Answer the question on basis of the passage given below:
In zwitter ionic form, amino acids show amphoteric behaviour as they react both with acids and bases.
Except glycine, all other naturally occurring \(\alpha \)- amino acids are optically active, since the \(\alpha \)-carbon atom is asymmetric. These exist both in 'D' and 'L' forms. Most naturally occurring amino acids have L-configuration. L-amino acids are represented by writing the \(NH_2\) group on the left hand side.
Which of the following amino acid is essential?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Valine
Essential amino acids cannot be made in the body and must come from the diet:
Non-essential amino acids (made in the body): glycine, alanine, serine, cysteine, tyrosine, proline, aspartic acid and glutamic acid.
Essential amino acids: valine, leucine, isoleucine, arginine, lysine, threonine, methionine, phenylalanine, tryptophan and histidine.
So the essential amino acid among the options is valine.
NCERT (2026-27 edition):
Classification of Amino Acids
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| 15-05 S1 | – | 29-05 S1 | 13-06 S3 | 17-08 S1 |