Chapter 30 Human Impact on Environment Textbook Solutions

NIOS Class 10 Science Chapter 30 Question Answers

INTEXT QUESTIONS 30.1

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

Ans: An environmental problem caused by natural factors and not by humans.

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.

Ans: Creep under the bed or table; cover your head with your arms/pillow/any other protective material.

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

Ans: 

• (a) Cause of Forest fires :
  • Lightning striking dry grass/trees
  • Heat is generated in the litter in the dry season
  • Human negligence
• (b) Landslide: Heavy / prolonged rainfall / deforestation / dynamite blasting
• (c) Flood — inadequate capacity within the banks of the river to mountain the light flora of water during 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.

Ans: By issuing early warnings of such natural disasters/plans to tackle such disasters.

5. What happens after a cloudburst?

Ans: Extreme amount of precipitation along with thunderstorm/hailstorm; flash flood causes loss of lives and property.

INTEXT QUESTIONS 30.2

Fill in the blanks.

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

Ans: Cheetah, Tiger

2. Need for ___________ leads to felling of trees.

Ans: Housing, construction of roads, industrialization (any one)

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

Ans: Silviculture, mass plantation

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

Ans: Air pollution, water pollution, global warming (any two)

INTEXT QUESTIONS 30.3

Fill in the blanks.

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

Ans: Excreta (Animal/Human) and agricultural water.

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

Ans: Fish

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

Ans: Human and animal excreta.

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

Ans: Eutrophication

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

Ans: DDT

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

Ans: Plastic bags/kitchen waste/glass bottles, etc. (any two)

7. Unwanted sound may lead to_____________ pollution.

Ans: Noise pollution

8. Noise pollution may be caused by___________ and __________.

Ans: Vehicles/loudspeakers/loud volume of TV, music system/fireworks.

TERMINAL EXERCISES

1. Choose the correct option

(i) Growing trees for afforestation is called

a) Monoculture 

b) horticulture

c) Silviculture 

d) Agriculture

Ans: c) Silviculture 

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

a) Carbon dioxide 

b) Chloro-fluorocarbons

c) Nitrogen 

d) Water vapour

Ans: b) Chloro-fluorocarbons

(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

Ans: c) DDT 

(iv) Soil erosion can be prevented by

a) Use of pesticides 

b) deforestation

c) Afforestation 

d) excessive use of fertilizers

Ans: c) Afforestation 

2. Which of the following are biodegradable?

Aluminum foil, paper, ballpoint pen refill, grass

Ans: Paper and grass. 

3. Which gaseous pollutant has the ability to absorb infrared radiation?

Ans: Carbon dioxide. 

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?

Ans: Eutrophication. The enrichment of water with nutrients such as nitrates and phosphates that triggers the growth of green algae is called eutrophication.

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

Ans: Refrigerators and air conditioners produce chemicals called chloroflurocarbons or CFCs that damage ozone layer. This is why they are not eco-friendly. 

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.

Ans: Leakage from oil ships causes petroleum to spread in the ocean, leading to the death of marine life due to the non-availability of dissolved oxygen. 

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

Ans: Silviculture. 

8. List two ways of replenishing forests.

Ans: 

• Growing of more plants to substitute for every single tree that has been cut.
• Practising silviculture, the cultivation of forest trees, provides wood for industries and also increases the area under the forest cover.

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.

Ans: Cutting down of forests may result in the following:

• Destruction of habitat for wild plants and animals leads to the loss and disappearance of many species, leading to the loss of biodiversity.
• Reduced rainfall
• Lowering of the water table affects the water cycle and results in a drier climate
• Soil erosion, loss of soil fertility, and lack of vegetation leading to desertification
• Increased CO2 levels in the atmosphere are 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.

Ans: 

• Global warming
• Soil erosion
• Reduced rainfall
• Deforestation

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.

Ans: The major disadvantage of being at the top of the food chain is accumulating high concentrations of toxic chemicals in the body, leading to health problems. This phenomenon is called biomagnification, where harmful, non-degradable substances like pesticides become more concentrated as they move up each trophic level in a food chain.

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.

Ans: Effects of noise pollution

• Noise pollution can cause serious damage to the ears, leading to temporary loss of hearing, earache, and sometimes even permanent deafness.
• Noise prevents concentration, increases irritability, and causes headaches. It may lead to increased blood pressure and irregular heartbeat
• Ringing of ears (a feeling of sound coming from within the ear in a very quiet environment) is also a result of noise pollution
• Noise disturbs sleep and causes slow recovery from sickness.

The following steps can be taken to control or minimize noise pollution:

• Keep the volume of your radio and television low
• Use the automobile horn only in case of an emergency
• Avoid noisy firecrackers
• Tune and service all machines, including automobiles, at regular intervals. Use of silencers should be mandatory.
• Planting trees as a green belt around your home is an efficient noise absorber.
• Report the laying 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?

Ans: The increase in Earth’s average temperature is increasing each year, leading to global warming. The gas responsible for this phenomenon is carbon dioxide. Heat contained in the solar radiation is allowed to come in, but the heat contained in it is not sent back due to the increasing concentration of CO2 and other greenhouse gases.

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.

Ans: The phenomenon that may have caused their death in large numbers is called eutrophication. The enrichment of water with nutrients such as nitrates and phosphates that triggers the growth of green algae is called eutrophication.

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?

Ans: Waste can be classified into biodegradable (e.g. cattle dung, vegetable peels, paper, wood, etc.) and non-biodegradable (e.g. aluminium cans, glass bottles, plastics, DDT, etc.).

• Biodegradable waste includes substances that can be degraded by microbes into harmless and non-toxic substances. Agricultural and animal wastes like leaves, twigs, hay, dung, etc., are biodegradable wastes.
• Non-biodegradable waste cannot be easily degraded. Aluminum cans, plastics, glass, electronic waste, batteries, etc., are examples of non-biodegradable wastes.

Reduce, Reuse, Repair, and Recycle should be our guiding principles for reducing waste generation. Recycling of plastics and paper, converting municipal waste into manure, and rice husk into wood particle board are some such examples. Use of cattle dung for the production of biogas is also good example of recycling of waste for the production of energy.

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

Ans: Seismograph. In the event of an earthquake, stay as safe as possible. Minimize your movements to a few steps to a nearby safe place and stay indoors until the shaking has stopped and you are sure exiting is safe.

Additional Study Materials

• Chapter 25 Heredity
• Chapter 26 Air and Water
• Chapter 29 Natural Environment