Class 12 NIOS Biology Intext Solutions Chapter 27
INTEXT QUESTIONS 27.1
1. Define pollution.
Ans: Pollution is the 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 pollution, 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).
INTEXT QUESTIONS 27.2
1. Give two examples of natural sources of water pollution.
Ans: Soil erosion/leaking of minerals from rock/decay of organic matter (any two)
2. What is biomagnification?
Ans: Entry of harmful non-biodegradable chemicals in small concentrations and their accumulation in greater concentrations in the various levels of food chain is called biomagnification.
3. Give the technical term for the 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 .
(iii) Nickel
Ans:
- (i) Lead: Industrial waste. Nervous disorders, Kidney failure, and blood poisoning
- (ii) Tin: Industrial dust. Affects the central nervous system (CNS), and vision
- (iii) Nickel: Aerosols or industrial dust. Pulmonary disorders, dermatitis
INTEXT QUESTIONS 27.3
1. What is soil erosion?
Ans: The process of detaching and removal of loosened soil particles by water (running water, ground water, rain, sea waves) and wind is known as soil erosion.
2. Name the various types of soil erosion.
Ans: Wind erosion, sheet erosion, and Gully erosion.
3. Name any two natural factors responsible for soil erosion.
Ans: Wind, water
4. How does terracing prevent soil erosion?
Ans: Dividing a slope into several flat fields to control the rapid run of water. It is practiced mostly in hilly areas. 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.
INTEXT QUESTIONS 27.4
1. Name any two biodegradable pollutants.
Ans: Sewage, kitchen, waste, certain agricultural waste, hay, dung etc. (any two)
2. Mention two sources of noise pollution.
Ans: loudspeakers/sound of automobiles/sound from heavy machines/fireworks (any two)
3. Name any two greenhouse gases.
Ans: Nitrogen oxides, methane, carbon dioxide, chlorofluorocarbons. (any two)
4. What is acid rain?
Ans: When harmful gases like SO2 and NO2 in the atmosphere dissolve in water to form acid during rain, it is called acid rain.
INTEXT QUESTIONS 27.5
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: 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 radiation.
Ans: (i) cancer (ii) gene mutations.
