Which of the following is not an essential amino acid?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Alanine
Amino acids are classified by whether the body can make them:
Non-essential amino acids can be synthesised in the body: glycine, alanine, serine, cysteine, tyrosine, proline, aspartic acid, glutamic acid, asparagine, glutamine.
Essential amino acids cannot be synthesised and must come from the diet: valine, leucine, isoleucine, lysine, arginine, histidine, threonine, methionine, phenylalanine, tryptophan.
Histidine, phenylalanine and lysine are essential amino acids, so the one that is not an essential amino acid is alanine.
NCERT (2026-27 edition):
Classification of Amino Acids – “… The amino acids, which can be synthesised in the body, are known as non-essential amino acids. On the other hand, those which cannot be synthesised in the body and must be obtained through diet, are known as essential amino acids (marked with asterisk in Table 10.2).”
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| 07-06 S2 | 14-05 S2 | – | – | – |