Which replacement of amino acid does not alter its normal function?

Ans. (D) Glutamine replaced by asparagine(Ref: Lehninger Principle of Biochemistry 6th Ed; Page No- 3-5)The concept is discussed in this question is the conservative or homologous replacement of amino acids.If replaced Amino acid belong to same category like hydrophobic or hydrophilic: no alteration in function.So Glutamine to asparagine is correct answer; because Asparagine and glutamine both are uncharged polar (hydrophilic) amino acids. Thus, when replacement with asparagine there no change in the polarity o the charge of the peptide/Protein.