Final answer:
Increased metabolism results in heightened cellular respiration, producing more ATP. Excess energy the body can't immediately use is stored as fat, following option a) Decreases energy production, stores excess energy as fat.
Step-by-step explanation:
Increased metabolism refers to the body's enhanced capability to convert food into energy, which leads to an increase in cellular activities including cellular respiration. Cellular respiration is the process by which cells produce ATP (adenosine triphosphate), the primary molecule for storing and transferring energy in cells. The relationship between increased metabolism and cellular respiration is that when metabolism is increased, cells consume more oxygen and glucose to produce more ATP through cellular respiration.
When the body has excess energy that it cannot use immediately, it does not decrease energy production. Instead, it stores this excess energy as fat (the body do with energy it can't use); this storage is a biological mechanism to ensure energy availability during times when food is scarce or when there are increased energy demands.
The correct answer to what the body does with energy it can't use is: a) Decreases energy production, stores excess energy as fat. This leads to the accumulation of adipose tissue, which is the body's way of storing surplus energy for future use.