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

The sugar found in polynucleotides is either $A$ or $B$. Choose the appropriate options to fill the blanks $A$ and $B$.

If Adenine makes $30\%$ of the $DNA$ molecule,what will be the percentage of Thymine,Guanine,and Cytosine in it?

What is the length of one full turn of the $DNA$ helix?

If the sequence of one strand of $DNA$ is $5^{\prime}-ATGCATCG-3^{\prime}$,find the sequence of the complementary strand in the $5^{\prime} \rightarrow 3^{\prime}$ direction.

The variation in $DNA$ among different organisms is due to the sequence of: