How many genetic codes specify the amino acid proline?

The initiation codon is ...... .

The 'one gene, one enzyme' hypothesis was proposed by . . . . . . .

Out of $64$ codons,$61$ codons code for $20$ types of amino acids. This phenomenon is called:

Which of the following amino acids is coded by a single codon?

Dr. Khorana prepared an artificial mRNA containing $CUCUCUCUCU$ nucleotides; its translation resulted in the formation of a polypeptide chain bearing alternately arranged . . . . . . and . . . . . . amino acids,respectively.