Natural Resources Class 9 Worksheet Science

Q.1. Fill in the blanks

(i) Things essential for life that are provided by nature are known as Natural resources.

(ii) Sea breeze is the movement of a wind from land to sea.

(iii) All cellular processes need Aqueous or water medium to occur.

(iv) Soil is produced due to breaking of rocks at or near the surface of earth due to various factors.

(v) Washing away of soil particles and exposure of underneath rocks is known as Soil erosion.

Q.2. One of the following factors does not lead to soil formation in nature
(a) The sun
(b) Water
(c) Wind
(d) Polythene bags

Correct Answer is Option (d)

Q.3. Total earth’s surface covered by water is
(a) 75%
(b) 60%
(c) 85%
(d) 50%

Correct Answer is Option (a)

Q.4. The fertility of soil is lost due to
(a) Afforestation
(b) crop rotation
(c) Soil erosion
(d) strip cropping

Correct Answer is Option (c)

Q.5. Which substance is responsible for depletion of ozone layer?
(a) CO₂
(b) CH₄
(c) CFC’S
(d) CO

Correct Answer is Option (c)

Q.6. The major component of air in Venus & Mars is –
(a) O₂
(b) CO₂
(c) NO₂
(d) He

Correct Answer is Option (b)

Q.7. What is the greenhouse effect?

Due to trapping of radiations by green house gases like carbon dioxide, methane etc results into increase in the global temperature excess of which leads to global warming and the phenomenon that cause it is named green house effect.

Q.8. Why do organisms need water?

• All organisms are made up of cells. All cellular processes take place in a water medium. All the reactions that take place within our body and within the cells occur between substances that are dissolved in water.

• Substances are also transported from one part of the body to the other in a dissolved form. Hence, organisms need to maintain the level of water within their bodies in order to stay alive.

Q.9. What are the different types of natural resources? Give examples.

Natural resources are of two types:

• Inexhaustible natural resources: Those resources that are present in unlimited quantity in nature and are not likely to be exhausted by human activities, for example air, water, solar energy.
• Exhaustible natural resource: These resources are present in limited quantity in nature and these are likely to be exhausted by human activities for example coal, petroleum, minerals.

Q.10. Mention two causes of over-exploitation of natural resources.

Causes of over exploitation of natural resources are:

• Tremendous population increase
• Industrial and technological progress which has increased the rate at which these resources are being used.
• Rapid urbanization.

Q.11. What is biological nitrogen fixation? Name the organisms responsible for it.

It is a process in which atmospheric nitrogen is converted into usable or soluble form by micro-organism. Microbes responsible nitrogen fixation are – Rhizobium, Azotobacter, Blue green algae, etc.

Q.12. What causes winds?

When air is heated by radiation from the heated land or water, it rises. But since land gets heated faster than water, the air over land would also be heated faster than the air over water bodies. Therefore, during the day, the air above the land gets heated faster and starts rising. As this air rises, a region of low pressure is created and air over the sea moves into this area of low pressure. The movement of air(wind) from one region to the other creates winds.

Q.13. How is soil formed?

Over long periods of time, thousands and millions of years, the rocks at or near the surface of the Earth are broken down by various physical, chemical and some biological processes. The end product of this breaking down is the fine particles of soil.

Factors responsible are as follows:

• The Sun: The Sun heats up rocks during the day so that they expand. At night, these rocks cool down and contract. Result is formation of cracks.
• Water: Water helps in the formation of soil in two ways. One, water could get into the cracks in the rocks formed due to uneven heating by the Sun. If this water later freezes, it would cause the cracks to widen.
• Wind: In a process similar to the way in which water rubs against rocks and wears them down, strong winds also erode rocks down.
• Living organisms: The lichen grows on the surface of rocks. While growing, they release certain substances that cause the rock surface to powder down and form a thin layer of soil. Other small plants like moss, are able to grow on this surface now and they cause the rock to break up further. The roots of big trees sometimes go into cracks in the rocks and as the roots grow bigger, the crack is forced bigger.

Q.14. Why is water essential for life?

Water essential for life because:

• All organisms are made up of cells. All cellular processes take place in a water medium. All the reactions that take place within our body and within the cells occur between substances that are dissolved in water.
• Substances are also transported from one part of the body to the other in a dissolved form.
• Essential for digestion.
• Helpful in excretion and egestion.
• Regulates our body temperature by sweating and evaporation.

Q.15. Mention human activities that lead to air pollution.

Sources of air pollution are:

• Forest fires, smoking volcanoes dust storms, pollen grains floating in air and decay of organic natter
• Over – population, deforestation, urbanization, and industrialization.
• Burning of fossil fuels in automobiles, thermal power plants and industries.

Q.16. How is rain formed?

Water from water bodies gets evaporated and water vapours are formed. These water vapours then move up the atmosphere and condense into small water droplets. As many water droplets combine, bigger water droplets are formed, as they grow heavy and big, the fall down in the form of rain.

Q.17. How is soil pollution done?

Soil pollution happens in following ways:

• Use of large amounts of fertilizers and pesticide kills the microorganisms that help in recycling of nutrients in soil.
• Earthworms are also killed by pesticide which enriches the soil by making humus.
• Useful components get removed and other harmful substances get added which affect the fertility of soil.

Q.18. How do forests influence our air, water and soil?

• Forest act as purifier of air, They utilize carbon – dioxide and release oxygen, in the process of photosynthesis.
• Forest also maintain level of water under the soil Roots of trees absorbs water and increase water level.
  Trees also help in the formation of clouds by the process of transpiration and increases humidity (water vapour) in the air. This water vapour further forms clouds and helps in rain.
• Roots of trees hold the soil and prevent soil erosion. This maintains the fertility of the soil.

Q.19. What is weathering? What are the different means by which weathering occurs.

Formation of soil due to breakdown of rocks is known as weathering.

It occurs by:

• Physical means: such as the sun (temperature), rain, wind, frost.
• Biological means: Through the action of plants, animals and micro-organisms.

Q.20. Why is life possible on earth?

Life is possible on earth because of the following reasons:

• The temperature on earth is suitable for different life forms.
• The presence of oxygen in air which is required by all living organisms.