Environmental Science PYQ Oct 2024 68/SS/O

NIOS Class 12 Environmental Science Question Paper 2024

CORE MODULES

OBJECTIVE QUESTIONS TYPE – I

1. The order of correct sequence of human evolution among the following is: 1

(a) Homo habilis

(b) Homo erectus

(c) Australopithecines

(d) Homo sapiens

(A) (c), (a), (b), (d)

(B) (a), (b), (c), (d)

(D) (c), (d), (b), (a)

Ans: (D) (c), (d), (b), (a)

2. One of the consequences of Global warming can be: 1

(A) Allows heat radiation given out by earth will escape.

(B) Large fish will move to cooler areas and thrive.

(D) Sea levels will be decreased.

Ans: (C) Global temperature will be raised.

3. Counting of human population is called: 1

(A) Census

(B) Natality

(D) Mortality

Ans: (A) Census

4. Rural folks are more homogeneous socially due to: 1

(A) The Caste System

(B) Follow of Indian Samvat

(D) Simple living

Ans: (A) The Caste System

5. Deforestation refers to: 1

(A) Non-forest areas being converted to forest.

(B) Agriculture pasture being converted to forest.

(D) Loss of tree cover from a land.

Ans: (D) Loss of tree cover from a land.

6. The Great Indian Bustard is a rare species of India as categorized by IUCN because: 1

(A) Its Numbers are continuously decreasing.

(B) They live in unusual environment (endemics) and are few in numbers.

(D) Their status is not known.

Ans: (B) They live in unusual environment (endemics) and are few in numbers.

7. A more productive ecosystem than ocean or freshwater is: 1

(A) Mangrove

(B) Estuary

(D) Lakes

Ans: (B) Estuary

8. The base of an ecological pyramid consists of: 1

(A) Herbivores

(B) Carnivores

(D) Omnivores

Ans: (C) Producers

9. Under the Montreal protocol ammended in 1990 it was decided to completely phase out :

(A) CNG

(B) Tetraethyl lead

(D) SPM

Ans: (C) CFC

10. The phenomenon of nutrient enrichment of a water body is called its: 1

(A) Biological demand for oxygen

(B) Point source depletion

(D) Point source pollution

Ans: (C) Eutrophication

11. The ‘Carrying Capacity’ of the environment refers to the: 1

(A) Availability of many resources

(B) Maximum load that the environment can withstand.

(D) Rate of consumption of natural resources

Ans: (B) Maximum load that the environment can withstand.

12. The substitute for petroleum in some conventional engines which is obtained from vegetable

oil is :

(A) Ethanol

(B) Biogas

(D) CNG

Ans: (C) Biodiesel

13. The provision for penalties or punishment to prevent poaching and illegal trade was introduced

in the :

(A) Biodiversity Act

(B) Project Elephant

(D) Wildlife Act

Ans: (D) Wildlife Act

OPTIONAL MODULE – A WATER RESOURCE MANAGEMENT

14. The untreated household water which has not came into contact with toilet waste is :

(A) Wastewater

(B) Greywater

(D) Black water

Ans: (B) Greywater

15. TBS water conservation model was pioneered by: 1

(A) Mangu Ram

(B) Rajendra Singh

(D) Jaiprakash Narayan

Ans: (B) Rajendra Singh

16. Artificial recharge, percolation tank method and catchment area protection are techniques

to manage and conserve :

(A) Rainwater

(B) Groundwater

(D) Recycled water

Ans: (B) Groundwater

OPTIONAL MODULE – B ENERGY AND ENVIRONMENT

14. Photovoltaic cells are made up of silicon and are used to convert: 1

(A) Electrical energy into solar energy

(B) Hydropower to electrical energy

(D) Solar energy to electrical energy

Ans: (D) Solar energy to electrical energy

15. The highly efficient power-generating system that produces electricity by combining fuel and oxygen in electrochemical reaction is :

(A) Biomass

(B) Fuel cell

(D) Geothermal cells

Ans: (B) Fuel cell

16. CFL, ecohouse and solar kitchen concepts are related to an: 1

(A) Energy-deficient town

(B) Energy-neutral town

(D) A non-renewable energy technique

Ans: (C) Energy-efficient town

CORE MODULES

OBJECTIVE QUESTIONS TYPE – II

17. Write the names of the kind of forests found in India on the basis of features listed below.

(a) Tropical trees found in Chhota Nagpur plateau, which cast their leaves for about 6 to 8 weeks in summer.

(b) Trees which are found in places with plenty of rainfall and sunshine throughout the year.

Ans:

a) Tropical deciduous trees
b) Tropical rainforests

18. Answer the following questions in one or two sentences. (15-20 words) 1×6=6

(1) Intake of groundwater with increased level of nitrates by infants results in a kind of anaemia. Name the condition.

(2) Himalayan and peninsular regions are covered with endemic flora. What do you understand by the term endemic?

(3) Internal migration within a country does not affect its total population size. Why?

(4) How floating masses of water hyacinth help in removing pollutants from wastewater.

(5) What are the three zones of a biosphere reserve?

(6) Azolla bio fertilizers has one limiting factor. What is it?

Ans:

1) Methaemoglobinaemia
2) Endemic are those plant and animal species that are local, i.e. not found anywhere else.
3) Because the internal migration within the country is usually from rural areas to the urban sector.
4) Growing algae or floating masses of water hyacinth also helps in cleaning the water polluted by absorbing phosphates, nitrates and other nutrients.
5) A Biosphere Reserve consists of core, buffer and transition zones. The transition zone is where settlements are allowed.
6) It is an aquatic plant, and water becomes a limiting factor in growing it, particularly in summer.

19. Answer the following questions in one word only: 1×6=6

(1) An appropriate technique for efficient clean up from garbage accumulation and can be prepared in the backyard of your home.

(2) A cropping practice in which two or more crops are grown all at the same time.

(3) Name the act which aims at regulating access to biological resources so as to ensure equitable sharing of benefits arising from their use.

(4) Identify the legislation/act which provides for setting up of National biodiversity authority and state biodiversity boards.

(5) The process of reusing wastewater from industrial or domestic sources after poper treatment.

(6) A measure of biologically productive area of earth required per person to produce required resources and to absorb the waste produced.

Ans:

(1) Vermicomposting
(2) Intercropping
(3) Biodiversity Act
(4) Biological Diversity Act
(5) Recycling of water
(6) Ecological footprint

20. Fill in the blank by using appropriate words given below: 1×4=4

(Impact assessment agency, Ramsar Convention, Kyoto Protocol, Montreal Protocol)

(a) A frame work for international co-operation for the conservation and wise use of wetland and habitats is __________.

(b) The convention for the protection of Ozone layer is __________.

(c) Convention held in Japan on climate change objectives is __________.

(d) ‘Go ahead’ signal or the environmental clearance is granted by __________ in the Ministry of Environment and forests.

Ans:

(a) Ramsar Convention
(b) Montreal Protocol
(c) Kyoto Protocol
(d) Impact Assessment Agency

21. Write the following statement is true or false. 1×3=3

(a) Five star refrigerator is least efficient than one star refrigerator.

(b) Nile perch, an exotic predatory fish eliminated small Cichlid fish in a freshwater aquatic system.

(c) Poor sex ratio of a country is suggesting that there is no discrimination between male and female child.

Ans:

(a) False

(b) True

OPTIONAL MODULE – A WATER RESOURCE MANAGEMENT

22. Certain aquatic areas requires special protection. Why? 1

Ans: A large number of areas in our aquatic environment support rare species of aquatic and amphibious plants and animals, and are, therefore, ecologically very sensitive. They need special protection.

23. Write two precautions while storing rain-harvested water in cisterns. 1

Ans:

Debris and leaves should be filtered before storing the water by placing screens over gutters or downspouts.
Water kept in tanks or cisterns should also be covered to minimise algal growth and eliminate the potential for mosquito breeding.

24. Watershed management helps in promoting water conservation. How? 1

Ans: A watershed is an area through which a water body gets its water. Protection of forests and vegetation helps conserve water in a watershed. The water passing through a forested watershed is generally clean.

OPTIONAL MODULE – B ENERGY AND ENVIRONMENT

22. Wind energy is an indirect form of solar energy. Justify. 1

Ans: About 2% of the sunlight striking the earth is converted into the kinetic energy of moving

air called wind. This is why wind energy is an indirect form of solar energy.

23. Jatropa curcas is considered as an important petro plant. Why? 1

Ans: Jatropa curcas can produce hydrocarbons in substantial amounts and can act as an alternative energy source, which are called petrocrops.

24. What does process modification mean in energy conservation in industry? 1

Ans: Process modification means the replacement of old and more energy-consuming processes with new energy-efficient processes.

CORE MODULES

SUBJECTIVE PART

25. Fill in the blanks 1 to 4, based on four factors on which density of a population depends.

Ans:

1. Immigration
2. Mortality
3. Emigration
4. Natality

How is xerarch succession different from hydrarch?

Ans: Succession that occurs on land where the moisture content is low, e.g. on bare rock, is known as xerarch. Succession that occurs in a water body, such as a pond or lake, is called hydric succession.

26. How is rural society different from urban society with reference to following factors?

(a) Community size

(b) Population density

Ans:

	Rural Society	Urban Society
Community size	Small	Much larger than rural community.
Population density	Comparatively lower density of population	Large population density.

27. Write two ways by which development can take place without causing damage and destruction to environment.

Ans: Practice sustainable development, such as

Use renewable energy sources such as solar energy and natural gas.
Reduce waste generation by reusing and recycling things as much as possible.

28. Deforestation leads to soil erosion. Justify. 2

Ans: Trees intercept rainfall, and cutting down trees and removing plants leads to soil erosion. Plants’ roots hold the soil in place. With the loss of protective cover of plants, the topsoil, rich in organic matter, is washed away, and the soil loses its fertility.

29. How is environmental legislation important for environment improvement and conservation?

Ans: There should be effective legislation to protect the environment, or else the need for resources by the growing population will create havoc on the environment. The other important aspect is the enforcement of these laws. To safeguard our environment from further degradation and pollution, these laws must be enforced forcefully and effectively.

30. State what is biological diveristy? Which are the three different levels at which biological diversity should be considered?

Ans: All forms of life, including plants, animals, and microorganisms in nature, constitute biological diversity. biodiversity. Biological diversity is usually considered at three different levels:

a) genetic diversity, i.e. at the genetic level
b) species diversity, i.e. at the level of species
c) ecosystem diversity, i.e. at the level of the ecosystem.

31. State two reasons for migration of rural folk towards cities. 2

Ans:

For better opportunities: Apart from agriculture and cottage industries for crafts, villages do not offer opportunities for any other vocation, whereas cities have many avenues for jobs. Also, schools are not well-equipped, and there are hardly any institutions for higher studies.
For a better lifestyle: Superstitions, social taboos and criticism hold back forward-looking villagers from improving life style, so they rush towards cities. Also, cities are consistently into trade and economic expansion as well as territorial expansion.

Tribal communities were able to live in forest without harming it. Which two ways of their living should we embrace?

Ans: Tribal people used ecologically sound agricultural practices, and the knowledge of such practices was passed on to the next generations for centuries.

They grew multiple crops simultaneously for some years, and then plots were left to recover and grow back into forests.
They have cultural and economic ties with the forest they live in and have the ability to sustain it and protect it.

32. Examine the case of Thar desert and identify a mammal, a bird, a plant which are now in the list of endangered species. Also mention a national bird which is well protected by people.

Ans:

Mammal: Indian gazelle
Bird: The great Indian bustard
Plant: Khejri
National Bird: Peafowl

What do you understand by desertification? Which human activity in Thar desert makes regeneration of plant process in the desert very difficult?

Ans: Desertification is the diminution or destruction of the biological potential of the land, which can ultimately lead to desert-like conditions.

Desertification is a natural phenomenon, but it is often accelerated by human activities. They are uncontrolled grazing, indiscriminate cutting of forests, excessive mining, uneconomic use of agricultural land, and exploitation of water resources.

33. In which two groups radiations can be categorized? Give an example of each group. Write the possible damages caused to humans by radiation pollution.

Ans: Radiations can be categorised into two groups, namely the non-ionising radiations and the ionising radiations.

Non-ionising radiations are constituted by the electromagnetic waves at the longer wavelength of the spectrum, ranging from near infra-red rays to radio waves.
Ionising radiations cause ionisation of atoms and molecules of the medium through which they pass. Electromagnetic radiations such as short wavelength ultra violet radiations (UV).

The biological damage resulting from ionizing radiations is generally termed radiation damage. Large amounts of radiation can kill cells, which can dramatically affect the exposed organism as well as possibly its offspring. Affected cells can mutate and result in cancer. A large enough dose of radiation can kill the organism.

How can disease-causing pathogens reach humans? List all modes of transmission with one example each.

Ans: Disease-causing pathogens reach humans in various ways, which are described below.

1. Contact transmission: Some diseases can be transmitted by either direct physical contact with the infected person, or the causative agent can be transmitted to the host indirectly by contact with the infected articles.
2. Vehicle transmission:
- (a) Pathogenic organisms are transmitted through water, food, etc. When the water is infected at the source, it spreads the infection to large populations. Pathogens causing cholera, typhoid, and Hepatitis are transmitted from one person to another through their domestic water supply.
- (b) Many chemical pollutants, such as food additives, adulterants, poisonous industrial waste, pesticides and metals, get mixed with water, including underground water and are consumed by humans and animals, resulting in diseases. Inadequate water supply and lack of personal hygiene cause transmission of diseases such as trachoma in the eye and skin infections.
3. Vector transmission: A vector is a carrier of the pathogen. Mosquitoes spend a part of their life cycle in water. Vector for diseases such as malaria, yellow fever, encephalitis, filaria and dengue.

34. You are invited to give a talk on how exotic species can cause biodiversity depletion. Give four examples and highlight the biodiversity loss due to exotic species.

Ans: A few examples are-

(i) Parthenium hysterophorus (Congress grass- a tropical American weed) has invaded many of the vacant areas in cities, towns and villages in India, leading to the removal of the local plants and the dependent animals.
(ii) Nile perch, an exotic predatory fish introduced into Lake Victoria (South Africa), threatened the entire ecosystem of the lake by eliminating several native species of the small Cichlid fish that were endemic to this freshwater aquatic system.
(iii) Water hyacinth clogs lakes and riversides and threatens the survival of many aquatic species. This is common in the Indian plains.
(iv) Lantana camara (an American weed) has invaded many forest lands in various parts of India and wiped out the native grass species.

35. ‘Cycling of Nitrogen is vitally important for all living organisms’. Write one sentence each on the five main processes essential for nitrogen cycle.

Ans: Five main processes are essential for the nitrogen cycle, which are elaborated below.

(a) Nitrogen fixation: This process involves the conversion of gaseous nitrogen into Ammonia, a form in which it can be used by plants. Atmospheric nitrogen can be fixed by the following three methods:-
- (i) Atmospheric fixation: Lightning, combustion and volcanic activity help in the fixation of nitrogen.
- (ii) Industrial fixation: At high temperature (400 °C) and high pressure (200 atm.), molecular nitrogen is broken into atomic nitrogen, which then combines with hydrogen to form ammonia.
- (iii) Bacterial fixation: There are two types of bacteria-
  - (i) Symbiotic bacteria, e.g. Rhizobium, in the root nodules of leguminous plants.
  - (ii) Freeliving or symbiotic, e.g. 1. Nostoc 2. Azotobacter 3. Cyanobacteria can combine atmospheric or dissolved nitrogen with hydrogen to form ammonia.
(b) Nitrification: It is a process by which ammonia is converted into nitrates or nitrites by Nitrosomonas and Nitrococcus bacteria, respectively. Another soil bacterium, Nitrobacter, can convert nitrate into nitrite.
(c) Assimilation: In this process, nitrogen fixed by plants is converted into organic molecules such as proteins, DNA, RNA, etc. These molecules make up the plant and animal tissue.
(d) Ammonification: Living organisms produce nitrogenous waste products such as urea and uric acid. These waste products, as well as dead remains of organisms, are converted back into inorganic ammonia by the bacteria. This process is called ammonification. Ammonifying bacteria help in this process.
(e) Denitrification: Conversion of nitrates back into gaseous nitrogen is called denitrification. Denitrifying bacteria live deep in soil near the water table as they like to live in oxygen free medium. Denitrification is the reverse of nitrogen fixation.

36. When does an occupational health hazard arise? What is the common name of black lung disease? Which people suffer the most from it? Write its causes, symptoms and ways of prevention.

Ans: For some, the work environment exposes them to health hazards that contribute to injuries, respiratory diseases, cancer, musculoskeletal disorders, reproductive disorders, cardiovascular diseases, mental and neurological illnesses, and hearing loss, etc. Such health hazards are termed occupational health hazards, being associated with an occupation.

Black lung disease is the common name for pneumoconiosis (CWP) or anthracosis, a lung disease of older workers in the coal industry, caused by inhalation over many years of small amounts of coal dust.
- The particles of fine coal dust accumulate in the lungs, as they cannot be destroyed within the lungs or removed from them. Eventually, this build-up causes thickening and scarring, making the lungs less efficient in supplying oxygen to the blood.
- The primary symptom of the disease is shortness of breathe which gradually gets worse as the disease progresses. In severe cases, it may eventually cause heart failure. In some cases, a progressive massive fibrosis develops, in which damage continues in the upper parts of the lungs even after exposure to dust has ended.
- The only way to prevent black lung disease is to avoid long-term exposure to coal dust. Coal mines may help prevent this condition by lowering the coal dust level and providing protective clothing to coal miners.

What are the reasons for rapid decline of biodiversity? List any five reasons.

Ans: Rapid decline of biodiversity is a result of various causes.

(1) Loss of habitat: Due to the growing human population, wetlands are being drained through landfills, as the demand for land increases. Natural forests are cleared for industry, agriculture, dams, habitation, recreational sports, etc. As a consequence, every plant and animal species occupying that ecosystem is temporarily or permanently affected. So are the migrating birds or other animals visiting that habitat.
(2) Pollution: Pollution that leads to the greenhouse effect results in global warming. All those species that are slow to adjust to the changed environment are eventually lost.
(3) Overuse: Whales for oil, fish for food, trees for wood, plants for medicines, etc., are being removed by humans at higher rates than they can be replaced.
(4) Introduction of foreign species: Many new species are introduced intentionally and unintentionally into new regions thrive at the expense of native species. For example, Parthenium, Argemone and Lantana are the common weeds of foreign origin in our country.
(5) Environmental degradation: Global warming, increased CO₂ concentration in the atmosphere, nuclear radiation, UV-exposure, oil spills, etc.

OPTIONAL MODULE – 8A WATER RESOURCE MANAGEMENT

37. What are the major water quality issues in context of India. 2

Ans: All kinds of activities, urban, industrial, or agricultural, carried out on land have the potential to contaminate groundwater.

Industrial discharges, landfills, and subsurface injection of chemicals and hazardous wastes are obvious sources of groundwater pollution. These concentrated sources can be easily detected and regulated, but the more difficult problem is associated with diffuse sources of pollution like leaching of agrochemicals and animal wastes, subsurface discharges from latrines and septic tanks, and infiltration of polluted urban run-off and sewage where sewerage does not exist or is defunct.

38. Suggest four benefits of rainwater harvesting to the people facing scarcity of water. 2

Ans: Some of the benefits of rainwater harvesting are as follows:

Increases water availability;
Check the declining water table.
It is environmentally friendly;
Improves the quality of groundwater through the dilution of fluoride, nitrate, and salinity;
Prevents soil erosion and flooding, especially in urban areas.

Which two ways will you adopt to conserve groundwater in your City/Village?

Ans:

Artificial recharge: Water is spread over the ground to increase the area and length of time for water to remain in contact with the soil, to allow maximum possible opportunity for water to enter the ground.
Percolation tanks are constructed across the water course for artificial recharge.

39. List any four government’s efforts on water conservation. 2

Ans:

Several initiatives are taken by the government of India and various state governments to promote rainwater harvesting in the country.
Many local bodies are considering making it mandatory to install a rainwater harvesting system in housing complexes, large buildings and offices.
A large number of dams and reservoirs created in the country are good examples of the government’s efforts in water conservation.
There are several policy and regulatory initiatives taken by the government to promote rainwater harvesting and water conservation.

Management of crops growing pattern should be made aware to farmers. What advice will you give regarding this to conserve water in water scarce area?

Ans: In water-scarce areas, the crop selection should be based on the efficiency of the crop to utilise the water. Some of the plants suitable for water-scarce areas are

(i) plants with shorter growth periods
(ii) high-yielding plants that require no increase in water supply
(iii) plants with deep and well-trenched roots
(iv) plants which cannot tolerate surface irrigation.

OPTIONAL MODULE – 8B ENERGY AND ENVIRONMENT

37. Solar kitchen is an energy-efficient building. How are meals cooked in this kitchen? 2

Ans: Solar kitchen is a community kitchen and is constructed for preparing 2000 meals a day. Since solar energy is abundant in southern India, using steam as the heat transfer medium for preparing the meals was the obvious choice. Solar kitchen possesses the following features

Compressed earth blocks
10m long ferro-cement roof channels
Decentralised wastewater system consisting of an Imhoff tank, baffled reactor and polishing pond.
Solar bowl concentrator of 15m diameter.
Scheffler community cooker concentrator

38. Which four alternative natural sources of energy can be used in order to conserve fossil fuels?

Ans:

Geothermal energy
Hydrogen energy
Wind energy
Plants that produce hydrocarbons for biofuel
Fuel cell technology

What are the limitations of alternative energy sources?

Ans:

The limitation of solar energy is that on a cloudy day or in winter, it is not available, and the current technologies are fairly limited.
Tidal power is another renewable energy resource, but suitable sites for harnessing this energy are limited, and technologies are few.
Fuel Cells have a high initial cost, which is still the biggest hurdle in the widespread commercialisation of fuel cells.
Steam from geothermal plants contains hydrogen sulphide gas, which has the odour of rotten eggs, and causes air pollution.

39. Which behavioural changes in human will positively result in energy conservation?

Ans:

For the right attitude towards energy conservation, residents should be encouraged to drive less, walk and bike more by installing bike racks at public buildings.
Switch off the lights while leaving the room, shut down the computers when not in use, unplug appliances whennot in use etc.
Lower the thermostats in the winter and raise them in the summer.
Household and business wastes should be recycled. It will positively result in energy conservation.

How can solar energy be used for cooling purposes?

Ans: A solar collector can also be used for cooling. In this system, energy from the sunlight powers a small heat engine similar to an electric motor of a refrigerator. The heat engine drives a piston that compresses a special vapour into a liquid; the liquid then revapourizes and draws heat out of the surrounding air.