Question

in normal adult bones, there is no turnover of minerals. osteoblast activity exceeds osteoclast activity, once bone has been formed. exercise will have no effect on bone remodeling. a portion of the protein and mineral content is replaced each year. osteoclasts continue to be active long after osteoblast activity ceases.

Explanation:

In normal adult bones, there is a continuous process of bone remodeling. Osteoblasts build bone and osteoclasts break it down. A portion of the protein - collagen and mineral - calcium salts content is replaced each year. Minerals in bones do turnover. Osteoblast and osteoclast activities are balanced in normal adult bones in a dynamic equilibrium. Exercise stimulates bone remodeling. Osteoclasts do not remain active long after osteoblast activity ceases in normal circumstances as they work in concert.

Answer:

D. a portion of the protein and mineral content is replaced each year.