Natural Resources Test - 20

Ozone is a deadly poison and if all the oxygen were to get converted to ozone, no life on the earth would survive.

Solution

Correct answer is option C
Explanation for correct option:

• Discharge of untreated sewage, surface run-off water from agricultural fields and industrial wastes lead to eutrophication and explosive growth of planktons and blue-green alga.
• This increases turbidity and reduces levels of dissolved oxygen, thus killing aquatic animals.

• In watery regions, forests regulate the water cycle (hydrological cycle).
• The water cycle, also known as the hydrological cycle or the H$$_2$$O cycle, describes the continuous movement of water on, above, and below the surface of the Earth. 
• The water cycle involves the exchange of energy, which leads to temperature changes. 
• For instance, when water evaporates, it takes up energy from its surroundings and cools the environment. When it condenses, it releases energy and warms the environment. 
• The heat exchange regulates the climate.
• Forests help control the water cycle by regulating precipitation, evaporation, and flows.
  

Nitrogen fixation is a biological process in which nitrogen molecules present in the air are converted into nitrates and nitrites by nitrogen-fixing bacteria present in the soil. Nitrogen is an inert gas and is not accessible to plants. However, nitrates and nitrites are easily accessible to plants due to the presence of nitrogen-fixing bacteria that are either free-living or form a symbiotic association with plants.  

Correct Option - A

Explanation For Correct Option -

• Soil erosion can be effectively prevented by methods like afforestation and reforestation.
• Reforestation is the restoration of forests, which have been earlier destroyed by deforestation or other means, while afforestation is the raising of new forests.
• Plants hold the soil with their roots and thus prevent the soil from any erosion.

Explanation For Incorrect Options –

(B) Deforestation leads to an increase in soil erosion due to the decrease in the number of roots to hold the soil.
(C) Excessive use of fertilisers have deteriorating effects.
(D) Overgrazing leads to less grass cover so more soil erosion.

Vegetation cover on the ground helps to hold the soil in place. It also helps in percolating water into the deeper layers of the soil. The absence of vegetational cover may lead to soil erosion.

Correct option: C

Rain, wind, ice and temperature changes break the tough, hard parent material or rocks. This process is very slow but it steadily continues. Such broken parts are further withered by same factors as well as some other factors as acids etc. Therefore, wind, water and the Sun are involved in soil formation. 

Polythene bags are not involved in soil formation. However, plastic bags are threat to environment, because these bags are non-degradable, i.e., do not decay and thus, do not lead to soil formation.

Carbon-cycle is a process in which the carbon is circulated, transformed between living things and the environment. The burning of fossil fuels and respiration expels carbon dioxide in the environment which is fixed by the process of photosynthesis.
Transpiration is a process in which the moisture is carried from roots to the leaves and then evaporation occurs from the pores present on the underside of the leaves. Therefore, the correct answer is option B. 

• Groundwater is a natural resource of water that is prone to contamination due to increasing industrialization. 
• Human activities like waste disposal-private sewage disposal systems, land disposal of solid waste, municipal wastewater, industrial effluents, mine wastes, certain agricultural activities like the use of pesticides and chemical fertilizers, mining, acid rain, improper good construction, and maintenance, road salt contributes to contamination of groundwater. 
• Thus, the correct answer is option B.