Q38 - Diagnosing Electron Transport Chain Poisons from O2 Traces

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

Bioenergetics & Central Metabolism Overview

Peter Mitchell (1920-1992) discovered how mitochondria produce ATP. Electrons are harvested from succinate, malate and ascorbate (vitamin C), and drawn onto oxygen. Complexes I-IV sequentially harness their energy to pump protons across mitochondrial inner membranes (1). The oxygen saturation of a suspension of mitochondria, treated with substrates and the poisons potassium cyanide (KCN), rotenone or antimycin A (AA) at the indicated points, was measured over time (2).

Figure 1 for Q38: Diagnosing Electron Transport Chain Poisons from O2 Traces

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

A. Rotenone inhibits complex I.

B. Antimycin A inhibits cytochrome C.

C. Cyanide poisoning can be treated with malate.

D. Oxygen consumption is increased by poisons which introduce pores to mitochondrial membranes.

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Question reproduced from IBO 2017, Theoretical Exam B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions