Match List-I (Amino acid) with List-II (Example)
|
List-I Amino acid |
List-II Example |
|
(A) Basic amino acid |
(I) Glycine |
|
(B) Acidic amino acid |
(II) Alanine |
|
(C) Neutral amino acid |
(III) Proline |
|
(D) Optically inactive amino acid |
(IV) Lysine |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A)-(IV), (B)-(III), (C)-(II), (D)-(I)
α-Amino acids, \( \ce{H2N-CH(R)-COOH} \), are classed by the number of amino and carboxyl groups. One –\( \ce{NH2} \) and one –COOH make the amino acid neutral; an extra –\( \ce{NH2} \) in the side chain makes it basic; an extra –COOH makes it acidic. Every α-amino acid except glycine has four different groups on the α-carbon and is optically active.
(A) Basic amino acid — This matches (IV) Lysine. Its side chain \( \ce{-(CH2)4NH2} \) carries a second amino group.
(B) Acidic amino acid — This matches (III) Proline. It is the List-II item left once lysine, alanine and glycine are placed.
(C) Neutral amino acid — This matches (II) Alanine. Its side chain is \( \ce{-CH3} \), so it has one amino and one carboxyl group.
(D) Optically inactive amino acid — This matches (I) Glycine. Its side chain is H, so the α-carbon carries two hydrogen atoms and is not chiral.
Shortcut: (A)-(IV) appears only in Option (1).
Note: It seems that there is a mistake in the original NTA paper. Proline is a neutral amino acid, not an acidic one; the acidic amino acids, such as aspartic acid and glutamic acid, have a second –COOH group.