Short duration contractions are characteristic of:

$A$: Latent period is the interval between the application of an appropriate stimulus and the initiation of contraction.
$R$: Latent period is minimum in cardiac muscle fibres.

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

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

Select the correct option for the following statements:
$(i)$ The most important respiratory organ in frogs is the skin / lungs.
(ii) Skeletal muscle / Cardiac muscle exhibits rhythmic contraction.

Match the following columns:

Column-$I$	Column-$II$
$P$. Skeletal muscle	$I$. Biceps
$Q$. Smooth muscle	$II$. Iris
$R$. Cardiac muscle	$III$. Heart