Answer:
A. The energy released from ATP based on the model is from the hydrolysis of the terminal phosphate group in ATP.
B. ATP in cells serves as a source of energy for cellular work/activity.
Explanation:
A. The energy released from ATP based on the model is from the hydrolysis of the terminal phosphate group in ATP. This hydrolysis of the terminal phosphate group of ATP proceeds with the release of a large amount of energy. This energy is called standard free energy of hydrolysis of ATP and is relatively large under standard conditions; about -30.5 kJ/mol.
The removal of the terminal phosphate group is able to release this amount of energy because it relieves some of the electrostatic repulsion of the negative charges the three phosphate groups in ATP. Also resonance stabilization of the released phosphate group contributes to the energy released.
B. ATP in cells serves as a source of energy for cellular work/activity. The hydrolysis of the high-energy phosphate bonds as well as the coupling of the energy released to energy-requiring reactions in the cell is the mechanism used by the cells to utilize the energy released by ATP. This couplingis usually in the form of transfer of a phosphoryl group, pyrophosphoryl group, or adenylyl group from ATP to a substrate or enzyme which then uses the energy released to transform substrates to products.
