Who put forward the sliding filament theory?

Which protein is distributed at regular intervals on the tropomyosin protein?

$A : Ca^{2+}$ plays an important role in muscle contraction.
$R : Ca^{2+}$ combines with the troponin chain,displacing tropomyosin and allowing the myosin head to combine with actin to form an actomyosin complex.

Which of the following does not consist solely of involuntary muscles?

Which of the following is the contractile protein of a muscle?

Label the different components of the actin filament in the diagram given below.