Help! this is due today!!
 1) Why do muscle cells have so many mitochondria?
 A: The mitochondria in muscle cells are smaller so more are needed.
 B: Muscle cells are bigger than every other cell and can fit more mitochondria.
 C: There are more mitochondria only because there are more nuclei.
 D: Muscle cells need to quickly respond to energy needs.
 2) What is the effect when a muscle contracts? *
 A: The muscle pushes on another muscle.
 B: The muscle pushes on a bone.
 C: The muscle lengthens.
 D: The muscle shortens.
 4) Which of the following is stored in the skeletal system?
 A: potassium
 B: calcium
 C: sodium
 D: water