Basel Convention
(b) General Agreement on Tariffs and Trade (GATT)
(c) Montreal Protocol
(d) Bamako Convention (Recall)

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II. Assertion-Reason Questions (1 Mark Each)

The questions in this section have two statements marked Assertion and Reason. Read both the
statements carefully and choose the correct option.

S.No. Questions

18. [International Relations and the Environment]
Assertion (A): Deforestation in Amazonia is primarily due to agricultural expansion.
Reason (R): The demand for timber & cattle ranching has led to the widespread clearing
of Amazon rainforest.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, and R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

19. [International Relations and the Environment]
Assertion (A): Chapman’s cycle describes the natural process by which ozone is created &
destroyed in the Earth’s stratosphere.
Reason (R): Ultraviolet (UV) radiation from the sun splits oxygen molecules into
individual oxygen atoms, which then react with the other oxygen molecules to form ozone.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) (A) is true, but (R) is false.
(d) (A) is false, but (R) is true.
(Understanding)
20. [Environmental and Natural Resource Economics]
Assertion (A): Environmental economics indicates the economic impact of environmental
policies and the allocation of resources to address environmental issues.
Reason (R): It incorporates principles from both economics and ecology to analyse the
relationship between anthropogenic activities & the environment.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

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S.No. Questions

21. [Sustainable Agriculture]
Assertion (A): Anti-oxidants help preserve food.
Reason (R): They protect food from going rancid.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

22. [Sustainable Agriculture]
Assertion (A): Dams are easy to build and cost-effective.
Reason (R): Dam water is used to irrigate large tracts of land.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

23. [Sustainable Agriculture]
Assertion (A): Eris were important traditional water harvesting systems in Tamil Nadu.
Reason (R): Eris were built in the courtyards of households to store rainwater.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

24. [Third World Development]
Assertion (A): Cuba’s main focus in sustainable development is its excellent public
transport system.
Reason (R): A good public transport system helps in cutting down greenhouse gas
emissions.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

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S.No. Questions

25. [Third World Development]
Assertion (A): Rainwater harvesting is essential to conserve water in urban areas through
rooftop collection and storage.
Reason (R): Urban areas are highly concretised and there is not enough exposed soil for
water to percolate.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Recall)

26. [Sustainable Agriculture]
Assertion (A): Support to marginal farmers helps in increasing food security.
Reason (R): The growing trend in agricultural sector in developing countries is that
multinational companies are investing in agriculture.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true (Understanding)

27. [Sustainable Agriculture]
Assertion (A): Sugar or salt is used commonly to preserve food during processing.
Reason (R): Sugar and salt provide a good medium for bacteria to grow.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

28. [Sustainable Agriculture]
Assertion (A): During British rule in India, the government invested a lot of money for the
agricultural sector.
Reason (R): British rule in India saw the advent of commercialisation of agriculture.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
(Understanding)

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S.No. Questions

29. [International Relations and the Environment]]
Assertion (A): Increased production of greenhouse gases leads to higher surface
temperatures of the earth, thus contributing to climate change.
Reason (R): Chlorofluorocarbons (CFC’S) deplete the ozone layer.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

30. [Third World Development]
Assertion (A): The village as the self-sufficient unit of development was Gandhi’s dream.
Reason (R): Village development can be achieved through the use of heavy machinery and
producing goods for export.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

31. [Third World Development]
Assertion (A): Tertiary treatment in the process of DEWATS includes passing the waste
water through planted gravel.
Reason (R): Gravel and plant roots help by adding oxygen for better treatment of the
wastewater.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

32. [Monitoring Pollution]
Assertion (A): Higher Nitrogen mineralisation is considered an important biological
indicator of soil health.
Reason (R): Testing of soil will give an accurate reading of soil health.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

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S.No. Questions

33. [Monitoring Pollution]
Assertion (A): “Carbon trading” is an approach to reduce the total global emissions over
a period.
Reason (R): This limit ensures that the environmental goals are met, while also being
flexible for individual emissions.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

34. [Monitoring Pollution]
Assertion (A): Chemiluminescence is a diagnostic technique to detect water pollution.
Reason (R): Chemiluminescence is a method used to detect the presence of oxides of
nitrogen in air samples.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

35. [Human Beings and Nature]
Assertion (A): Wendell Berry is a poet, farmer writer and an eminent ecological thinker.
Reason (R): Wendell Berry wrote several books on the adverse effects of nuclear testing
on the environment.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Recall)

36. [Population and Conservation Ecology]
Assertion (A): Frogs and butterflies are examples of the Type III survivorship curve.
Reason (R): The mortality rate of such organisms is high in their later stages of life.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Recall)

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S.No. Questions

37. [Population and Conservation Ecology]
Assertion (A): Conflict between governments and local villagers is seen as a limitation in
the process of social forestry.
Reason (R): Forest departments may have prohibitions on the cutting of a particular tree
species or may limit the grazing of cattle.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

38. [Population and Conservation Ecology]
Assertion (A): The objective of in-situ conservation is re-introduction and support to
wildlife populations outside their habitat.
Reason (R): It is often claimed that zoos perform valuable conservation work by captive
breeding of endangered species.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

39. [Population and Conservation Ecology]
Assertion (A): Conservation of forests is vital for watershed management.
Reason (R): Forests act as buffers to save us from global warming.

(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

40. [Population and Conservation Ecology]
Assertion (A): An urn-shaped population pyramid is a boon for the economy of a country.
Reason (R): A country with a greying population can face a shortage of labour resources,
thus leading to an economic recession.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true. (Understanding)

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III. Very Short Answer Questions (1 Mark Each)

S.No. Questions

Fill in the Blank from Q.NO. 41 to Q.No. 44.

41. [Third World Development]
The special buses called ________ were running in Bogota in fixed lanes to avoid traffic
congestion. (Understanding)

42. [Third World Development]
Anaerobic treatment in fixed bed reactors, baffled upstream reactors or anaerobic filters are
the ___________ treatment stage in DEWATS. (Understanding)

43. [Population and Conservation Ecology]
The practice of forestry on government wastelands is called__________.
(Recall)

44. [Population and Conservation Ecology]
The _____________growth curve shows ever-increasing population growth with few
resource limitations. (Understanding)

State True or False from Q.No. 45. to Q.No. 48. This is from the Unit Monitoring Pollution.

45. A leak in the sewage pipeline present underground will decrease the electrical conductivity
of water. (Analysis)

46. A high level of dissolved oxygen (DO) is an indicator of good-quality of water.
(Understanding)

47. A water sample with a pH of 5 is good for drinking. (Understanding)

48. A high turbidity value indicates the good quality of the water sample.
(Understanding)

Name the following using one-word answers from Q. No. 49 to Q.No. 53. (Recall)

49. [Internal Relations and the Environment]
A foreign aid where the country decides how the aid will be utilised.

50. [Internal Relations and the Environment]
An exclusive right is given to an inventor to ensure that no other person is making, using or
selling the invention.

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S.No. Questions

51. [Environmental and Natural Resource Economics]
A strategy aimed at manufacturers in which the manufacturers are responsible for the proper
disposal of the products they sell so that to reduce the waste and promote environmental
awareness.

52. [Third World Development]
The sewage system which helps in addressing human excreta using no water or very little
water.

53. [Population and Conservation Ecology]
The type of life strategists which show late maturity and long-life expectancy.

For Q. No. 54 to Q.No. 58, identify the Ecological Thinkers. All these questions are from the
Unit Human Beings and Nature. (Recall)

54. Name the author of the book, ‘Silent Spring’.

55. The ecological thinker who taught at the University of California developed a new discipline
based on studies of nature and culture.

56. The ecological thinker who contributed to the adoption of the Nuclear Test Ban Treaty of
1963.

57. Who championed for the ethical value of ‘Stewardship of Land?’

58. Who founded the environmental group ‘Earth First’?

From Q. No. 59 to Q.No. 63, write Expanded Forms. (Recall)

59. (Population and Conservation Ecology)
MAB

60. (Population and Conservation Ecology)
FPC

61. (Monitoring Pollution)
NAAQS

62. (Monitoring Pollution)
NDIR

63. (Sustainable Agriculture)
AFSI

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IV: Short Answer Questions (2 Marks Each)

S.No. Questions

64. [Human Beings and Nature]
Francoise D’Eaubonne was the pioneer of a unique ecology movement in the early
1980’s. Name the movement that she was associated with. State the main principle behind
this social movement. (Recall)

65. [Monitoring Pollution]
Study the table given below and answer the questions that follow.

Two water samples were tested in a laboratory for estimating their BOD values. The
results showed that Sample ‘A’ has a BOD value of 8.5mg/litre and Sample ‘B’ has a
BOD value of 4.2 mg/litre. Based on the available results, use the above-given chart to
answer the questions below.
(a) Write an inference of both the water samples in terms of their water quality.
(b) State the significance of dissolved oxygen in a water body.
(Evaluation)

66. [Sustainable Agriculture]

(a) Identify the type of irrigation system.
(b) Give one each advantage and disadvantage of the irrigation system identified in the
above picture. (Recall)

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V. Long Answer Questions (4 Marks Each)

S.No. Questions
67. [Environmental and Natural Resource Economics]
Compare and contrast the strengths of Gross National Product (GNP) in relation to Gross
Domestic Product (GDP), emphasising how each metric offers unique insights into a nation's
economic activity. (Application)

68. [Environmental and Natural Resource Economics]
Dichlorodiphenyltrichloroethane (DDT) concentration in the water of a lake that supplies
potable water to the nearby villages was found to be 0.003 ppm. It was reported that native
birds like kingfisher near the lake were found to have 2 ppm of DDT in their bodies.
With reference to the context, answer the questions that follow.
(a) State the reasons behind the increased concentration of DDT in these birds.
(b) Name the phenomenon and explain it briefly.
(Analysis)

69. [Environmental and Natural Resource Economics]
The government’s decision of compulsory vaccination drive against COVID-19 is a good
example of a certain kind of ecologically beneficial expenditure.
(a) Identify the type of expenditure is being referred above.
(b) Cite three more recent examples of such kind of expenditure. (Application)

70. [Sustainable Agriculture]
Look at the two crops shown in the picture below:

Figure A Figure B
(a) Identify two crops.
(b) Give any two aspects of their significance in agriculture in India before independence?
(Analysis)

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S.No. Questions
71. [Sustainable Agriculture]
Read the passage given below.
“Tenancy Reforms: What Succeeded and What Failed?
In the earlier phases of land reforms, the measures were divided into four groups:
liberative, distributive, organizational, and developmental. It was aimed at the liberation of
the actual tillers of the land from the yoke of the landlord. This was to be achieved by
conferring the land title or occupancy rights of the tenant.
Source(edited)- [Current land policy issues in India- R.S. Deshpande] [Professor and Head,
Agricultural Development and Rural Transformation Unit, Institute for Social and
Economic Change, Bangalore, India]
(a) What is the law/legislation being mentioned in the above passage? (Recall)
(b) Cite any three reasons which highlight the significance of this Act. (Analysis)

72. [Sustainable Agriculture]
Read the following passage and answer the questions that follow.

Source: Times of India Website, December 21, 2023
(a) Name and define the problem mentioned in the above passage.
(b) Name any two quality marks used in India to check the food grade and its quality.
(c) Name the substances which are illegally used to degrade the quality of honey and pepper.
(Recall)

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S.No. Questions
73. [Sustainable Agriculture]
Read the following passage and answer the questions that follow.

(a) Why is it important to classify waste as organic and inorganic waste? Give any three
reasons. (Evaluate)
(b) Name the process which can change organic waste to useful material. (Recall)

74. [Third World Development]
Read the statement given below and answer the questions in light of the statement
given.
“In today’s flush-based urban sanitation systems, toilets are connected to both the
centralised water and wastewater infrastructures.”
(a) What is the impact of this system?
(b) Give one alternative to reduce the environmental impacts of flush-based toilet sanitation
systems that will be tried out. Explain. (Understanding)

75. [Population and Conservation Ecology]
Differentiate between Biosphere reserves and Sanctuaries.

(Understanding)

76. [Population and Conservation Ecology]
As a conservationist, prepare a report on the declining sparrow population in metropolitan
cities. As a part of the report, state four important reasons for the potential threats for the
survival of this species. (Understanding)

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Environmental Science ISC-Class XII

S.No. Questions
77. [Population and Conservation Ecology]
Study the picture given below and answer the questions that follow.

(a) Identify the phenomenon depicted in the above graphical representation of a population.
(Analysis)
(b) Define the answer in part (a). (Recall)
(c) Differentiate between the features seen in stage 1 and stage 4 of the above graph.
(Analysis)

78. [Monitoring Pollution]
The Central Pollution Control Board is responsible for maintaining good air quality.
Mention four functions of this board which help in improving the quality of air in our
country. (Recall)

79. [Human Beings and Nature]
Look at the picture below. Read the passage below. Answer the questions that follow.
“When you burn wood, it does not disappear, it turns into smoke, which rises into the air
and forms ash, which falls back down to the earth”.

(a) State the law of ecology associated with the above phenomenon and describe it.
(b) The third law of ecology states “Nature knows best.” Justify this law by giving a relevant
example.
(Analysis)

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Environmental Science ISC-Class XII

S.No. Questions
80. [International Relations and the Environment]

Observe the picture given below & answer the questions that follow.

(a) Identify the product which is being traded in the above picture. (Analysis)
(b) State the reason behind the Convention on International Trade in Endangered Species of
Wild Fauna and Flora (CITES) banning the trade mentioned above. (Application)
(c) State any two effects of this ban. (Recall)

81. [Sustainable Agriculture]
There was a need for a green revolution when India went in for it in the early years after
independence. List any four points on how agriculture can be made sustainable in India.
(Evaluate)

82. [Population and Conservation Ecology]
The graph given below depicts the growth of a population. Study the graph and answer
the questions that follow.

(a) Name the phases ‘A and ‘C’ in the above graph. (Application)
(b) What does resource limitation in the graph denote? (Understanding)
(c) Name any two factors which regulate population size. (Recall)

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Environmental Science ISC-Class XII

VI: Very Long Answer Questions (7 Marks Each)

S.No. Questions

83. [Third World Development]
His early Satyagraha in Champaran and Kheda (1917 and 1918) also opened his eyes to the
economic exploitation of the villagers by the British. Since eighty percent of the population
of India lived in villages, for Gandhi, the economic and social revival of the seven lakh villages
was a top priority. In his own words- "To serve our villages is to establish Swaraj. Everything
else is but an idle dream". Many years later, in 1933, on his nation-wide tour in which he
covered 12,500 miles in nine months, penetrating some of the remotest villages on foot, he
saw the plight of the deprived sections of society, and he brought in even more reforms into
his concept of Gram Swaraj.”
(a) What are the basic principles of the village policy of Gandhi as highlighted in the above
passage? Explain any three principles. (Recall)
(b) Why did Gandhiji focus on intermediate technology for villages and not on industrial
development as an economic answer to the issue of development for India?
(Analysis)
(c) Compare and contrast the modern developmental paradigm with Gandhi’s vision for
development for India. (Analysis)

84. [Population and Conservation Ecology]
Study the image given below and answer the questions that follow.

(a) Identify and define the type of social forestry depicted in the above picture.
(b) How is social forestry different from Joint Forest management?
(c) Suggest any two measures to encourage forestry identified in answer (a) in town or city.
(Application)

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Environmental Science ISC-Class XII

S.No. Questions

85. [Population and Conservation Ecology]
Read the paragraph carefully and answer the questions that follow.
Ecotourism is a novel approach for the tourism industry that involves travelling to natural
location without disturbing the eco-system integrity and creating opportunities for economic
benefits and well- being for the local communities. It provides a chance to relax to forget
worldly woes in the company of mother nature and to bolster efforts to save nature.

(a) Why is ecotourism called a novel approach to tourism? (Application)
(b) What is the difference between conventional tourism & ecotourism?
(Understanding)
(c) State three characteristic features of ecotourism. Cite one example of ecotourism.
(Recall)
(d) Why there is a need for ecotourism in the present day.
(Understanding)

86. [Monitoring Pollution]
Read the paragraph carefully and answer the questions that follow.
Air pollutants are dangerous substances present in the air. It is important to track the various
components of air. Monitoring air quality is a useful tool for estimating trends and detecting
patterns with respect to our environment and is used extensively in climate change studies.

(a) Name two each secondary air pollutants and primary pollutants.
(b) State four objectives of the air monitoring program.
(c) Name the document which ratified carbon credit. Mention three ways by which it can be
acquired by a country.
(d) Mention any two basic considerations that are to be taken care of during collecting sample
from any vicinity.
(Understanding)

87. [International Relations and the Environment]
Read the passage carefully and answer the questions that follow.
“The unique conditions are responsible for the formation of ozone hole over Antarctica.”
Source: The Times of India, Dec 2022
(a) When & which treaty was signed to protect the Ozone layer depletion?
(b) Explain briefly the unique conditions which are responsible for Ozone hole formation.
(c) Explain stepwise Chapman’s cycle of ozone formation in the higher layers of the
atmosphere. (Understanding)

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Environmental Science ISC-Class XII

ANSWER KEY

Q.No. Expected Answers

1. (b) Wastewater

2. (d) Steel

3. (b) Water Pollution

4. (b) An oil field's output decreases significantly after years of extensive drilling, leading
to an energy crisis.

5. (d) Q, R, and S.

6. (d) The village economy is in a very bad shape and lacks measures for progress.

7. (c) Problem- global warming – Cause- deforestation and industrialisation.

8. (c) R- P- Q- S

9. (d) Attains late sexual maturity.

10. (a) I and IV

11. (c) The principle of public participation denotes that industries polluting the environment
must be penalised.

12. (c) Turbidity

13. (a) 10,060

14. (d) Use of integrated pest management.

15. (b) It is an instrumental technique to monitor gaseous pollutants.

16. (b) Cryopreservation

17. (d) Bamako Convention

18. (d) A is false, but R is true.

19. (a) Both A and R are true, and R is the correct explanation of A.

20. (a) Both A and R are true, and R is the correct explanation of A.

21. (a) Both A and R are true, and R is the correct explanation of A.

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Environmental Science ISC-Class XII

Q.No. Expected Answers

22. (d) A is false, but R is true.

23. (c) A is true, but R is false.

24. (d) A is false, but R is true.

25. (a) Both A and R are true, and R is the correct explanation of A.

26. (b) Both A and R are true, but R is not the correct explanation of A.

27. (c) A is true, but R is false.

28. (d) A is false, but R is true.

29. (b) Both A and R are true, but R is not the correct explanation of A.

30. (c) A is true, but R is false.

31. (a) Both A and R are true, and R is the correct explanation of A.

32. (a) Both A and R are true, but R is not the correct explanation of A.

33. (a) Both A and R are true, and R is the correct explanation of A.

34. (d) A is false, but R is true.

35. (c) A is true, but R is false.

36. (c) A is true, but R is false.

37. (a) Both A and R are true, and R is the correct explanation of A.

38. (d) A is false, but R is true.

39. (b) Both A and R are true, but R is not the correct explanation of A.

40. (d) A is false, but R is true.

41. Trans Milenio

42. Secondary stage

43. Extension forestry

44. J-shaped/exponential

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Environmental Science ISC-Class XII

Q.No. Expected Answers

45. False. More salt/ impurities increase water conductivity.

46. True. Aquatic plants and animals can survive easily.

47. False- Low or high pH is lethal.

48. False- Suspended pollutants increase turbidity.

49. Tied Aid

50. Patent

51. Extended Producer Responsibility (EPR)

52. Dry Toilets

53. K strategists

54. Rachel Carson

55. Gary Snyder

56. Barry Commoner

57. Aldo Leopold

58. Dave Foreman/ Mike Rosella

59. Man and Biosphere (MAB) Programme

60. Forest Protection Committee

61. National Ambient Air Quality Standards

62. Non -Dispersive Infra-Red

63. Aquila Food Security Initiative

64. Ecofeminism.
The relationship between the oppression of women and the exploitation of nature is
fundamentally connected.
It is believed that women in developing countries are dependent on nature for their
survival.

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Environmental Science ISC-Class XII

Q.No. Expected Answers

65. (a) Sample ‘A’ has poor water quality, while sample ‘B has moderately clean water
quality.
(b) Dissolved oxygen is required for normal growth and survival of aquatic organisms.

66. (a) Micro-irrigation system/ sprinklers.
(b) One advantage and disadvantage (Each)
(i) Save water- the advantage is a uniform distribution of water.
(ii) Maintenance cost high/ initial setting up cost high/ damage by animals or weather
factors/time-consuming / labour intensive. (Any one disadvantage.)
67. GNP advantages – Easy to calculate, indicates economic conditions of the country,
measures value of good and services irrespective of location, compare the wealth of one
country with another.
GDP features-does not reflect inflation, only considers reported consumptions, does not
account quality of consumption, false indicator of economic health.

68. (a) DDT is a poisonous non-biodegradable chemical insecticide and it is neither depleted
nor metabolised. Hence, the concentration increases from the lower tier to the upper tier
(b) Biomagnification-Phenomenon which is caused by the accumulation of non-
biodegradable matter across the food chain.

69. (a) Defensive Expenditure
(b)
(i) Vaccination process.
(ii) Cleaning of beaches by the municipal corporation.
(iii) Adoption of clean techniques and processes in industry, and military expenditure for
the defense of the nation.
(iv) Waste management.
(v) Wastewater management.
(vi) Pollution abatement.
(vii) Protection of biodiversity and landscape. [Relevant examples will be accepted.]

70. (a) Figure A- Cotton and Figure B- Neel.
(b) These are cash crops/ commercial crops, British rule forced farmers to grow these for
export. It led to food scarcity in India.
[Other relevant examples of cash crops may be accepted.]

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Environmental Science ISC-Class XII

Q.No. Expected Answers

71. (a) Ceiling on land holding/ land ceiling act /Land reforms Act.
(b) Three reasons for the significance of this act are-:
• To reduce the disparity between rich landlords and landless.
• To improve agricultural productivity.
• To ensure food security for the poor.

72. (a) Food adulteration: It refers to the act of intentionally degrading the quality of food by
either adding or replacing the food substances with undeclared alternative components,
or by the removal of some valuable components.
(b) AGMARK and ISI are the two quality marks used to check food grade and its quality.
(c) Honey-Sugar/water, Gur Syrup and Pepper-Papaya seeds.

73. (a) Three reasons for the classification of waste as organic and inorganic-:
• Because organic waste is biodegradable, and inorganic is non-biodegradable.
• This leads to more efficient recycling of materials.
• This leads to less pollution.
• Helps economy.
(b) Composting.

74. (a)
• Pollution of water bodies for disposing of huge amounts of waste.
• Waste of fresh water for flushing purposes.
(b) DEWATs/Dry compost toilet/ Wet Compost toilet.
(Anyone to be explained.)

75. Differences between Biosphere Reserves and Sanctuaries

Biosphere Reserves Sanctuaries
An ecosystem with plants and animals of A place where birds or animals are
unusual scientific and natural interest. protected from being hunted.

Established under the MAB programme Formulated under the Wildlife Protection
of UNESCO. Act.

Ecosystem centric Species centric
Has core Core is absent.
Has buffer, and transition zone are Buffer zones are absent
present

76. Radiation/Pollution/ Climate change / global warming/ Deforestation / increasing
infrastructure projects.

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Environmental Science ISC-Class XII

Q.No. Expected Answers

77. (a) Demographic transition.
(b) It is defined as the transition from high birth and death rates to low birth and death
rates as a country develops from a pre-industrial to industrialised economy.
(c) Stage 1 depicts the pre-industrial age where the death and birth rates are very high and
stage 4 depicts the post-industrial age where the death and birth rates are very low.

78. Advise the central govt on any matter concerning the control of air pollution/ plan and
execute nationwide programs for controlling pollution; provide technical assistance and
guidance to the state boards for research work to control pollution; to organise training of
persons to be engaged in prevention and abatement of pollution; to organise mass media
campaigns regarding control of pollution/to lay down standards of air quality/ etc.

79. (a) Second law of ecology: “Everything must go somewhere”. It means that in nature,
there is no final waste, matter and energy are preserved, and the waste produced in one
ecological process is recycled in another. It restates a basic law of thermodynamics.
(b) Mangroves are natural and necessary vegetation as they protect us against tsunamis in
the sea. If we go against nature and cut down mangroves we must bear the consequences.

80. (a) Ivory trade in Africa.
(b) African elephant populations have drastically declined to less than 500,000 in the
current times, so the Ivory trade has to be banned by CITES.
(c) The number of elephants killed every year has decreased from 3500 (1980’s) to 50
(Present day). The increase in elephant numbers has given rise to undesirable elephant –
human conflict like crop raiding. The cost of preservation of an elephant is very high.
Large stocks of legally acquired ivory have become a liability. The cost of storage and
guarding against theft are too high for an unusable resource. (Any two points.)

81. Poor soil health, the dependence of farmers on external input, farmer suicides, reducing
crop returns, biodiversity loss (Any four points)
Sustainable agriculture: It should be ecologically sound, economically viable, socially
just, culturally appropriate and based on a scientific approach.
Proper selection of site, species and variety/ farming with more diversity/ focus on the
health of the soil/ natural, renewable and on-farm inputs/ serving indigenous variety of
seeds.

82. (a) A -log phase and C is the exponential phase.
(b) Resource limitation denotes the carrying capacity of the land.
(c)Competition/ natural disasters/ scarcity of food/ economic growth/self-
regulation/predation etc.

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Environmental Science ISC-Class XII

Q.No. Expected Answers

83. (a) Sarvodaya: Sarvodaya, meaning "the welfare of all," was a principle that Gandhi
championed as the foundation of a just and equitable society.
Antyodaya: Antyodaya, meaning "the rise of the last person," is closely related to
Sarvodaya but with a specific focus on the most marginalized and deprived sections of
society.
Decentralised self-governance: Panchayati Raj- His village policy was aimed at
empowering villages to be self-sufficient, socially harmonious, and free from exploitation,
reflecting his broader vision of a decentralized and self-reliant India.
(b) Reasons: Poverty reduction, equality, a sense of ownership and dignity of labour and
livelihood for all. Intermediate technology, which includes simple, small-scale, and labor-
intensive tools and processes, was more suitable for the economic conditions and skill
levels in villages. It was designed to be accessible and manageable by villagers
themselves, without the need for significant capital investment or technical expertise.
(c) Modern development: focus on mechanisation, reduced labour, pollution causing, for
luxury and non-essential goods.
Gandhi’s vision: local, geography and ecology-based, small cottage industries, labour
intensive, intermediate technology.

84. (a) Urban Forestry. It is defined as the practice of forestry in areas devoid of trees and
other vegetation situated in places away from the conventional forest areas, with the
objective of increasing the tree cover.
(b)
Social forestry Joint forest management
(1) Concerned with the areas lying outside Concerned with the forest areas
the forest/unused and fallow lands. itself.
(2) Aim to decrease the pressure on forest Treats people as partners and
resources and attempts to meet the needs of stakeholders in the management of
the people as well/safeguard facets from forests.
exploitation.
(3) Includes farm forestry, agroforestry, The forest protection committee and
urban forestry. forest department enter into an
agreement with the people in this
process of Joint Forest Management
(JFM).

(c) Planting trees along the roadside, traffic signals near schools and hospitals, railway
stations / tree plantation drives etc.

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Environmental Science ISC-Class XII

Q.No. Expected Answers

85. (a) Ecotourism mainly focuses on socially responsible travel, personal growth &
environment sustainability. Hence, it is called a novel approach.
(b) Conventional tourism does not involve environmental sustainability which is there in
ecotourism.
(c) Characteristics:
(i) Conscientious, low-impact visitor behaviour.
(ii) Sensitivity towards & appreciation of local cultures & biodiversity.
(iii) Support for local conservation efforts.
(iv) Environmental sustainability.
(d) Significance:
(i) Ecologically sustainable tourism.
(ii) Ecological awareness creation.
(iii) Educational importance.
(iv) Involvement of local communities & sharing of net benefits with them.

86. (a) Secondary- Acid rain, ozone; primary- CO2, SO2, CO, Nitric oxides, benzene, H2S.
(b) Background data, status and trend evaluation, identification of polluted cities,
behaviour of the environment, and air quality management. (any four points)
(c) Kyoto Protocol. Joint implementation, clean development mechanism, international
emissions trading
(d) The sample must be large, efficient sampling rate, well selected Scavenging duration,
continuous sampling, and pollutants must not alter during collection.
(any two points)

87. (a) Montreal Protocol; 1st January 1989.
(b) Antarctica is surrounded by water. The wind here blows in a clockwise direction
causing 'polar vortex'. This results in a static air mass over Antarctica which does not mix
with the air over the rest of the world. This continent is very cold. The low temperature
leads to the formation of polar stratospheric clouds (PSC) which consists of H2O and
HNO3 molecules. PSCs interact with CFC molecules and other halogenated compounds.
In spring, PSC melt and release halogenated molecules. During summer, the photons,
photolyze the halogenated compounds, freeing halogens that catalytically destroy ozone
layer.
(c) The step-by-step procedure of ozone creation is as under:

STEP 1: An oxygen molecule is photolyzed by solar radiation, creating two oxygen
radicals.
hv+ O2→2O
STEP 2: Oxygen radicals then react with molecular oxygen to produce ozone.
O2 +O.→O3
STEP 3: Ozone then reacts with an additional oxygen radical to form molecular oxygen.
O3+O.→2O2
STEP 4: Ozone can also be recycled into molecular oxygen by reacting with a photon.
O3+ hv→O2+O.

ISC Competency-Focused Practice Questions 32