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Q1. Name fours segments of environment and explain them in brief.
Answer: The environment consists of four segments namely Biosphere, Lithosphere,
Hydrosphere and Atmosphere.
1. Biosphere: The environment which supports life and sustains various human
activities is known as biosphere.
2. Lithosphere: It is the outer mantle of the solid earth i.e. earth crust consisting of
rocks and soil. The soil is the most important part of lithosphere.
3. Hydrosphere: It includes all kinds of water resources, oceans, rivers, lakes, streams,
glaciers, polar ice caps and ground water.
4. Atmosphere: It is the protective blanket of gases surrounding the earth. The main
components of the atmosphere are nitrogen (78%), oxygen (20.95%) and minor
components are argon, hydrogen, ozone and other inert gases like helium and neon.
Q2. What are endangered species?
Answer: The species that are considered in imminent danger of extinction and whose
survival is unlikely if factors causing their decline continue to opearte i.e. these are the
species whose number has beenreduced to a critical level that they are in immediate
danger of extinction.
e.g. tiger, swamp, Pinkh duck etc.
Q3. What are the causes of soil pollution?
Answer: Soil pollution is resulted due to the human activities such as dumping of the
waste, use of agrochemicals, mining operations and urbanization. Many materials
adversely affect the physical, chemical and biological properties of soil and reduce its
productivity. These include:
1. Municipal, Industrial and Radioactive Waste
2. Discarded material
3. Pesticides, fertilizers and organic manures
4. Mining Operations
Q4. Differentiate between degradable and non- degradable pollutants.
Answer: Degradable pollutants can be decomposed, removed or reduced to acceptable
level either by natural or artificial means e.g. human sewage, animal and crop waste
Non-degradable pollutants cannot be degraded by natural or artificial means. They are
not recycled in the aqueous system naturally.
e.g. radioactive materials, heavy metals and plastics.
Q5. Mention the main cause of smog.
Answer: Some of the main causes and sources of smog are gasoline and diesel power
vehicles, factories, oil based paints, solvents and cleaners, pesticides and coal fired
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Q6. Distinguish between deforestation and desertification.
Answer: Deforestation is the permanent destruction of forest and their replacement for
Desertification is a process in which the productivity potential of arid and semi-arid lands
fall by 10% or more and then turn into non-productive land.
Q7. How can mineral resources be conserved?
Answer: Mineral resources can be conserved by:
1. Minimizing waste and developing the technologies to recover the resource from the
2. Developing the alloys that will reduce the demand of the pure metals.
3. Finding the alternative to the fossil fuels.
4. Discovering the new mining areas.
Q8. Discuss in brief the greenhouse effect.
Answer: The greenhouse gases in the lower levels of the atmosphere, like glass are
transparent to the near infra-red rays of shorter wavelength but are opaque to the heat
radiated by the heated earth (longer wavelength heat ray) and trap them. By not letting
the solar rays to escape into the outer space, greenhouse gases add to the heat that is
already present on the earth surface. This results in increase in temperature and is
commonly known as Greenhouse effect.
The major sources of greenhouse gases are: carbon dioxide, methane,
chlorofluorocarbons, nitrous oxide etc.
Q9. Name the plant which yield drug for malaria and cancer?
Answer: Quinine is a drug for malaria which is made from the bark of cinchona tree.
For cancer, Camptothea Acuminata plant is a member of Tupelo family which is only
present in China and Tibet. Its anti-cancer ingredient is Quinoline alkaloid, which in turn
has been modified to create a host of other anti-cancer drugs.