Which of the following is NOT a function of proteins in the body?
- A. Acting as enzymes
- B. Transporting oxygen
- C. Providing antibodies for defence
- D. Serving as the main long term energy store
Explanation
The body stores energy as fat and, in the short term, as glycogen, and proteins are broken down for energy only when those stores are exhausted, since doing so sacrifices functional tissue. Enzymes, haemoglobin and antibodies are all proteins, as are hormones such as insulin and structural materials such as collagen. This breadth of function is why protein is an essential part of the diet.