Question

(a) what is reflex arc
(b)how do muscles cell move

Answer 1

reflex arc is the nerve path through which an reflex action is travel.
The muscle cells have special proteins, which in response to nervous electrical impulses change their shape and their arrangement in the muscle cell. .

Answer 2

(i)The pathway taken by nerve impluses in a reflex action is called the reflex arc. They allow rapid response, e.g. pulling of hand on touching a hot object.
(ii) Muscle cells have special proteins that change their shape and arrangement in the cell in response to electrical impulse. This forces the muscle cells to contract and relax, causing their movement.