In one turn of the $DNA$ helix,there are $.........\,bp$ and its length is $.........$.

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 correct features of $DNA$ from the following statements:
$(i)$ It is made of two polynucleotide chains.
(ii) The backbone is constituted by sugar and phosphate.
(iii) The two chains have anti-parallel polarity.
(iv) The bases in the two strands are linked through $H$-bonds.
$(v)$ Both chains are coiled in a right-handed fashion.

Genetic information is carried by long-chain molecules made up of

Which nitrogenous base is $NOT$ present in $DNA$?

In the structure of $DNA$,which components are positioned opposite to each other,at an equal distance,and in opposite directions?