Question

Sodium-linked glucose transport, where both Na⁺ and glucose are moving in the same direction, is an example of

a) Cotransport.
b) Countertransport.
c) Facilitated diffusion.
d) Active transport.

Answer 1

The sodium-linked glucose transport is an example of cotransport, specifically a symport mechanism that is part of secondary active transport. This process uses the energy from the sodium ion gradient to facilitate the movement of glucose against its concentration gradient into the cell.

Step-by-step explanation:

Sodium-linked glucose transport, where both Na⁺ and glucose are moving in the same direction, is an example of cotransport. This is due to symport mechanisms which move two or more substances in the same direction simultaneously across the cell membrane.

This particular type of cotransport is also known as secondary active transport, because it relies on the electrochemical gradient established by ATP-powered pumps, such as the Na⁺/K⁺ ATPase. In the example given, the Na⁺/glucose symporter uses the energy from the sodium ion gradient to move glucose into the cell against its concentration gradient. This is facilitated by the cotransporter protein, which moves glucose into the cell as Na⁺ moves down its gradient created by the Na⁺/K⁺ ATPases on the basal membrane.