Polytene chromosomes have a common point of attachment. What is this point called?

What is the disc-shaped structure present on the centromere of each chromosome called?

$A$ repeated cycle of $DNA$ replication without separation of daughter chromatids leads to the formation of

Nucleosome consists of

$DNA$ genetic material occurs by itself in lower organisms and combined with proteins as nucleoproteins in higher organisms. The nucleoprotein is organized in higher forms to form

Chromatin is composed of ........