Final answer:
Small amounts of waste products from cell metabolism are lost through the skin by perspiration. This process is part of the body's excretory function to maintain homeostasis, with sweat glands in the skin expelling excess water, salts, and urea.
Step-by-step explanation:
The small amounts of waste products from cell metabolism are lost through the skin by C) Perspiration.
Excretion is the bodily process of discharging wastes. The human body eliminates waste products and excess water through several organs as part of maintaining homeostasis. One of the key functions of the skin is to excrete waste through the production of sweat, which includes water, salts, and small amounts of urea.
Urea is a byproduct of protein catabolism, and it is removed from the body alongside excess salts and water when we sweat. Meanwhile, other organs also participate in excretion such as the kidneys filtering blood to create urine, the liver breaking down substances and excreting bile, the lungs releasing carbon dioxide and water vapor during exhalation, and the large intestine eliminating solid waste.