Some chromosomes have non-staining secondary constrictions at a constant location. This gives the appearance of a small fragment called the ......

What is the approximate size of the nucleus in a typical mammalian cell?

What is meant by a satellite in the context of chromosomes?

Identify the cell organelle based on the following characteristics:
- It is not a membrane-bound organelle.
- It is the site for active ribosomal $RNA$ $(rRNA)$ synthesis.
- It is a spherical structure.

During anaphase,chromosomes appear in various shapes due to the presence of:

In the given figure,what is the structure labeled as $A$?