The blank in the statement refers to a substance that is a major component of bones and proteins that build muscles. In this case, the blank is "calcium." Calcium is an essential mineral that plays a pivotal role in the development and maintenance of bones and muscles. It provides strength and structure to bones, making them hard and rigid. Additionally, calcium ions contribute to muscle contraction by binding to proteins involved in the process. Without sufficient calcium, bones can become weak and brittle, and muscle function may be impaired. To obtain this answer, one can refer to basic knowledge of human anatomy and physiology, as well as biochemistry textbooks or reliable online sources that discuss the composition and role of calcium in the human body.
