SSC CGL 2024 Tier-I · 25 September 2024, Shift 1 · General Awareness · Question 24 of 100

Text as printed on a candidate's response sheet for this shift; answer per SSC's tentative key as marked on that sheet. Solution last reviewed 10 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. The questions and options here are reproduced as printed on a candidate's own response sheet for this shift — the Commission's text, unchanged. Each answer is SSC's tentative key as marked on that sheet; SSC allowed challenges to it and never publishes a final key. The solutions are written by UnlockIAS.

Which essential amino acid enhances calcium absorption and also plays an important role in the formation of collagen?

(a)Tyrosine
(b)Histidine
(c)Lysine
(d)Arginine

Answer

Why

Correct — C. Lysine is the essential amino acid the question describes: it improves the body's absorption of calcium and is required for the formation of collagen.

Collagen gets its strength from cross-links, and those form on hydroxylysine — lysine residues hydroxylated inside the cell, a step that needs vitamin C. Without lysine there is nothing to hydroxylate.

Essential means the body cannot build it, so it has to arrive in food. That is option (c).

Why the others are wrong

(a)
Tyrosine — Tyrosine is not an essential amino acid, because the body makes it from phenylalanine. Its known roles are as a precursor of thyroid hormones, melanin and adrenaline.
(b)
Histidine — Histidine is essential, but its textbook role is as the precursor of histamine. It is not the amino acid linked to calcium absorption or to collagen.
(d)
Arginine — Arginine is only conditionally essential in adults and is known as the precursor of nitric oxide and a part of the urea cycle. Neither role is collagen or calcium.

Concept

Amino acids divide into essential ones the body cannot synthesise and must take from food, and non-essential ones it can build for itself. Nine are essential for humans.

Lysine is one of the nine, and it is the one nutrition texts tie to calcium absorption and collagen.

It is also the limiting amino acid in cereals: rice and wheat are short of lysine while pulses are rich in it. That is the biochemistry behind eating cereal and pulse together.

Arginine and histidine are often listed as conditionally essential, meaning the body's own supply falls short during growth, illness or stress. The strict nine-item list in the question's sense still counts lysine, not those two, as the answer.

Key facts

Lysine is an essential amino acid, which the body cannot synthesise and must obtain from food.
Lysine is required for the formation of collagen and improves the absorption of calcium.
Lysine is the limiting amino acid in cereals such as rice and wheat, while pulses are rich in it.
Collagen cross-linking depends on hydroxylysine, and the hydroxylation step requires vitamin C — its failure is scurvy.

Study next

The essential amino acids and the foods that supply themVitamin C, hydroxylation of proline and lysine, and the symptoms of scurvyComplementary proteins and why cereal with pulse gives a complete profile

Common traps

Picking tyrosine because it sounds biochemical, when tyrosine is non-essential and made from phenylalanine.
Reading the calcium clue as pointing to a vitamin or a mineral, when the question asks for an amino acid.

SSC keeps nutrition items to single-fact recall of a named substance. Vitamin C as ascorbic acid is asked on 23 Sep 2024, 12:30, General Awareness Q.23, and casein as the main milk protein on 19 Sep 2024, 16:00, General Awareness Q.4.

Related PYQs

No directly related past PYQ was found.