Question

Intestinal epithelial cells pump glucose into the cell against its concentration gradient using the Na-glucose symporter. What is the mechanism by which glucose is transported into the cell?

1) Facilitated diffusion
2) Active transport
3) Simple diffusion
4) Osmosis

Answer 1

Glucose is transported into intestinal epithelial cells against its concentration gradient using active transport, specifically through a Na-glucose symporter, which is an example of secondary active transport that requires energy.

Step-by-step explanation:

The mechanism by which glucose is transported into intestinal epithelial cells against its concentration gradient is through active transport. Specifically, this occurs using a Na-glucose symporter, which is an example of secondary active transport. The symporter uses the energy from the movement of Na+ ions down their electrochemical gradient, which is maintained by the Na+/K+ ATPase pump. The Na+/K+ ATPase pump actively expels Na+ ions out of the cell in exchange for K+ ions and uses ATP in the process. Because glucose enters the cell against its concentration gradient utilizing the energy derived from this ionic movement, it is indeed active transport.

Thus, the correct answer to the student's question is (2) Active transport. Intestinal epithelial cells use active transport to move glucose into cells against its concentration gradient, which is essential for efficient absorption of nutrients.