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Question : 2
Total: 6
(a) State with reason the consequence of decrease in number of carnivores in an ecosystem.
(b) In a food chain, state the trophic level at which the concentration of harmful chemicals is maximum. Why is it so ?
OR
How is ozone layer formed? State its importance to all life forms on earth? Why the amount of ozone in the atmosphere dropped sharply in the 1980 s?
(b) In a food chain, state the trophic level at which the concentration of harmful chemicals is maximum. Why is it so ?
OR
How is ozone layer formed? State its importance to all life forms on earth? Why the amount of ozone in the atmosphere dropped sharply in the 1980 s?
Solution:
(a) If the population of carnivores decreases in ecosystem, population of herbivores will increase beyond control, they will rapidly consume large amounts of plants and fungi, growing until there is not enough food to sustain them. Autotrophs will disappear from earth due to overgrazing done by herbivores. Both the factors may disturb food chains thus affecting the ecosystem.
(b) The use of several pesticides and other chemicals to protect our crops from diseases and pests is frequently used by the humans. These chemicals are either washed down into the soil or into the water bo dies. From the soil, these are absorbed by the plants along with water and minerals, and from the water bodies these are taken up by aquatic plants and animals. This is one of the ways in which they enter the food chain. As these chemicals are not degradable, these get accumulated progressively at each trophic level. As human beings occupy the top level in any food chain, the maximum concentration of these chemicals get accumulated in our bodies. This phenomenon is known as biological magnification. This causes great risk to the health of the humans and leads to lot of diseases and disorders.
OR
Ozone at the higher levels of the atmosphere is a product of Ultraviolet Radiations(UV) radiation acting on oxygen( O 2 ) ( O 2 ) ( O )
O 2
O . + O .
O . + O 2 → O 3
Ozone
At the higher levels of the atmosphere, ozone performs an essential function. It shields the surface of the earth from ultraviolet (UV) radiation from the Sun. These radiations are highly damaging to organisms, for example, it is known to cause skin cancer in human beings.
The amount of ozone in the atmosphere began to drop sharply in the 1980 s. This decrease has been linked to synthetic chemicals like chlorofluorocarbons (CFCs) which are used as refrigerants and in fire extinguishers. Thus, the use of CFCs is the direct cause of the decrease of the ozone layer which leads to ozone depletion and in turn causes harms to humans and leads to an increase in the global earth temperature known as Global Warming.
(b) The use of several pesticides and other chemicals to protect our crops from diseases and pests is frequently used by the humans. These chemicals are either washed down into the soil or into the water bo dies. From the soil, these are absorbed by the plants along with water and minerals, and from the water bodies these are taken up by aquatic plants and animals. This is one of the ways in which they enter the food chain. As these chemicals are not degradable, these get accumulated progressively at each trophic level. As human beings occupy the top level in any food chain, the maximum concentration of these chemicals get accumulated in our bodies. This phenomenon is known as biological magnification. This causes great risk to the health of the humans and leads to lot of diseases and disorders.
OR
Ozone at the higher levels of the atmosphere is a product of Ultraviolet Radiations(UV) radiation acting on oxygen
Ozone
At the higher levels of the atmosphere, ozone performs an essential function. It shields the surface of the earth from ultraviolet (UV) radiation from the Sun. These radiations are highly damaging to organisms, for example, it is known to cause skin cancer in human beings.
The amount of ozone in the atmosphere began to drop sharply in the 1980 s. This decrease has been linked to synthetic chemicals like chlorofluorocarbons (CFCs) which are used as refrigerants and in fire extinguishers. Thus, the use of CFCs is the direct cause of the decrease of the ozone layer which leads to ozone depletion and in turn causes harms to humans and leads to an increase in the global earth temperature known as Global Warming.
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