$A$ ...... muscle rotates the forearm to turn the palm downwards.

Which one of the following pairs of chemical substances is correctly categorized?

During muscular contraction,which of the following events occur?
$(a)$ $'H'$ zone disappears
$(b)$ $'A'$ band widens
$(c)$ $'I'$ band reduces in width
$(d)$ Myosin hydrolyzes $ATP$,releasing the $ADP$ and $\Pi$
$(e)$ $Z$-lines attached to actins are pulled inwards
Choose the correct answer from the options given below.

Which part of a muscle cell is the storehouse of calcium ions?

Between two successive $M$-lines,there is/are:

What are $P, Q,$ and $R$ in the given diagram?
$P \quad\quad Q \quad \quad R$