Genetic mutations occur in which of the following?

Who first suggested the idea of circular flow of genetic information?

The one-gene-one-enzyme relationship was first established in.....

Match the following columns:

Column-$I$	Column-$II$
$(p)$ $AUG$	$(a)$ Transposons
$(q)$ $UGA$	$(b)$ Jacob and Monod
$(r)$ Jumping genes	$(c)$ Termination codon
$(s)$ Operon model	$(d)$ Methionine

Read the following four statements ($1$ to $4$):
$1$. In transcription,uracil pairs with adenosine.
$2$. Regulation of $lac$ operon by a repressor is referred to as positive regulation.
$3$. The human genome contains approximately $50,000$ genes.
$4$. Haemophilia is a sex-linked recessive disease.
How many of the above statements are correct?

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