EMCC Biology Test 2 2025 Complete Practice Exam

Adenosine triphosphate (ATP) is often referred to as the energy currency of the cell. When ATP is converted to adenosine diphosphate (ADP), it releases energy that can be utilized for various cellular processes. The amount of energy released during this hydrolysis reaction, under standard conditions, is approximately 7.3 kilocalories per mole.

This energy release occurs because breaking the high-energy phosphate bond between the second and third phosphate groups (the terminal phosphate bond) allows for a more stable product (ADP and inorganic phosphate). The release of energy from ATP's conversion to ADP is crucial for driving many biological reactions, such as muscle contraction, active transport across membranes, and the biosynthesis of macromolecules.

The value of 7.3 kcal is widely accepted in biochemistry and physiology as a standard measure, illustrating how ATP hydrolysis serves as a fundamental energy source for cellular activities. Given this context, it is clear why 7.3 kcal is identified as the correct answer in this scenario, as it accurately represents the energy released from ATP during its conversion to ADP.