Question

which of the following is an example of an antiport transport mechanism?
multiple choice
coupling of the inward movement of water with the outward movement of a proton
simultaneous movement of an amino acid and a proton out of the cell
simultaneous movement of an amino acid and a proton into the cell
simultaneous movement of a sodium ion and a sugar into the cell
coupling of the inward movement of sodium with the outward movement of calcium

Explanation:

Antiport is a type of secondary - active transport where two substances move in opposite directions across a membrane. In the given options, the coupling of the inward movement of sodium with the outward movement of calcium involves two substances moving in opposite directions, which is characteristic of an antiport mechanism. The other options either involve substances moving in the same direction or do not match the typical ion - pairings for antiport.

Answer:

Coupling of the inward movement of sodium with the outward movement of calcium