Which of the following muscles act involuntarily?
$(a)$ Striated muscles $(b)$ Smooth muscles
$(c)$ Cardiac muscles $(d)$ Skeletal muscles

Latissimus dorsi muscles are:

Which of the following statements about the molecular arrangement of actin and myosin are correct?
$I.$ Each actin (thin filament) is made up of $2$ $F$ (filamentous) actins.
$II.$ $F$-actin is the polymer of $G$ (globular) actin.
$III.$ $2$ $F$-actins are twisted into a helix.
$IV.$ Two strands of tropomyosin (protein) lie in the grooves of $F$-actin.
The correct option is:

Visceral muscles are involved in which functions?

The actin filament is shown below. Where does $Ca^{++}$ bind during muscle contraction?

What is the full form of the following terms used in muscle structure?
$(1)$ $A$-disc
$(2)$ $I$-disc