NEET Biology Class 9 Chapter 6 Natural Resources Short Question And Answers

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Natural Resources Short Answer Questions

Directions: Give an answer in 2-3 sentences.

Question 1. Summarize the major types of global change caused by humans.
Answer: Major types of global change caused by humans include land and water transformation, changes to the chemistry of the earth (for example, changes to nutrient cycles), increases in biological invasions, and increases in the extinction rate of species.

Read And Learn More: NEET Class 9 Biology Short Question And Answers

Question 2. What roles do microorganisms play in the carbon and nitrogen cycles?
Answer: Carbon accumulates in wood. Microorganisms and fungi break down wood and return carbon to the biogeochemical cycles. If these organisms become absent, carbon would accumulate in the wood, where it could not be recycled into the environment. The function of nitrogen is dependent on microorganisms mostly.

3. State two harmful effects of Ozone hole or Ozone layer depletion.
Answer:

  1. Ozone layer depletion allows harmful ultra-violet radiations to reach the earth’s surface that may cause skin cancer and cataracts.
  2. UV rays also ionize the cells and change the gene structure in animals and plants.

Question 4. How can lichen help in indicating the pollutants in the air?
Answer:

Lichens are very sensitive to the levels of contaminants like sulphur dioxide in the air. Lichens generally grow on the bark of the trees. The trees on the road-side do not show this lichen growth, if in any area the growth of lichens decreases or vanishes the air will be polluted

Question 5. Why is Earth a unique planet on which life exists?
Answer:

Life exists on earth because many factors are responsible for the life to sustain.

  1. Ambient temperature
  2. Atmosphere
  3. Water

Question 6. How do fossil fuels cause air pollution?
Answer: Fossil fuels, like coal and petroleum, contain small amounts of nitrogen and sulphur. When these fuels are burnt, nitrogen and sulphur are also burnt and produce the oxides of nitrogen and sulphur, which pollute air. The combustion of fossil fuels also increases the amount of suspended particles in air which leads to air-pollution

Question 7. What is acid rain? Give its harmful effects.
Answer: The gases released due to the combustion of fossil fuels are SO2 , NO2, andCO2, these gases remain suspended in the air.

When it rains the rain water mixes with these gases to form sulphuric acid, nitrous acid, and carbonic acid and comes down on the surface of the earth in the form of acid rain.

Harmful effects of acid rain:

  1. It corrodes statues, monuments of marble, buildings etc.
  2. It makes the soil acidic.
  3. It damages crops, plantations

Question 8. Explain the importance of ozone to mankind.
Answer:

  • Ozone (O3) is a molecule of oxygen with 3 atoms of oxygen. It covers the earth’s atmosphere and is present in the stratosphere. It does not allow the harmful ultra-violet radiation coming from the sun to enter our earth.
  • These ultraviolet radiations cause an ionizing effect and can cause cancer and genetic disorders in any life form. The ozone is getting depleted at the south pole near Antarctica.
  • The ozone depletion is due to the halogens like CFC (chloroform carbon) released in the air. Chlorine fluorine reacts with the ozone and splits it, thereby leading to the formation of a big hole called an ozone hole.

Question 9. How does oxygen occur in nature? Explain the oxygen cycle in nature.
Answer:

  • Oxygen exists in two different forms in nature.
  • These forms occur as oxygen gas 21% and combined form in the form of oxides of metals and non-metals, in the earth’s crust, atmosphere and water. It is also present in carbohydrates, fats, and proteins.

Oxygen cycle, Oxygen from the atmosphere is used up in three processes, namely combustion, respiration and the formation of oxides of nitrogen. Oxygen is returned to the atmosphere by a process called photosynthesis.

Question 10. What is air pollution? How is it caused? Give its 2 harmful effects.
Answer:

The contamination of air with unwanted gases, particles like dust etc. which makes it unfit for inhalation is called air pollution

Causes :

  1. Burning of fossil fuels releases SO2 , CO2, and NO2 gases, causing acid rain.
  2. Burning of fuels releases unburnt carbon particles, and smoke.
  3. Smoke from industries

Harmful effects :

  1. It causes respiratory problems.
  2. Diseases like allergies, asthma, cancer and heart disease are caused.

Question 11. Name respiratory diseases that may occur due to air pollution.
Answer: Bronchitis, asthma, lung cancer, tuberculosis.

Question 12. List the main sources of water pollutants.
Answer:

  1. Sewage
  2. Industrial wastes
  3. Synthetic soaps and detergents
  4. Fertilizers and pesticides
  5. Petroleum oil
  6. Heat

Question 13. What are inexhaustible resources? Give examples.
Answer: These are present in unlimited quantity in nature and are not likely to be exhausted by human use, for example, air, and solar energy.

Question 14. Give two ways in which carbon dioxide is found.
Answer:

  1. Green plants, through photosynthesis, convert CO2 to glucose in the presence of sunlight.
  2. Many marine animals use carbonates dissolved in sea water to form their shells.

Question 15. What are non-biodegradable substances?
Answer:

There are substances which can not be broken down by the activity of micro-organisms. These go on concentrating trophic levels of the food chain, e.g., DDT, heavy metals (mercury, cadmium etc.)

Question 16. Name two types of biogeochemical cycles.
Answer: Gaseous cycles and sedimentary cycles

Question 17. Differentiate between humification and mineralization.
Answer: Humiliation is the process by which simplified detritus gets converted into dark-coloured amorphous substance humus in the soil.

Question 18. What do you mean by hygroscopic water and combined water in the soil? Are these available to plants?
Answer:

Some water in the soil forms an extremely thin, tightly held firm around the soil particles. It is called hygroscopic water. In the soil, a small portion of soil water is chemically bound with soil materials. It is called combined water. Both these types of water in the soil are not available to plants for absorption by their roots.

Question 19. Name two freshwater sources that provide fresh water for human use.
Answer:

  1. Groundwater.
  2. Surface water (ponds, lakes, streams rivers etc.)

Question 20. List two bacteria that bring about nitrification.

  1. List one denitrifying bacteria.
  2. List any two bacteria that play a role in biological nitrogen fixation.

Answer:

  1.  Nitrobacter, Nitrocystis.
  2. Pseudomonas.
  3. Azotobacter, Rhizobium leguminosarum

Question 21.  List at least three gaseous air pollutants that are emitted from automobiles and industries. Also their harmful effects on the health of human beings.

Answer:

  1. Three common gaseous pollutants are sulphur dioxide (SO2), oxides of nitrogen (NOx) and carbon monoxide (CO).
  2. When SO2 and (and NOx) are inhaled, these may cause bronchitis, asthma and lung cancer. Carbon monoxide inhalation may result in carbon monoxide poisoning

Question 22. Mention any three human activities that are responsible for the depletion of the ozone layer.
Answer:

The human activities responsible for the depletion of the ozone layer are :

  1. Excessive use of chlorofluorocarbons (CFCs)
  2. Nuclear testing
  3. Excessive use of nitrogenous fertilisers

Question 23. Name two diseases caused by

  1. Infectious agents in polluted water.
  2. Toxic chemicals in polluted water.

Answer:

  1. Diseases caused by infectious agents in polluted water are cholera and typhoid.
  2. Diseases caused by toxic chemicals in polluted water are cancer and arsenicosis

Question 24. Why are chlorofluorocarbons supposed to be responsible for the depletion of the ozone layer? Explain.
Answer: Chlorofluorocarbons are inert, highly stable, colourless and odourless chemicals extensively used in refrigerators and air conditioners.

  • Chlorofluorocarbons are nontoxic in the troposphere, but they slowly diffuse into the stratosphere where, under the influence of high-energy radiation, they break to produce chlorine atoms.
  • Chlorine atoms react with ozone in the stratosphere to produce chlorine monoxide and O2. Chlorine monoxide reacts with atomic oxygen to regenerate chlorine. A single chlorine atom can destroy about 1,00,000 ozone molecules

Question 25. How do organisms help in soil formation?
Answer: Soil formation occurs in steps. due to weathering, parent rocks break into gravel sand, silt and clay, which become habitats for a large variety or organisms like algae, fungi, helminths, insects, frogs, reptiles, rodents, etc. Death and decay of these living forms provide organic matter which combines with inorganic matter derived from the parent rock to form humus, which finally develops into mature soil.

Question 26. What will happen if nitrogen fixation does not take place?
Answer: The majority of organisms will not be able to use atmospheric nitrogen directly. Through the process of fiation, free nitrogen is converted into ammonia and nitrate, which is taken up by plants to be converted into amino acids, nucleotides, proteins and other nitrogenous compounds. In the absence of the nitrogen fixation process, these substances, which are necessary for the structural and functional growth of organisms, will not be formed.

Question 27. How can we prevent the loss of topsoil?
Answer: The upper A-horizon of soil is called top soil. It contains most of the litter, humus and roots of small plants embedded in it.

Question Loss of top soil can be prevented by the following ways :

  1. By preventing deforestation
  2. By preventing excessive grazing of grasses and small plants by herbivores.
  3. By preventing plantation and increasing the vegetational cover

28. All living organisms are basically made up of C, N, S, P, H and O. How do they enter the living forms? Discuss.
Answer: The substances like C, N, S, P, H and O enter the living body through biogeochemical cycles. The atmospheric carbon (CO2) is used by plants during photosynthesis to synthesise carbohydrates.

  • When animals feed upon the plant products, carbon enters into the animal’s body. Phosphorus and sulphur are absorbed by plants from the soil.
  • Animals obtain it through food and water. Oxygen enters into plants’ and animals’ bodies through the process of respiration.
  • Hydrogen enters into plant bodies through absorbed water and into animals’ bodies through food and water. Plants absorb nitrogen from soil as nitrates and nitrites and convert them into proteins. When these plants are eaten by animals, nitrogen enters into the animal’s body

Question 29. Why are root nodules useful for the plants?
Answer:

The roots of leguminous plants bear nodules. Nitrogen bacteria, Rhizobium reside inside these modules. Rhizobium can directly utilise atmospheric nitrogen and convert it into nitrogenous compounds like ammonia and nitrates. In this way plants get easy access to these chemicals which are good for plant growth. This is the reason that root nodules are useful for plants

Question 30. Why does water need conversation even though large oceans surround the land masses?
Answer: Water constitutes more than 70% of the total earth’s surface. Out of the total water resources only 2.7%, which is fresh water, is used by human beings for themselves or for agriculture and animal husbandry. Marine water is not uniformly available over the different parts of the earth.

Even at a particular place the demand and availability of fresh water differs according to season and climate. The demand for fresh water is likely to increase with the rising population, so it is essential to conserve this natural resource through proper management.

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