Chapter 30: HUMAN IMPACT ON ENVIRONMENT

Chapter 30: Human Impact on Environment Class 10 Science and Technology (212) NIOS Textbook Solutions

Chapter 30. HUMAN IMPACT ON ENVIRONMENT

INTEXT QUESTIONS 30.1

1. Define the term ‘natural disaster’? Name any three.

Answer: A natural disaster is an environmental problem caused by natural factors and not by humans. It causes damage to life, property and the environment.

Any three natural disasters are earthquake , flood and cyclone.

2. You are enjoying a cup of tea with your family sitting on a bed. Suddenly you experience an earthquake . List the first two steps that you and your family should take.

Answer: If an earthquake occurs while you and your family are sitting on a bed, the first two steps you should take are:

(i) Creep under a sturdy bed or table to protect yourself from falling objects.

(ii) Cover your head and neck with your arms, a pillow, or any other protective material nearby until the shaking stops.

3. State one cause each of (a) forest fire (b) landslide (c) Flood

Answer: (a) Forest fire: Lightning striking dry twigs.
(b) Landslide: Cutting of trees (deforestation).
(c) Flood: Heavy rainfall.

4. State any one way by which National Disaster Management Authority of India could help in reducing the loss of life in case of (a) cyclone (b) tsunami.

Answer: (a) Cyclone: The National Disaster Management Authority (NDMA) can issue early warning alerts and evacuate people to safe shelters.

(b) Tsunami: The NDMA can provide early tsunami warnings and evacuate people from coastal areas to safer places.

5. What happens after a cloudburst?

Answer: After a cloudburst, flash floods and landslides may occur due to sudden, very heavy rainfall in a short period.

INTEXT QUESTIONS 30.2

Fill in the blanks.

1. The number of animals, such as __________ and___________ is falling due to cutting of forests.

2. Need for ___________ leads to felling of trees.

3. Practice of ___________ and ___________ can help in reforestation.

4. Environmental problems, such as __________ and ____________ are a result of increase in human population.

Answer: 1.  The number of animals, such as cheetah and tiger is falling due to cutting of forests.

2. Need for housing (or construction of roads / industrialization) leads to felling of trees.

3. Practice of silviculture and mass plantation can help in reforestation.

4. Environmental problems, such as air pollution and water pollution (or global warming) are a result of increase in human population.

INTEXT QUESTIONS 30.3

Fill in the blanks.

1. _____________ and ____________ are examples of natural resources of water pollution.

2. Thermal discharge into rivers may lead to the death of ___________.

3. Presence of _________ and _________ in water may lead to infectious diseases.

4. Enrichment of water bodies with nutrients coming from fields is called _________.

5. Non-biodegradable wastes, such as ________ may lead to biomagnifications upon entering the food chain.

6. Domestic sources, such as _________ and _________lead to land pollution.

7. Unwanted sound may lead to_____________ pollution.

8. Noise pollution may be caused by___________ and __________ .

Answer: 1. Excreta (Animal/Human) and agricultural water are examples of natural resources of water pollution.

2. Thermal discharge into rivers may lead to the death of fish.

3. Presence of human and animal excreta in water may lead to infectious diseases.

4. Enrichment of water bodies with nutrients coming from fields is called eutrophication.

5. Non-biodegradable wastes, such as DDT may lead to biomagnifications upon entering the food chain.

6. Domestic sources, such as plastic bags and kitchen waste lead to land pollution. 

7. Unwanted sound may lead to noise pollution.

8. Noise pollution may be caused by vehicles and loudspeakers.

TERMINAL EXERCISES

1. Choose the correct option                 

(i) Growing tress for afforestation is called

(a) Monoculture    (b) horticulture   (c) Silviculture   (d) agriculture

Answer: (c) Silviculture.

[ Silviculture is the practice of growing and managing trees for afforestation, reforestation, or timber production.]

(ii) Which of the following chemicals lead to depletion of the ozone layer?

(a) Carbon dioxide (b) Chloro-fluorocarbons   (c) Nitrogen (d) Water vapour

Answer: (b) Chloro-fluorocarbons (CFCs).

[ CFCs, once used in refrigerants and aerosols, rise to the stratosphere where UV radiation breaks them down, releasing chlorine atoms. These chlorine atoms catalytically destroy ozone molecules, leading to ozone layer depletion.]

(iii) Which of the following can be found in the body of top consumers in high concentration?

(a) Nitrates    (b) Phosphates    (c) DDT    (d) Vitamins

Answer: (c) DDT.

[ DDT is a non-biodegradable pesticide that accumulates in the bodies of organisms. As it moves up the food chain through biomagnification, its concentration increases progressively, reaching the highest levels in top consumers like eagles, humans or large fish.]

(iv) Soil erosion can be prevented by

(a) Use of pesticides     (b) deforestation    (c) Afforestation    (d) excessive use of fertilizers

Answer:  (c) Afforestation.

[ Afforestation (planting trees) helps bind the soil with tree roots, reducing runoff and preventing soil erosion.]

2. Which of the following are biodegradable?

Aluminum foil, paper, ballpoint pen refill, grass

Answer: The biodegradable items are paper and grass .

3. Which gaseous pollutant has the ability to absorb infra-red radiations?

Answer: Carbon dioxide (CO₂) is the gaseous pollutant that has the ability to absorb infrared (IR) radiations. It traps heat in the Earth's atmosphere, causing the greenhouse effect and contributing to global warming.

4. A chemical factory in a village discharges its waste that is rich in nitrogen, in a pond. Which phenomenon do you expect to take place?

Answer: The phenomenon is eutrophication. The nitrogen-rich waste increases nutrients in the pond, causing rapid growth of algae. When the algae die and decompose, dissolved oxygen in the water decreases. As a result, fish and other aquatic animals die due to lack of oxygen.

5. Leakage of gases used in refrigerators and air conditioners for cooling are not considered eco-friendly. Why?

Answer: Leakage of gases used in refrigerators and air conditioners, such as CFCs, is not eco-friendly because they damage the ozone layer. This allows more harmful ultraviolet (UV) rays to reach the Earth, causing health problems and harming the environment.

6. A ship carrying oil from the gulf region collides with huge rocks and gets damaged. Is this just news or has some serious consequences? Give your opinion in one sentence.

Answer: It has serious consequences because the spilled oil causes oil pollution, which harms marine plants and animals and disturbs the aquatic ecosystem.

7. Give the term given to replenishment of the forests from where wood can occasionally be taken for commercial use?

Answer: It is the practice of replenishing forests by planting new trees and managing them properly so that wood can be taken occasionally for commercial use without destroying the forest.

8. List two ways of replenishing forests.

Answer:  Two ways of replenishing forests are :

(i) Afforestation: Planting new trees on land that was not previously forested, or where forests have been completely cleared, to create new forest cover.

(ii) Reforestation: Planting trees in areas where existing forests have been cut down or degraded, to restore the original forest ecosystem.

9. To set up a new industry, a large forest area had to be cut. List four ways in which the environment in that area may be affected.

Answer: Cutting down a large forest area to set up a new industry can affect the environment in the following ways:

(i) Destruction of habitat for wild plants and animals leading to loss and disappearance of many species leading to loss of biodiversity.

(ii) Reduced rainfall.

(iii) Lowering of water table affecting water cycle and resulting in drier climate.

(iv) Soil erosion, loss of fertility of soil and lack of vegetation leading to desertification.

(v) Increased levels in the atmosphere leading to global warming.

10. How does production of more paper in the world contribute to ecological imbalance? Use only four key phrases to support your answer.

Answer:  The production of more paper contributes to ecological imbalance through:

(i) Deforestation for raw materials

(ii) Loss of biodiversity and habitat destruction

(iii) High energy consumption and greenhouse gas emissions

(iv) Air and water pollution from manufacturing processes

11. What could be a major disadvantage for man being placed at the top of the food chain? Name the phenomenon that may cause this harmful effect.

Answer: The major disadvantage of man being at the top of the food chain is that harmful non-biodegradable chemicals accumulate in the body in high concentrations, which can cause serious health problems.

The phenomenon responsible for this is biomagnification.

12. List any three ways in which noise from various sources can affect the well- being of a person. Suggest few methods to control noise pollution.

Answer: Effects of noise pollution:

(i) Noise pollution can cause serious damage to ears leading to temporary loss of hearing, earache, sometimes even permanent deafness.

(ii) Noise prevents concentration, increases irritability and causes headache. It may lead to increased blood pressure and irregular heart beat.

(iii) Noise disturbs sleep and causes slow recovery from sickness.

Methods to control noise pollution:

(i) Keep the volume of your radio and television low

(ii) Use automobile horn only in case of emergency

(iii)  Avoid noisy fire crackers

(iv) Tune and service all machines including automobiles at regular intervals.

(v) Use of silencers should be mandatory.

(vi)  Plant trees, as a green belt around your home is an efficient noise absorber.

(vii) Report playing of loudspeakers during odd hours to the police immediately.

13. What does ‘Global warming’ mean? Name the gas responsible for this phenomenon and why should it be considered an environmental problem.

Answer: Global warming is the gradual increase in the average temperature of the Earth due to the enhanced greenhouse effect.

The main gas responsible for this phenomenon is carbon dioxide (CO₂).

It is considered an environmental problem because it :

(i)  changes the Earth's climate.

(ii) causes melting of glaciers and polar ice caps.

(iii) leads to a rise in sea level, causing floods in coastal areas.

(iv) disturbs ecosystems and agriculture.

14. It was observed that a large number of vultures were dying around a crop field. Considering the fact that vultures are top consumers, explain the phenomenon that may have caused their death in large numbers.

Answer: The phenomenon is biological magnification (biomagnification). As vultures are top consumers, they accumulate the highest concentration of non-biodegradable pesticides (like DDT) from the crop field through the food chain, leading to their death .

15. List and classify the waste generated at home? What is the difference between the different ‘groups’? How would you manage this waste so that it causes least pollution?

Answer: Household waste is mainly of two types:

(a) Biodegradable waste: Vegetable and fruit peels, leftover food, paper, leaves, etc.

(b) Non-biodegradable waste: Plastics, glass, metals, rubber, polythene, etc.

The difference between the two groups:

Biodegradable Waste	Non-biodegradable Waste
Can be broken down by microorganisms (bacteria/fungi) into simpler, harmless substances.	Cannot be broken down by microorganisms; persist in the environment for hundreds of years.
Decomposes naturally and returns to the soil as nutrients (compost).	Does not decompose; accumulates in landfills and causes pollution.
Does not cause long-term environmental harm if managed properly.	Causes land, water and air pollution; may lead to biomagnification.
Examples: food waste, paper, garden waste.	Examples: plastics, glass, metals, e-waste.

Management of household waste:

(i) Segregation at source: Separate biodegradable and non-biodegradable waste into different bins at home.

(ii) Composting: Convert kitchen and garden waste into compost (manure) for plants, reducing landfill burden.

(iii) Recycling: Send plastic, glass, and metal waste to recycling centres instead of dumping.

(iv) Reuse: Reuse plastic containers, glass jars and paper bags whenever possible.

(v) Reduce: Minimize the use of single-use plastics and non-essential packaging.

(vi) Avoid burning waste: Burning releases toxic fumes; instead, use scientific disposal methods.

16. Name the instrument used to measure the magnitude of an earthquake. Suggest any one of preventing way with them in earthquake prone areas.

Answer: The instrument used to measure the magnitude of an earthquake is a seismograph .

For prevention in earthquake-prone areas, a key measure is to construct earthquake-resistant buildings. This involves designing structures that can withstand tremors by keeping the design simple, using light construction materials like mud or timber and fixing heavy objects to walls to prevent them from falling. Consulting qualified architects and structural engineers is also crucial

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