One turn of the helix in a Bform $DNA$ is approximately
$2\ nm$
$20\ nm$
$0.34\ nm$
$3.4\ nm.$
The length of a helix of $DNA$ is
Chargaff's rules are applicable to
The $A/U$ and $G/U$ ratio in $RNA$ is
Genetically active area of chromosome is called
Explain the role of scientist :
$1.$ Watson and Crick $(1953)$
$2.$ Erwin chargaff