Short Answer TypeApart from being a part of the food chain, predators play other important roles. Mention any two such roles supported by examples.
How are productivity, gross productivity, net primary productivity and secondary productivity interrelated?
Long Answer TypeShort Answer TypeLong Answer TypeExplain how does:
(a) a primary succession start on a bare rock and reach a climax community?
(b) the algal bloom eventually choke the water body in an industrial area?(a) Explain primary productivity and the factors that influence it.
(b) Describe how do oxygen and chemical composition of detritus control decomposition?
Short Answer TypeWith the help of a flow chart, show the phenomenon of biomagnification of DDT in an aquatic food chain.
Biomagnification is the increase in the concentration of a toxin at successive trophic levels. The toxin gets accumulated because a toxic substance cannot be metabolised or excreted, and is thus passed on to the next higher trophic level. For example, DDT (dichlorodiphenyltrichloroethane) and other heavy metals such as mercury and cadmium are the toxins that cause biomagnification. In the aquatic ecosystem the concentration of DDT increases at successive trophic levels; it is present in low amount in water and reaches a high concentration in fish-eating birds through biomagnification. Very high concentrations of DDT
disturb calcium metabolism in birds, which causes thinning of eggshell and their premature breaking,eventually causing the decline in bird populations.
Flowchart of biomagnification of DDT
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