Question

according to the diagram, the movement of phosphorus between biological organisms and soil is in a steady state in an undisturbed system. which of the following best explains the reason for this steady movement?
a phosphorus is taken up by plants during photosynthesis to create carbohydrates.
b a decrease in buffer zones prevents phosphorus runoff in waterways.
c there is a rapid influx of phosphorus from the weathering of rocks.
d readily available organic phosphorus in the soil is assimilated by plants.

Explanation:

• Option A: Photosynthesis creates carbohydrates using carbon dioxide and water (not phosphorus).
• Option B: Decrease in buffer zones would likely increase phosphorus runoff, not explain steady - state movement.
• Option C: Weathering of rocks is a slow process (not rapid) in the phosphorus cycle.
• Option D: In a steady - state phosphorus cycle between soil and organisms, plants assimilate available organic phosphorus from the soil, and when organisms die, phosphorus is returned to the soil.

Answer:

D. Readily available organic phosphorus in the soil is assimilated by plants.