Q. 224.1( 7 Votes )
What is meant by biological magnification? With the help of a food chain, explain how biological magnification of harmful chemicals can occur.
Chemicals, pesticides and heavy metals move up the food chain, get into aquatic bodies and are eaten by organisms like fishes which are in turn eaten by hawks/eagles. This process where the chemical enters the food chain and increase in concentration with increasing trophic level is known as biological magnification.
For example in the above food chain, Grass is a producer; it grows by consuming harmful chemicals from the soil. Grass is eaten by grasshopper which is further eaten by frog. Frog is eaten by snake and peacocks feed on snake. Since peacock is at the highest trophic level it will have the maximum concentration of harmful chemicals in its body, according to bio-magnification. The chemicals enter from soil to grass and they increase in concentration with increasing trophic level.
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The gas A is used by most of the animals to obtain energy from food by the process of respiration. When A is acted upon by radiation X, it gets converted into another gas B which is an allotrope of A but poisonous when inhaled. B forms a kind of layer C in the upper atmosphere which absorbs radiations X coming from a source Y and prevents them from reaching the earth. Some chemicals Z released from the various devices on the earth are destroying the layer C slowly. In fact, a hole has already been formed in layer Cover the area D of the earth.
(a) What are gases?
(i) A, and
(ii) B? Write their molecular formulae.
(b) Name the layer C.
(c) What are (i) X, (ii) Y, and (iii) Z?
(d) Name the area D.
(e) Name any two human ailments which may be caused by X.Lakhmir Singh & Manjit Kaur- Biology
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