Question

What is correct about GPP and NPP in a system
A. NPP = GPP - plant respiration
B. NPP = GPP + Plant respiration
C. NPP = GPP - Animal respiration
D. NPP = GPP + Animal respiration

Answer 1

Gross primary Production (GPP) is the total rate at which material is produced and net primary production (NPP) is the rate at which material is accumulated in excess of respiration.

Complete answer:
Photosynthesis is the key process in the carbon cycle. GPP and NPP are the key variables in a carbon cycle study. Thus accurate estimation of these carbon fluxes is important for understanding the interaction between terrestrial ecosystems and atmosphere.
Gross primary production is the total rate at which material is reduced and net primary production is the rate at which material is accumulated in the excess of respiration. Another word NPP is GPP minus respiration.
Net primary production is directly related to ecosystem condition. Ecosystem where the environment most favourite plant growth and lower respiration rate will have the highest rate of NPP.
NPP is considered the total of global terrestrial NPP co-opted by human and domestic animal ranges from roughly 40-50% This indirect appropriation by a man is substantially disproportionate to direct use
(3%of global NPP.) by humans. The more human-caused NPP the less available for natural ecosystems.

Respiration is the amount of $CO_2$ that is lost from an organism on a system from metabolic activity. Respiration can be divided into components that replied to the source of the
NPP is the net amount of primary production after the cost of plant respiration is included therefore, NPP = GPP - plant respiration.
Therefore, from the above explanation the correct option is (A) NPP = GPP - plant respiration.

Note: Secondary production is the gain in Biomass of Reproduction of heterotrophs and decomposers; the rate of secondary productions is very much lower than the rates of the primary production.