MUSCLE PHYSIOLOGY

Detailed explanation-1: -Such mechanisms include futile cycles described as metabolic reactions that consume ATP to produce a product from a substrate but then converting the product back into the original substrate, releasing the energy as heat.

Detailed explanation-2: -Explanation: Futile cycling occurs when two metabolic processes occur in opposite directions, and thus result in no net change. This is very wasteful, and not ideal. The only example of the answer choices of metabolic processes occurring in opposite directions is glycolysis and gluconeogenesis occurring simultaneously.

Detailed explanation-3: -A metabolic futile cycle is one in which a precursor is converted into a product by a forward reaction and then resynthesized to the precursor. In such a reaction, there is no net product accumulation, but energy (ATP) is used. There are multiple examples of such futile cycles in the glucose metabolic pathway.

Detailed explanation-4: -A futile cycle, also known as a substrate cycle, occurs when two metabolic pathways run simultaneously in opposite directions and have no overall effect other than to dissipate energy in the form of heat.