Use the following scenario to answer the question: A cell has an antiport protein on its apical surface. The cell is placed in a
solution that contains a high concentration of Na+ relative to the inside of the cell, and a high concentration of Ca⁺⁺ relative to the inside of the cell. The antiporter will move 3 Na⁺ into the cell in exchange for one Ca⁺⁺ leaving the cell. This is an example of what type of transport?
The correct answer is "Secondary active transport".
Explanation:
Secondary active transport is a form of across the membrane transport that involves a transporter protein catalyzing the movement of an ion down its electrochemical gradient to allow the movement of another molecule or ion uphill to its concentration/electrochemical gradient. In this example, the transporter protein (antiporter), move 3 Na⁺ into the cell in exchange for one Ca⁺⁺ leaving the cell. The 3 Na⁺ are the ions moved down its electrochemical gradient and the one Ca⁺⁺ is the ion moved uphill its electrochemical gradient, because Na+ and Ca⁺⁺are more concentrated in the solution than inside the cell. Therefore, this scenario is an example of secondary active transport.
