Question

in the example of secondary active transport, what would happen if atp suddenly became unavailable for step 1 (labeled 1 on a black dot on the left of the image) of the figure shown? click to view full size. extracellular fluid proton 1 adp pi atp cytoplasm protons are pumped across the membrane by primary active transport. proton concentration gradient electrical gradient 2 the proton pump generates an electrochemical gradient, with a higher concentration of protons outside the cell and a lower concentration of protons inside the cell. 3 an antiporter uses the proton electrochemical gradient to move a different molecule out of the cell against its concentration gradient. © macmillan learning all processes in this system would stop immediately. the proton gradient would remain strong and unchanged. the movement of the molecules through the antiporter would continue for a while until the proton gradient was depleted. the protons would simply diffuse through the membrane back into the cytoplasm.

Explanation:

ATP powers primary active transport to create proton - gradient for secondary active transport. Without ATP, the proton - gradient won't be replenished, but existing gradient allows antiporter to function briefly.

Answer:

The movement of the molecules through the antiporter would continue for a while until the proton gradient was depleted.