Identify the incorrect statement from the following.
A. The reservoir pool for the phosphorus cycle is the earth’s crust whereas the atmosphere is the reservoir pool for the carbon cycle.
B. During the carbon cycle and phosphorus cycle, there is very high respiratory release of carbon and phosphorus respectively.
C. Atmospheric inputs of phosphorus through rainfall are much smaller than carbon inputs.
D. Gaseous exchange of phosphorus between organisms and the environment are negligible.

Hint: The phosphorus is a very crucial element for the growth and development of the plants and also it helps in building the cell membrane. The requirement of phosphorus is fulfilled through the soil and water having phosphorus but the carbon is made available to plants only via gaseous exchange.

Complete answer: We all know phosphorus and the carbon cycle are the two different cycles which happen together in the atmosphere completely independent of each other. Both the cycles are termed as Biogeochemical cycles as they require both the activity of living as well as non-living components. The reservoir for the phosphorus cycle is mainly the earth’s crust as these rocks break down due to erosion or weathering. As a result the water will take the phosphorus along with it into the water body and as water will flow over land some of the phosphorus will get deposited into the soil also. We know that plants can take up phosphorus from the soil but they also have the ability to take up phosphorus from the water directly. Then when plants die the phosphorus gets deposited and accumulated in the soil itself and the cycle begins again. There are no respiratory pathways for the flow of the phosphorus into the atmosphere.
Now if we talk about the carbon cycle, the main reservoir for carbon is the atmosphere because the human being breathes out carbon which is taken up by the plants and the cycle thus continues. The phosphorus is never accumulated into the atmosphere in gaseous form so the chances of having gaseous exchange between organisms is almost zero.
So, the correct answer is “Option B”.

Note: In addition to the availability of carbon through the atmosphere, the carbon cycle also receives its carbon from the burning of any organic material, through emissions of the factories and also when any living organism dies the carbon from it gets deposited in the soil which is taken up by the roots for photosynthesis and thus the cycle of carbon continues.