$A$ $DNA$ polymer has a free phosphate group at one end of the sugar,which is called the $P$ end of the polynucleotide chain. Similarly,at the other end of the polymer,there is a free $OH$ group of the sugar,which is called the $Q$ end of the polynucleotide chain.
$\quad P \quad Q$

If an isolated strain of $DNA$ is kept at $82-90^{\circ}C$,then

Identify the correct sequence of genetic material in descending order of size (from largest to smallest).

Read the following statements and choose the set of correct statements:
$(a)$ Euchromatin is loosely packed chromatin
$(b)$ Heterochromatin is transcriptionally active
$(c)$ Histone octamer is wrapped by negatively charged $DNA$ in nucleosome
$(d)$ Histones are rich in lysine and arginine
$(e)$ $A$ typical nucleosome contains $400 \ bp$ of $DNA$ helix
Choose the correct answer from the options given below:

Which molecule is removed when an adenine nitrogenous base attaches to the first carbon of a ribose pentose sugar?

Which of the following nitrogenous bases is not found in $DNA$?