What is the unit of crossing over?

Thirty percent of the bases in a sample of $DNA$ extracted from eukaryotic cells is adenine. What percentage of cytosine is present in this $DNA$ (in $\%$)?

If a $DNA$ molecule contains $10,000$ base pairs, how many nucleotides does it have?

Which molecule is inherited by the offspring produced by parents?

Which type of $RNA$ is found in the highest quantity in a cell?

Histones are rich in the basic amino acid ............... and ...............