NIOS Class 12 Biology Chapter 27 Pollution

NIOS Class 12 Biology Chapter 27 Pollution Solutions to each chapter is provided in the list so that you can easily browse throughout different chapters NIOS Class 12 Biology Chapter 27 Pollution Notes and select need one. NIOS Class 12 Biology Chapter 27 Pollution Question Answers Download PDF. NIOS Study Material of Class 12 Biology Notes Paper 314.

NIOS Class 12 Biology Chapter 27 Pollution

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Also, you can read the NIOS book online in these sections Solutions by Expert Teachers as per National Institute of Open Schooling (NIOS) Book guidelines. These solutions are part of NIOS All Subject Solutions. Here we have given NIOS Class 12 Biology Chapter 27 Pollution Solutions, NIOS Senior Secondary Course Biology Solutions for All Chapter, You can practice these here.


Chapter: 27




1. Define pollution.

Ans: It is defined as “the addition unwanted substances to the environment which have adverse effects on organisms”.

2. Name four types of pollution.

Ans: For types of pollution are:

(i) Air pollution.

(ii) water pollution.

(ii) land pollution.

(iv) noise pollution.

3. Name one effect on plants and one on human caused by excess SO₂ in the air.

Ans: (i) On humans: Respiratory problems.

(ii) On plants: Chlorosis (loss of chlorophyll in plants).


1. Give two examples of natural sources of water pollution.

Ans: (i) Soil erosion.

(ii) Leaking of mineral from rock.

2. What is biomagnification? 

Ans: It refers to “the accumulation in greater concentration of chemicals at higher levels of food chain”.

3. Give the technical term for enrichment of water bodies with nutrients coming from fields.

Ans: Eutrophication.

4. Give one source of and one disease caused by from the following pollutants:

(i) lead.

(ii) tin. and 

(iii) nickel.

Ans: Pollutant, Source and Disease:

(i) LeadIndustrial wasteKidney failure
(ii) TinIndustrial DustAffects CNS in humans.
(ii) NickelAerosolsRespiratory diseases


1. What is soil erosion?

Ans: Soil erosion is “the detachment and removal of soil particles by flowing water and blowing wind”.

2. Name the various types of soil erosion.

Ans: Wind erosion, sheet erosion, and gully erosion are three types of soil erosion.

3. Name any two natural factors responsible for soil erosion. 

Ans: (i) Wind. and 

(ii) water are two natural factors to cause soil erosion.

4. How does terracing prevent soil erosion?

Ans: Terracing: It is a method of farming to conserve thin soil layer on the slopes of moun-tains. It is most effective to grow crops on terraces.


1. Name any two biodegradable pollutants.

Ans: (i) Sewage.

(ii) Agricultural waste.

2. Mention two source of noise pollution.

Ans: (i) Loud speakers.

(ii) Sound from heavy machines.

3. Name any two green house gases.

Ans: (i) Methane (CH₄).

(ii) Chlorofluoro-carbons (CFCs).

4. What is acid rain?

Ans: When harmful gases such as SO₂ and NOₓ in atmosphere dissolve in water to make acid during rains.


1. Give one example each of natural and man made radiations.

Ans: (i) Natural = Solar radiations.

(ii) Man-made = Gamma rays.

2. List two wastes of atomic explosion. 

Ans: Two wastes of atomic explosion are:

(i) Radioactive Iodine.

(ii) Strontium.

3. Name the containers should be used for the disposal of nuclear wastes.

Ans: Lead containers.

4. List any two harmful effects of nuclear radiations.

Ans: (a) Gene mutation. and 

(ii) Cancer.


1. Which of the following are biodegradable materials?

Aluminium, wood, fruit peels, DDT, paper, glass, dung.

Ans: (i) Wood.

(ii) fruit peels.

(iii) paper.

(iv) dung.

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

Ans: Atmospheric gases like CO₂ and methane absorb major part of infra-red radiations.

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

Ans: This is a case of oil spill pollution. It would cause the death of aquatic marine organisms (serious consequences).

4. 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: Four ways in which the environment in that area will be affected are:

(i) The air will be polluted due to smoke released by the industry.

(ii) The quality of water of that area will be degraded.

(iii) Productivity by plants will be reduced.

(iv) The oxides of nitrogen from factories reduce the O₂ carrying capacity of blood in humans; may cause cancer and irritation of eyes.

5. 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: Noise Pollution: “The unwanted sound or the loud sound is called noise”. It is a way of alarming and communicating and recreating in animals and men. It is a physical type of pollution. It has direct effects on humans.

Effects of Noise Pollution:

(i) The main effect of the noise pollution is impairment of hearing.

(ii) Ear drum can burst due to loud sound. There may be some loss in hearing capacity. Some people become deaf in cities due to loud unwanted sound.

(iii) Sound pollution increases sleeplessness and heart beat rate, constriction of blood vessels and digestive spasm etc. Prolonged exposure to 80 decibel or more affects the loss in hearing capacity.

Methods to Control Noise Pollution:

(i) Proper lubrication and maintenance of machines can minimise noise.

(ii) Sound proofing of work places be done to control noise pollution.

(iii) Using protecting devices e.g., ear plugs.

(iv) Ban on use of loud speakers.

(v) Check on traffic in the residential colonies and areas.

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

Ans: Global Warming: The accumulation of high concentration of CO₂ has led to global warming/greenhouse effect. It has resulted in increased earth’s temperature.

It is considered an environmental problem because due to increase in temperature the ice caps and glaciers are melt and it caused the raise of seas and oceans. Consequently the coastal areas and islands will be submerged

Fig. 27.6. Greenhouse Effect.

7. How would you classify the waste generated at home? What is the difference between the different groups? How would you manage this waste so that it cause least pollution?

Ans: The waste generated at home fall into two groups:

(a) Biodegradable Waste: It includes the substances which can be degraded by microbes into harmless and non-toxic substances e.g., sewage, kitchen waste, agricultural and animal wastes (leaves twigs, hay, dung).

(b) Non-biodegradable Waste: This cannot be easily degraded e.g., aluminium cans, plastics, DDT, glass. These wastes may be reduced by burning/incineration and landfill. Some may be recycled to cause less pollution.

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