Question

In questions 18 through 22, match the description of the cellular transport process with its mechanism.

18. Na⁺ ions are actively transported from the cell to the extracellular space. Na⁺ ions ____ then flow from a concentration of 145 nM to the interior of the cell where the Na⁺ ion concentration is 12 nM. The same membrane transporter simultaneously carries glucose from a low extracellular concentration to a relatively higher concentration inside the cell.

A. Facilitated diffusion

B. Active transport

C. Secondary active transport

D. Osmosis

E. Passive diffusion

Answer 1

Secondary active transport takes place across biological membranes and is a form of active transport in which that transporter protein couples the movement of ions either down its electrochemical gradient or by their uphill movement or against the concentration gradient. Co transport mechanism. Similarly, is the case here, Na ions though actively transported from the cell interior to exterior against concentration gradient but when it flow backs from higher to lower concentration it couples glucose with itself against glucose concentration via Na/glucose transporter in the membrane.