NIOS Class 12 Biology Chapter 26 Terminal Exercises

The NIOS Biology Conservation and Use of Natural Resources chapter explains the importance of conserving water, forests, wildlife, and minerals. It emphasizes sustainable use of resources and human responsibility in protecting nature.

Students also learn about laws and practices supporting conservation. With solved terminal exercises, learners can practice and revise effectively. This chapter creates awareness and is essential for both exam preparation and building responsibility through NIOS Class 12 Biology studies.

NIOS Biology Conservation And Use Of Natural Resources

1. Define conservation.

Conservation is the proper management of a natural resource to prevent its exploitation, destruction, or degradation.

Conservation is the total of activities that can derive benefits from natural resources, but at the same time prevent excessive use leading to destruction or degradation.

2. What is meant by soil erosion?

The removal of top layers of soil by wind and water is called soil erosion. The top layers of soil contain humus and mineral salts, which are vital for the growth of plants. Thus, erosion causes a

significant loss of humus and nutrients, and decreases the fertility of the soil.

3. Define the term biodiversity.

Biodiversity can be defined as the flora and fauna, i.e. variety of all plants, animals, and microbes of a region. It is essential for the maintenance of the ecosystem. It maintains the gaseous composition of the atmosphere, controls climate, helps in natural pest control, pollination of plants by insects and birds, soil formation and conservation, water purification and conservation, geochemical cycles, etc.

4. State the meaning of sustainable development.

Sustainable development is the development that meets the needs of the present

generation and conserves resources for the future generation.

Sustainable development should include –

• reducing excessive use of resources and enhancing resource conservation.
• Recycling and reuse of waste materials.
• Scientific management of renewable resources, especially bio-resources.
• Planting more trees.
• Green grassy patches are to be interspersed between concrete buildings.
• Using more environmentally friendly materials or biodegradable materials.
• Use of technologies that are environmentally friendly and based on efficient use of resources.

5. Mention any two methods of conservation of energy resources.

• Worshipping certain plants like banyan, peepal, tulsi, etc., has not only preserved them but also encouraged their plantation.
• Natural resources were conserved in the form of sacred groves/forests, sacred pools and lakes, sacred species, et,c e.g., the river Ganges.

6. Why should wildlife be conserved?

Wildlife needs to be conserved for:

• Maintaining ecological balance to support life.
• Preserving different kinds of species (biodiversity).
• Preserving economically important plants and animals.
• Conserving the endangered species.

7. Why is soil considered both a renewable and a non-renewable resource?

Soil is both a renewable as well a non-renewable resource.

• Soil is renewable because its productivity can be maintained with fertilizers and manures rich in humus.
• If the soil has been removed from a certain place by erosion, it is practically non-renewable because the formation of new soil may take hundreds or thousands of years.

8. State any three reasons for the degradation of water.

The main reasons for the degradation of water are:

• 1. To meet the needs of an increasing population, surface water (water from ponds, lakes, rivers, etc) and groundwater are overdrawn, depleting the volume of water.
• 2. Sewage, i.e., wastewater from domestic and municipal use, makes fresh water unfit for use by human beings and animals.
• 3. Waste water from all industries flows down into the surface water bodies and ground water bodies, and they get polluted.
• 4. Agricultural wastes containing manure, fertilizers, and pesticides enter the water bodies and degrade the quality of water.
• 5. The continuous decrease of the groundwater level along coastal regions often causes movement of saline seawater into freshwater wells, thus spoiling their water quality.

9. Distinguish between in-situ and ex-situ conservation strategies.

• (i) In-situ (on-site conservation includes the protection of plants and animals within their natural habitats or in protected areas. Protected areas are areas of land or sea dedicated to the protection and maintenance of biodiversity. For example: e.g., National Parks, Wildlife Sanctuaries, Biosphere Reserves, etc.
• (ii) Ex-situ (off-site) conservation is the conservation of plants and animals outside their natural habitats. These include Botanical Gardens, Zoo, Gene Banks, DNA Banks, Seed Banks, Pollen Banks, Seedling and Tissue Culture, etc.

10. Describe natural gas as a conventional source of energy.

Natural gas is part of fossil fuels that are obtained from fossilised remains of plants and animals, which have transformed into natural gas over millions of years. LPG, Liquefied Petroleum Gas, is a byproduct of petroleum refineries. 

11. Describe the natural and the anthropogenic causes of soil erosion.

(a) Natural Causes of Soil Erosion

Erosion of soil takes place due to the effect of natural agents like wind and water. High velocity winds over land, without vegetation, carry away the loose topsoil. Similarly, in areas with no or very little vegetation, pouring raindrops carry away the soil.

(b) Anthropogenic Causes of Soil Erosion

• 1. Deforestation: If the forests are cut down for timber, or for farming purposes, or for construction, then the soil is no longer protected from the effects of falling rain. Consequently, the topsoil is washed away into the rivers and oceans.
• 2. Poor farming methods: Improper tillage and failure to replace humus after successive crops, and burning the stubble. The short, stiff stalks of grain or hay remaining on a field after harvesting of weeds reduce the water-holding capacity of the soil. So the soil becomes dry and can be blown away as dust.
• 3. Overgrazing: Overgrazing by flocks of cattle, buffalo, goats, and sheep leaves very little plant cover on the soil. Their hooves make the soil dry, and the soil can be blown away easily.

12. Describe the various methods of conservation of soil.

Soil conservation means checking soil erosion and improving soil fertility by

adopting various methods.

• 1. Maintenance of soil fertility: The fertility can be maintained by adding manure and fertilizers regularly, as well as by the rotation of crops.
• 2. Control on grazing: Grazing should be allowed only on specified areas.
• 3. Reforestation: Planting of trees and vegetation reduces soil erosion.
• 4. Terracing: Dividing a slope into several flat fields to control the rapid run of water. It is practised mostly in hilly areas.
• 5. Contour ploughing: Ploughing at right angles to the slope allows the furrows to trap water and check soil erosion by rainwater.

13. Future generations of mankind will depend more and more on non-conventional sources of energy. Discuss.

The faster depletion of conventional sources of energy has forced mankind to look for non-conventional sources of energy. Such non-conventional sources might be the only source of energy in the near future when fossil fuels are no longer available. 

14. Explain any five methods of conservation of water.

Conservation and management of water are essential for the survival of mankind,

plants, and animals. This can be achieved by adopting the following methods:

• 1. Growing vegetation in the catchment areas, which will hold water in the soil and allow it to percolate into deeper layers and contribute to the formation of groundwater.
• 2. Constructing dams and reservoirs to regulate the supply of water to the fields, as well as to enable the generation of hydroelectricity.
• 3. Sewage should be treated, and only the clear water should be released into the rivers.
• 4. Industrial wastes (effluents) should be treated to prevent chemical and thermal pollution of fresh water.
• 5. Judicious use of water in our day-to-day life.
• 6. Rainwater harvesting should be done by storing rainwater and recharging groundwater.

15. Describe any three non-conventional sources of energy.

• Solar energy was abundant, everlasting, and available everywhere. Solar cookers, solar hot water systems, solar dryers, solar air heaters, etc, are a few examples. 
• Hydro energy from falling water is cheaper than thermal and nuclear energy. Water from dams is made to fall to rotate turbines that generate electricity. 
• Wind energy is mechanical energy that is used to generate electricity in coastal and hilly areas. 
• Tidal energy uses the water movements during high and low tide to turn the turbines to generate electricity. 
• Nuclear energy uses uranium and thorium that disintegrate spontaneously and trap this energy to produce electricity. 
• Hydrogen energy uses hydrogen as the fuel source. 
• Geothermal energy utilises the volcanic regions where the water sources are naturally heated. This hot water is used to make steam, and from there, electricity. 
• Biogas generated as a result of microbial activity can be used to generate methane gas, which can be used as cooking gas or to generate electricity. 

Biofuel is liquid hydrocarbons produced by plants such as Jatropha curcus is another potential source of non-conventional energy.

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