Which of these statements describes carrier-mediated transport
A)It involves a specific membrane protein that serves as a carrier molecule.
B)It always transports substances against a concentration gradient.
C)It always requires energy expenditure.
D)It always transports substances along a concentration gradient.

Question

Quizplus · Accepted Answer

Carrier-mediated transport relies on specific membrane proteins that serve as carriers for molecules or ions. These carriers facilitate the movement of substrates across the membrane by binding to them on one side of the membrane and then releasing them on the other side. This process can happen either along or against a concentration gradient, and it may or may not require energy expenditure. Therefore, answers B, C, and D are incorrect because they incorrectly assume that carrier-mediated transport always occurs in a particular direction or with a specific energy requirement.

Which of These Statements Describes Carrier-Mediated Transport