Give scientific reasons: The genetic code is a triplet.

(N/A) There are $20$ types of amino acids found in living organisms. If the genetic code were a singlet (using $1$ nitrogenous base),it would only code for $4$ amino acids. If it were a doublet (using $2$ nitrogenous bases),it would code for $4^2 = 16$ amino acids,which is insufficient to cover all $20$ amino acids. Therefore,as proposed by George Gamow,the genetic code must be a triplet ($4^3 = 64$ combinations),which provides $64$ codons,more than enough to specify the $20$ amino acids.