Pollution : 12th Class Biology Question Answer Lesson 27 – NIOS

Pollution : 12th Class Biology Question Answer Lesson 27 – NIOS

Pollution : 12th Class Biology Question Answer Lesson 27 - NIOS


  1. Define pollution.
    Ans. Addition of unwanted substances to the environment which have adverse
    effects on organisms.

  2. Name four types of pollution.
    Ans. Air pollution, water pollution, land polluton, noise pollution.
  3. Name one effect on plants and one on human caused by excess SO2 in the air.
    Ans. Respiratory problems in humans, chlorosis (loss of chlorophyll in plants).


  1. Give two examples of natural sources of water pollution.
    Ans. Soil erosion/leaking of mineral from rock/decay of organic matter.
  2. What is biomagnification?
    Ans. 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
    Ans. Source – Industrial waste
    Disease – Nervous disorders, Kidney failure, blood poisoning
    (ii) Tin
    Ans. Source -Industrial dust
    Disease – Affects central nervous system (CNS) Affects, vision
    (iii) Nickel
    Ans. Source – Aerosols, industrial dust
    Disease – Pulmonary disorders, dermatitis


  1. What is soil erosion?
    Ans. Detachment and removal of soil particle by flowing water and blowing

  2. Name the various types of soil erosion.
    Ans. Wind erosion, sheet erosiion, Gully erosion.
  3. Name any two natural factors responsible for soil erosion.
    Ans. Wind, water
  4. How does terracing prevent soil erosion?
    Ans. Terracing is a method of farming to conserve the thin soil layer on the mountain slopes. This helps in controlling soil erosion and using water resources of these areas more economically and effectively for growing crops on these terraces.


  1. Name any two biodegradable pollutants.
    Ans. Sewage, kitchen, waste, certain agricultural waste, hay, dung etc. (any
  2. Mention two source of noise pollution.
    Ans. loud speakers/sound of automobiles /sound from heavy machines/fire works (any two)
  3. Name any two green house gases.
    Ans. Nitrogren oxides, methane, carbon dioxide, chlorofluoro carbons. (any two)
  4. What is acid rain?
    Ans. When harmful gases like SO2 and NOx in the atmosphere dissolve in water
    to form acid during veins.


  1. Give one example each of natural and man made radiations
    Ans. Solar/cosmic (any one); x-ray/gamma rays (any one)
  2. List two wastes of atomic explosion.
    Ans. Radioactive Iodine and strontium
  3. Name the containers which should be used for the disposal of nuclear wastes.
    Ans. Lead containers
  4. List any two harmful effects of nuclear radiations.
    Ans. (i) cancer (ii) gene mutations.


  1. Which of the following are biodegradable materials?
    Aluminium, wood, fruit peels, DDT, paper, glass, dung
  2. Which gaseous pollutant has the ability to absorb infra-red radiations?
  3. A ship carrying oil from the gulf region collides with hug rocks and get damaged.
    It this just news or has some serious consequences? Give your opinion in one
  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.
  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.
  6. What does ‘Global warming’ mean ? Name the gas responsible for this
    phenomenon and why should it be considered an environmental problem.
  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?

NIOS 12th class biology Q Ans

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Himanshu Kumar

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