Do intercostal muscles contract or relax when we breathe.

Whic disease reduces bone density and causes the bones to become brittle

Explain what causes the skin to burn in the sun? explain why people should avoid the sun if taking a photosensitive medication?

When do people generally experience rapid growth for a second time? a. between the ages of 3 and 9 b. between the ages of 9 and 12 c. between the ages of 13 and 20 d. between the ages of 25 and 29 which action occurs in the third stage of cell division? a. the nuclear material of cell is copied exactly. b. the nuclear membrane disappears. c. the cell forms two nuclei d. the nuclear material separates, with half moving to either side of the cell.