Chromatin contains:

$A$ chromosome in which the $centromere$ is situated near one end is known as

Which of the following is associated with the synthesis of ribosomal $RNA$ $(rRNA)$?

The pars granulosa of the nucleolus is primarily composed of:

Select the correct option for the following matches:

Column-$I$	Column-$II$
$(1)$ Chromosome arms are of equal length	$(a)$ Submetacentric
$(2)$ One arm of the chromosome is shorter	$(b)$ Acrocentric
$(3)$ One arm is extremely long and the other is very short	$(c)$ Telocentric
$(4)$ Terminal centromere	$(d)$ Metacentric

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.