Question 1

Why is water essential for life?

Accepted Answer

Explanation-Water is essential for life because: Water forms the major component of a living organism. It plays a vital role as all the metabolic processes required for growth and development requires a liquid medium.Most of the reactions occur when the substances are in the dissolved state. Water also helps in the transportation of these dissolved substances in the body. Water helps in maintaining the body temperature.

Question 2

Forests are called the lungs of the earth. Why?

Accepted Answer

Forests are called lungs of the earth because they absorb an enormous amount of carbon dioxide that circulate in the atmosphere. They are effective and thus protecting those lungs is crucial if we are to defend the plant biodiversity and fight global warming.

Question 3

Which of the following statements is not correct? (i) Forests protect the soil from erosion. (ii) Plants and animals in a forest are not dependent on one another. (iii) Forests influence the climate and water cycle. (iv) Soil helps forests to grow and regenerate.

Accepted Answer

Plants and animals in a forest are not dependent on one another, this is the wrong statement among the given options. They should depend on each other for survival, because each provides something the other needs. This dependency can be well illustrated with the help of food chain in the ecosystem.

Question 4

What is the percentage of earth surface which is covered by water?

Accepted Answer

About 71 % of the Earth's surface is water-covered, and the oceans hold about 96.5 % of all Earth's water. Water also exists in the air as water vapor, in rivers and lakes, in icecaps and glaciers, in the ground as soil moisture and in aquifers.So, the correct answer is option C.

Question 5

Which of the following is a source of fresh water?

Accepted Answer

The rainwater, groundwater and surface runoff are the sources of freshwater.Freshwater is naturally occurring water on Earth's surface in ice sheets, ice caps, glaciers, icebergs, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams.Thus all three of the options are correct.

Question 6

Over exploitation of natural resources causes ........................ problems

Accepted Answer

Overexploitation of natural resources by humans has caused many negative impacts on the environment. Natural resources like coal, petrol, natural gas are limited and their excess use will lead to their depletion. Once used, these resources are lost forever as they are non-renewable. Overexploitation of natural resources like forests has resulted in deforestation and this will lead to habitat loss of many species of animals and microorganisms. Climate change and global warming are other harmful impacts of overexploitation of natural resources.So, the correct answer is 'environmental problems'

Question 7

Rain is the ultimate source of water.

Accepted Answer

The ultimate source of water is the water bodies which are present on earth which includes large oceans, seas, rivers, etc. Rain is only the way of water returning to their sources which they have lost by evaporation.This rain is not an ultimate source of water .the ultimate source are the water bodies present on earth example large oceans, rivers etcSo, the correct answer is 'False'.

Question 8

Which one of the following is not responsible for water shortage ?

Accepted Answer

Water is one of the most valuable resources on Earth. Rainwater fills reservoirs that supply drinking water, provide a habitat for fish to live, and nourishes the soil with water necessary for vegetation.Hence Heavy rainfall is not responsible for water shortage.So, the correct answer is 'Heavy rainfall'.

Question 9

What is the main cause of extinction of wild life?

Accepted Answer

Wildlife species may become totally extinct if no measures are taken to protect them. Some of the reasons for the extinction of wildlife are-a) Destruction of their natural habitats by environmental pollution, deforestation, soil erosion, overgrazing, increased urbanization, forest fires, and developmental works.b) Indiscriminate huntingExample: Cheetah is extinct in Indiac) Introduction of exotic species.d) Overexploitation of natural resources.e) Disturbance in migratory routes.f) International trade in rare animals.g) Lack of education.So, the correct answer is option D.

Question 10

Which of the following can be recycled?

Accepted Answer

Almost all kinds of paper are recyclable. Newspaper, envelopes, textbooks, notebooks, drawing sheets, card board, etc., all can be recycled.