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Class 12th Biology 2015 Set1 Delhi Board Paper Solution

Question 10

Many fresh water animals can not survive in marine environment. Explain.

OR

How are productivity, gross productivity, net primary productivity and secondary productivity interrelated ?

Answer

Many freshwater fishes cannot survive in the marine environment because their bodies are not adapted to the marine environment. Freshwater fishes lose body water because of the higher concentration of salt in the surrounding water (hypertonic environment), which makes their survival difficult.



 

OR

 

Productivity: It is the rate of production of biomass at any trophic level at any given interval of time.

Gross productivity: It is the rate of production of organic matter by green plants per unit time per unit area. In other words, it is the total amount of productivity. Net primary productivity: It is the difference between gross primary productivity and the loss due to respiration.

Net primary productivity is the difference of gross primary productivity and respiratory loss