Question

When does the cell have to use active transport?

A. when the cell is low on energy
B. when the cell is in a highly concentrated solution
C. to move molecules across the membrane quickly
D. to move molecules across the membrane against a gradient

Answer 1

the answer is to move molecules across the membrane against a gradient.

Answer 2

The correct answer is option D. "to move molecules across the membrane against a gradient".

Step-by-step explanation:

Active transport in cellular biology takes place when a cell has to move molecules or ions across the membrane from a region of lower concentration to a region of higher concentration. The cells needs to consume energy for this type of transport, which contrast with passive transport, at which the transport is in favor of the gradient and no energy input is needed.