Question

in the examples shown, the movement of ____________ down its concentration gradient provided the energy to move the other substances against their respective concentration gradients. h+ k+ na+ glucose

Explanation:

In cellular transport, the movement of $H^+$ down its concentration gradient is often used in chemiosmosis and secondary - active transport to provide energy for moving other substances against their concentration gradients. This is a common mechanism in biological systems such as in the electron - transport chain and in some transporters.

Answer:

A. $H^+$