Carrier-mediated transport is necessary when
A) diffusion will not allow adequate amounts of a substance to enter the cell.
B) movement into the cell is against a concentration gradient.
C) the level of nutrients in nature is very low.
D) nutrient concentration is very low in the environment, is higher inside of the cell, or diffusion is not possible.

Question

Quizplus · Accepted Answer

Carrier-mediated transport is necessary when nutrient concentration is very low in the environment, is higher inside of the cell, or diffusion is not possible. This is because carrier proteins bind to specific substances and transport them across the cell membrane, even against a concentration gradient. Diffusion may not be sufficient in these cases, and carrier-mediated transport is required to ensure adequate uptake of nutrients.

Carrier-Mediated Transport Is Necessary When