$A$ chromosome in which the centromere is situated close to its end so that one arm is very short and the other very long is:

$S$ - Statement: $RNA$ and protein molecules move between the nucleoplasm and the cytoplasm.
$R$ - Reason: Nuclear pores are present at several locations in the nuclear envelope of the nucleus.

When the centromere is situated in the middle of the two equal arms of a chromosome,it is called:

Chromatin contains:

What is a centromere? How does the position of the centromere form the basis of the classification of chromosomes? Support your answer with a diagram showing the position of the centromere on different types of chromosomes.

$A$ : The nucleus of a plasma cell has a cart-wheel appearance.
$R$ : The nucleus contains peripheral clumps of heterochromatin.