Q12 - Determining Metabolic Pathway and ATP Yield from Gas Exchange in Yeast

Theoretical 2 Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Bioenergetics & Central Metabolism Overview

Yeast can metabolize glucose using aerobic respiration (C6H12O6 + 6O2 -> 6CO2 + 6H2O, 32 ATP) and alcohol fermentation (C6H12O6 -> 2C2H5OH + 2CO2, 2 ATP) depending on environmental conditions. Yeast was cultured in a glucose solution under conditions A and B, and gas inflow and outflow from the incubator were measured: Condition A: O2 absorption 0 mL, CO2 emission 20 mL. Condition B: O2 absorption 30 mL, CO2 emission 40 mL. (Assume the same amount of glucose was completely metabolized under conditions A and B.)

Using the information and data, determine which of the statements are true or which are false.

Q12-1 Condition A. How was glucose metabolized under condition A?

Q12-1 Condition B. How was glucose metabolized under condition B?

Q12-2. Assuming that 100 equivalents of ATP were generated under condition A, how many equivalents of ATP were generated under condition B?

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Question reproduced from IBO 2020, Theoretical Exam 2, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)