Question

outside of cell
the diagram shows a pump. which labels can replace
x and the y in the diagram?
x: potassium, y: sodium
x: sodium, y: potassium
x: sodium, y: calcium
x: calcium, y: potassium
energy
inside of cell

Explanation:

The diagram shows a sodium - potassium pump. In the sodium - potassium pump, sodium ions ($\text{Na}^+$) are pumped out of the cell (against their concentration gradient) and potassium ions ($\text{K}^+$) are pumped into the cell (against their concentration gradient), and this process requires energy. Looking at the diagram, X is moving out of the cell (from inside to outside) and Y is moving into the cell (from outside to inside? Wait, no, looking at the positions: X is more outside, Y is more inside. Wait, the pump: sodium is at higher concentration outside, potassium at higher inside. So the pump moves 3 Na⁺ out (X could be Na⁺, moving from inside to outside, since inside has less Na⁺, so moving against gradient, using energy) and 2 K⁺ in (Y is K⁺, moving from outside to inside, since outside has less K⁺, moving against gradient). So X is sodium (moving out, from inside to outside, as inside has lower Na⁺), Y is potassium (moving in, from outside to inside, as outside has lower K⁺). So the correct option is X: sodium, Y: potassium.

Answer:

B. X: sodium, Y: potassium