Assume that the transport of a particular amino acid across the plasmalemma is observed 1) to occur only down its concentration gradient and 2) to slow when a similar amino acid is added to the extracellular fluid. The movement of the amino acid through the membrane is most likely by
A) osmosis.
B) active transport.
C) facilitated diffusion.
D) diffusion.
E) pinocytosis.

Question

Quizplus · Accepted Answer

The transport of the amino acid is facilitated diffusion because it occurs down its concentration gradient and is affected by the presence of a similar amino acid, indicating competition for a carrier protein.

Assume That the Transport of a Particular Amino Acid Across