Which of the following means of transport would most likely be used for moving a medium- sized molecule like a monosaccharide or an amino acid) from a low concentration on the outside of a cell to a high concentration on the inside of a cell?
A) active transport through a "pump" protein
B) facilitated diffusion through an ion channel protein
C) facilitated diffusion through a transporter protein
D) passive transport

Question

Quizplus · Accepted Answer

Moving a molecule against its concentration gradient (from low to high concentration) requires energy input, which is provided by active transport through a "pump" protein. Facilitated diffusion through a transporter protein or ion channel protein only moves molecules down their concentration gradients (from high to low concentration), while passive transport also does not require energy input and also moves molecules down their concentration gradients.

Which of the Following Means of Transport Would Most Likely