Final answer:
ATP performs work by direct transfer of a phosphate group during phosphorylation, releasing energy used in various cellular processes.
Therefore, Option A is correct.
Step-by-step explanation:
ATP performs work by direct transfer of a phosphate group to another molecule. This is a process known as phosphorylation, which occurs during the hydrolysis of ATP. When the terminal phosphate group is removed from ATP, energy is released and used for various cellular processes such as muscle contraction, active transport like the sodium-potassium pump, and other metabolic reactions that require energy.
Phosphorylation is significant because the molecule that receives the phosphate group is at a higher-energy state, making it less stable and more reactive. This added energy allows the molecule to undergo chemical reactions that are typically endergonic, meaning they require an input of energy to proceed. The coupling of the exergonic reaction of ATP hydrolysis with these endergonic reactions allows cells to perform necessary work efficiently.