The double-helical structure of $DNA$ discovered by Watson and Crick is known as .....

Identify the correct matching for Euchromatin and Heterochromatin from the given statements:
$I -$ Loosely packed
$II -$ Densely packed
$III -$ Darkly stained region
$IV -$ Lightly stained region
$V -$ Transcriptionally active chromatin
$VI -$ Transcriptionally inactive chromatin
Euchromatin $\quad\quad$ Heterochromatin

Adjacent nucleotides in a polynucleotide chain are joined by

Arrange the following biological components in increasing order of their size:

How is the chromosome structured through the packaging of the $DNA$ helix? Describe in detail.

If a $DNA$ fragment contains $A = 166$ and $C = 144$,what is the total number of nitrogenous base pairs in that fragment?