Class 12th Biology 2014 Set2 Delhi Board Paper Solution
Question 23
(i) What is primary productivity ? Why does it vary in different types of ecosystems?
(ii) State the relation between gross and net primary productivity.
Answer
(i) The amount of biomass produced per unit area in a certain time period by plants through photosynthesis is defined as primary productivity. It depends upon the type of plant species associated with an ecosystem, photosynthetic capacity of these plants and nutrient availability. This is the reason why it varies in different types of ecosystems.
(ii) The relation between the gross and net primary productivity can be shown as:
Pn = Pg - R
where,
Pn = Net primary productivity
Pg = Gross primary productivity
R = Respiration
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