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Q18 - Lactic Acid Fermentation

Theoretical 2 Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license
Bioenergetics & Central Metabolism Overview

The process of lactic acid fermentation, the conversion of a glucose molecule into two molecules of lactic acid (lactate), is schematically presented below.

Numbers SI–SV indicate unidentified substances I–V involved in this process.

Lactic acid fermentation pathway diagram showing glucose to pyruvate to lactate, with substances SI through SV at various steps

True or False?

Q18.1. All substances (SI-SV) on the scheme are organic substances.
Q18.2. The process shown on the scheme proceeds at a high rate in many types of cancer cells.
Q18.3. In aerobic eukaryotic cells, the substance SI can be synthesized at a high rate in mitochondria.
Q18.4. The last reaction in this process (pyruvate to lactate) is needed for the reduction of the substance SIV.
Q18.5. Many yeasts, for example S. cerevisiae, use this process in carbohydrate metabolism under anaerobic conditions.
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Question reproduced from IBO 2023, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF