If an animal cell needs to acquire more of a particular amino acid for a physiological process, it can employ _______ when the amino acid is more concentrated inside the cell than in the extracellular fluid.
A) simple diffusion
B) facilitated diffusion
C) synthesis
D) active transport
E) osmosis

Question

Quizplus · Accepted Answer

Active transport is the process in which cells can move molecules against their concentration gradient. If a particular amino acid is needed by the cell, but its concentration is higher outside the cell than inside, the cell can use active transport to bring in more of it. This requires energy as the cell pumps the amino acid against the concentration gradient. Simple and facilitated diffusion rely on concentration gradients, so they would not be effective in this scenario. Synthesis would involve the cell making the amino acid itself, which is not always possible or efficient. Osmosis is the diffusion of water across a membrane, so it is not relevant to the uptake of amino acids.

If an Animal Cell Needs to Acquire More of a Particular