Of the amino acids found in proteins, how many can be synthesised by the human body?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 10
Amino acids that the body can make are non-essential amino acids; those it cannot make are essential amino acids and must come from the diet.
Amino acids found in proteins: about 20 (all listed in Table 10.2).
Essential amino acids: the 10 marked with an asterisk, which the body cannot synthesise.
Non-essential amino acids: 20 − 10 = 10, which the body can synthesise.
NCERT (2026-27 edition):
10.2.2 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).”
Summary – “… Proteins are the polymers of about twenty different α-amino acids which are linked by peptide bonds. Ten amino acids are called essential amino acids because they cannot be synthesised by our body, hence must be provided through diet.”
Table 10.2: Natural Amino Acids
