What source of fuel is used by the body during long periods of low-intensity exercise, such as a day-long hike?

The fatty acids stored in the adipose tissues.

Explanation:

The adipose tissues are connective tissues that consist fat cells known as the adipocytes.

They are found all around the body. Those that are found under the skin are subcutaneous fat, while those that are found in the abdominal cavity, around the internal organs are visceral fats.

The adipose tissues store energy in form of fat, and insulate the body.

a. the production of carbon dioxide through the process of photosynthesis

answer: accepted answer: aquatic animals use the oxygen dissolved in water to carry out respiration. since the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air, therefore the rate of breathing in aquatic animals is much faster than it is in terrestrial animals.

explanation: