Which of the following is not a contractile protein?

The largest muscle in the human body is . . . . . . .

Actin and myosin proteins are related with

The muscular contraction in which the tension remains the same and the mechanical work is also done is called

Which ion is essential for muscle contraction?

Select the correct option for skeletal muscle.
$(I)$ In human body,it is made of a number of muscle bundles.
$(II)$ Muscle bundles contain a number of muscle fibers and each fiber is lined by the sarcolemma.
$(III)$ In a muscle fiber,the sarcoplasm contains only one nucleus.
$(IV)$ In a muscle fiber,the sarcoplasmic reticulum is the storehouse of calcium ions.