If a large molecule needs to move against the concentration gradient, what structure will need to be used ?

The structure of ATP will need to be used.

Explanation:

Adenosine triphosphate or ATP is an energy rich compound which undergo hydrolysis in presence of water to generate free energy.

         When a molecule is moving against its concentration gradient it requires the input of energy which is generally supplied by the hydrolysis of ATP molecules.

For example Na+K+ATPase uses the energy derived from ATP hydrolysis to transport Na+ inside the cell and K+ outside the cell.

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