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ATP is used to actively transport H+ out of the cell against the concentration gradient. The H+ & sucrose cotransporter, for example, then uses this proton gradient for transport. H+ goes back into the cell with the gradient (passively) with concomitant sucrose transport across the membrane. Is this active or passive transport?

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Co-transport, also called secondary active transport, is a form of active transport because it is using the energy from one concentration gradient to transport another molecule across the membrane against its concentration gradient. The concentration gradient which drives this process requires energy to set up in the first place, which is why co-transport is considered active.

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