SSC CGL 2025 Tier-II · Paper-I, 19 January 2026 · General Awareness · Question 6 of 150

We transcribed this text from the pictures of a candidate's response sheet for this paper; the answer is the key SSC marked with a green tick on that sheet. Solution last reviewed 11 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. This paper reaches us as a candidate's response sheet saved as pictures, so we transcribed the text from those pictures, and a second reader checked every question against them; where the layout carries meaning, we show the picture too. Each answer is the key SSC marked with a green tick on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. UnlockIAS wrote the solutions.

Which of the following biological processes explains why human muscles often feel sore or "cramped" after a sudden, intense bout of physical exercise?

(a)Accumulation of Ethyl Alcohol
(b)Excessive release of Carbon Dioxide
(c)Depletion of Vitamin C
(d)Accumulation of Lactic Acid

Answer

Why

Correct — D. In a sudden, intense burst of effort, muscle cells run short of oxygen. Glucose is still split into pyruvate in the cytoplasm, but instead of going on to carbon dioxide and water in the mitochondria, the pyruvate is turned into lactic acid.

NCERT's Class 10 text puts it directly: the build-up of lactic acid in our muscles during sudden activity causes cramps → option (d).

Why the others are wrong

(a)
Accumulation of Ethyl Alcohol — Ethyl alcohol (ethanol) is what yeast makes when it respires without oxygen, along with carbon dioxide. Human muscle takes the lactic-acid route instead.
(b)
Excessive release of Carbon Dioxide — Carbon dioxide is a product of aerobic respiration, the very pathway muscles fall short of during intense effort. Turning pyruvate into lactic acid releases no CO₂.
(c)
Depletion of Vitamin C — Vitamin C deficiency causes scurvy, a disease of long-term poor diet. It has nothing to do with one bout of exercise.

Concept

Respiration always starts the same way: glucose, a six-carbon molecule, is broken down in the cytoplasm into pyruvate, a three-carbon molecule.

What follows depends on oxygen. With oxygen, the mitochondria break pyruvate down to carbon dioxide and water and release far more energy.

Without it, yeast turns pyruvate into ethanol and carbon dioxide, and oxygen-starved muscle turns it into lactic acid.

NCERT ties lactic acid to cramps during sudden activity, and the stem borrows that word.

Soreness that peaks one to three days after exercise (delayed onset muscle soreness) is now put down mainly to tiny injuries in muscle fibres, since lactic acid clears within about an hour. The key follows the textbook pathway.

Key facts

Glucose is broken down to pyruvate, a three-carbon molecule, in the cytoplasm.
In yeast, anaerobic respiration turns pyruvate into ethanol and carbon dioxide.
In muscle cells short of oxygen, pyruvate is converted to lactic acid.
Aerobic respiration in the mitochondria breaks pyruvate down to carbon dioxide and water and releases far more energy than the anaerobic routes.

Study next

ATP as the energy currency of the cellGlycolysis, the Krebs cycle and the electron transport chainFermentation by yeast

Common traps

Choosing ethyl alcohol because it also comes from anaerobic respiration. Ethanol is the yeast route, lactic acid the muscle route.
Choosing carbon dioxide because hard exercise makes you breathe hard. The oxygen-short muscle pathway releases none.

26 Sep 2024, 12:30, GA Q.13 matches glucose, yeast, glycolysis and pyruvic acid to their roles in respiration, and 12 Sep 2025, 09:00, GA Q.13 asks which respiration pathway generates the most ATP (the electron transport chain).

Related PYQs

No directly related past PYQ was found.

Topic: Scientific Research — all 179 SSC CGL questions on it, every solved shift.