Continuity of life from generation to generation in organisms is maintained by which of the following?

Which nitrogenous base is $NOT$ present in the structure of $DNA$?

The percentage of $(G + C)$ in a $DNA$ molecule is given by:

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

Identify the pair of nucleotides in $DNA$ that are linked by three hydrogen bonds.

The smallest structure having the power of replicating itself is: