ATP is called the energy currency of the cell because it stores energy in its phosphoanhydride bonds and can rapidly transfer a phosphate group to drive endergonic reactions.

• A. It catalyzes most metabolic reactions directly by lowering their activation energy.
• B. It is the primary long-term energy storage molecule in animals, stored in large quantities in adipose tissue.
• C. It couples energy released from catabolic reactions to cellular work by donating a phosphate group (phosphorylation) to other molecules.
• D. It is the main structural component of cell membranes and therefore provides energy through membrane fluidity.

Answer: (C)