The end product of glycolysis is

Analyze the question: It asks for the end product of glycolysis, the first stage of respiration.

Explain the concept: Glycolysis takes place in the cytoplasm of the cell and does not need oxygen. It breaks one molecule of glucose (6 carbons) into two molecules of pyruvic acid (pyruvate, 3 carbons each).

Step-by-step solution:

1. Glucose (6C) is phosphorylated using 2 ATP.
2. The 6-carbon sugar is split into two 3-carbon molecules.
3. These are oxidised, producing 2 NADH and 4 ATP (a net gain of 2 ATP).
4. The final product is 2 molecules of pyruvic acid.

Checking the options:

• A. Acetic acid: not a product of glycolysis. Acetyl-CoA forms later, when pyruvate is converted before the Krebs cycle.
• B. Citric acid: formed in the Krebs cycle, when acetyl-CoA combines with oxaloacetate.
• C. Ketoglutaric acid: an intermediate in the Krebs cycle.
• D. Oxaloacetic acid: also a Krebs cycle compound.
• E. Pyruvic acid: the end product of glycolysis. ✔

Answer: E. pyruvic acid

Tip: Remember "Glyco-lysis = glucose splitting → pyruvate." Everything else in the options (citric, ketoglutaric, oxaloacetic) belongs to the Krebs cycle, which happens later in the mitochondrion. If pyruvate is not oxygenated, it goes on to lactic acid or ethanol (fermentation) instead.