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

The carrier of heredity is:

Which of the following is correct for Watson and Crick's model of $DNA$? It is a duplex with

What is the reason for the anti-parallel nature of $DNA$ strands?

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 of the following radiations causes damage to $DNA$?