Question

Read the given statements and select the correct option
Statement 1: Net primary productivity is less than gross primary productivity
Statement 2: Net primary productivity is equal to gross primary productivity minus the respiratory losses

• A. Both statements 1 & 2 are correct
• B. Statement 1 is correct but statement 2 is incorrect
• C. Statement 1 is incorrect but statement 2 is correct
• D. Both statements 1 and 2 are incorrect

Answer 1

The correct option is A Both statements 1 & 2 are correct

Primary productivity is defined as the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis. The rate of biomass production is called productivity. It is expressed in terms of g/$m^2$/yr or Kcal/$m^2$/yr
It can be divided into gross primary productivity (GPP) and net primary productivity (NPP). Gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis. However, a large amount of GPP is utilised by plants in respiration.
Therefore, gross primary productivity minus respiration losses (R), is the net primary productivity (NPP).
GPP – R = NPP
Therefore it is clear that net primary productivity is less than that of gross primary productivity.