Questions: The source of energy for bonding between myosin and actin is Multiple Choice ATP. ADP. creatine phosphate. lactic acid.

The answer is the first one (A): ATP.

Explanation for each option:

• ATP: Adenosine triphosphate (ATP) is the primary source of energy for muscle contraction. It provides the necessary energy for the myosin heads to bind to actin filaments, allowing the muscle contraction cycle to proceed.

• ADP: Adenosine diphosphate (ADP) is a product of ATP hydrolysis. While it is involved in the energy cycle, it does not provide the energy for the initial bonding between myosin and actin.

• Creatine phosphate: This molecule serves as a quick energy reserve in muscle cells, helping to regenerate ATP from ADP. However, it is not the direct source of energy for the myosin-actin interaction.

• Lactic acid: Lactic acid is a byproduct of anaerobic metabolism in muscles. It does not provide energy for muscle contraction but can accumulate during intense exercise.

In summary, ATP is the direct source of energy for the bonding between myosin and actin during muscle contraction.