SSC CGL 2025 Tier-I · 17 September 2025, Shift 1 · General Awareness · Question 14 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 13 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. From 2025 the candidate response sheet prints every question and option as a picture, so the text here is transcribed from those pictures for this shift and checked against them independently; where the layout carries meaning, the picture is shown as well. Each answer is the key SSC colour-marked 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. The solutions are written by UnlockIAS.

Read the following statements about aerobic respiration: 1. Glycolysis occurs in the mitochondria. 2. Kreb’s cycle occurs in the mitochondrial matrix. 3. The final electron acceptor in aerobic respiration is oxygen. Which of the above statements are correct?

(a)Only 1 and 2 are correct
(b)Only 2 and 3 are correct
(c)Only 1 and 3 are correct
(d)1, 2 and 3 all are correct

Answer

Why

Correct — B. Statement 1 is false. Glycolysis splits glucose into pyruvate in the cytoplasm, before anything enters the mitochondrion.

Statement 2 is true. The Krebs cycle runs in the mitochondrial matrix.

Statement 3 is true. At the end of the electron transport chain, oxygen accepts the electrons and forms water. That leaves 2 and 3: option (b).

Why the others are wrong

(a)
Only 1 and 2 are correct — Keeps the false statement 1. Glycolysis runs in the cytoplasm, not the mitochondria, and this option also drops the true statement that oxygen is the final electron acceptor.
(c)
Only 1 and 3 are correct — Keeps statement 1 and drops statement 2. Glycolysis is cytoplasmic, and the Krebs cycle is the stage that really does run in the mitochondrial matrix.
(d)
1, 2 and 3 all are correct — Statement 1 breaks 'all three'. Glucose is split in the cytoplasm, and it is pyruvate, the product of that split, that enters the mitochondrion.

Concept

Aerobic respiration releases energy from glucose in three stages, and each has its own place in the cell.

Glycolysis splits glucose into two molecules of pyruvate in the cytoplasm. Pyruvate then enters the mitochondrion, where the Krebs cycle runs in the matrix.

The electron transport chain on the inner mitochondrial membrane passes electrons to oxygen, which forms water. Most of the ATP is made at this last stage.

NCERT Class 10 (Life Processes) draws the same split: glucose becomes pyruvate in the cytoplasm, and pyruvate is broken down using oxygen in the mitochondria.

Key facts

Glycolysis, the splitting of glucose into pyruvate, takes place in the cytoplasm.
The Krebs cycle takes place in the mitochondrial matrix.
Oxygen is the final electron acceptor of the electron transport chain and is reduced to water.
The electron transport chain, on the inner mitochondrial membrane, yields most of the ATP of aerobic respiration.

Study next

Anaerobic respiration: lactic acid in muscle, ethanol in yeastATP yield of glycolysis, the Krebs cycle and the electron transport chainStructure of the mitochondrion: outer membrane, cristae and matrix

Common traps

Placing all of respiration inside the mitochondrion because it is the 'powerhouse': glycolysis happens before pyruvate ever gets there.
Naming carbon dioxide or NAD as the final electron acceptor: oxygen takes the electrons at the end of the chain.

Here three statements each pin a stage to its place in the cell. The stage that yields the most ATP is asked on its own at 12 Sep 2025, 09:00, GA Q.13 (keyed: electron transport chain).

Related PYQs

No directly related past PYQ was found.

Topic: Scientific Research — all 220 SSC CGL questions on it, every solved shift.