The structural formula of the pentose sugar present in $DNA$ is given. Select the correct group for the position marked '$X$' from the options.

Which of the following organisms has been used for genetic research?

$DNA$ generally acts as a template for the synthesis of:

$A$ mutant micro-organism unable to synthesize a compound required for its growth but able to grow if the compound is provided,is known as

Read the following statements and select the correct statements:
$(A)$ Essential life processes such as metabolism,translation and splicing are evolved around $\text{RNA.}$
$(B)$ Heavy isotope of nitrogen $(^{15}N)$ is a radioactive isotope,while light isotope of nitrogen $(^{14}N)$ is not a radioactive isotope.
$(C)$ The codon in $\text{rRNA}$ is read in a contiguous fashion.
$(D)$ In the first phase of translation,amino acids are activated in the presence of $\text{ATP.}$
$(E)$ $\text{DNA}$ from every tissue from an individual shows a high degree of polymorphism.
Choose the correct answer from the options given below:

Statement $P$: $m-RNA$ contains $75$ nucleotides.
Statement $Q$: There are $20$ types of $t-RNA$ in the cytoplasm.