Q12. A laboratory worker accidentally inhales fumes of an oxidative phosphorylation uncoupling agent. Which of the following physiological changes is most likely to occur?

Appeared in: INI-CET EXAM -2026

Explanation

Uncoupling agents separate the electron transport chain (oxidation) from ATP synthesis (phosphorylation).
They create a pathway for protons to bypass ATP synthase, causing the energy of the proton gradient to be released as heat, which increases body temperature.
Because protons are not driving ATP synthase, ATP production decreases significantly.
The body attempts to compensate for the low ATP levels by accelerating the electron transport chain, which dramatically increases the consumption of oxygen.

Option A: This option incorrectly states that O2 consumption decreases and ATP production increases. In reality, the body's compensatory mechanism increases O2 consumption, and the uncoupling action prevents ATP synthesis.
Option C: This option incorrectly states that body temperature decreases and ATP production increases. The energy from the dissipated proton gradient is released as heat, causing hyperthermia (increased temperature), and ATP production is halted.
Option D: This option incorrectly states that O2 consumption and body temperature decrease. The opposite occurs; the ETC goes into overdrive, increasing O2 consumption, and the wasted energy is released as heat, increasing body temperature.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiological effects of oxidative phosphorylation uncoupling agents as background academic context rather than a clinical decision trigger.
Classic examples of uncouplers include 2,4-dinitrophenol (DNP), once illicitly used as a weight-loss drug, and high doses of aspirin (salicylates).
Clinically, a patient with uncoupler poisoning presents with hyperthermia (fever), tachycardia, tachypnea (rapid breathing), and profuse sweating as the body tries to dissipate the excess heat.
Nursing management is primarily supportive and focuses on aggressive cooling measures (e.g., cooling blankets, ice packs), hydration, and monitoring vital signs and acid-base balance.

How to Approach the Question

First, identify the key term: 'oxidative phosphorylation uncoupling agent'.
Recall the core function of these agents: they 'uncouple' or separate two linked processes: the electron transport chain (which uses oxygen) and ATP synthesis.
Think through the consequences of this uncoupling: The proton gradient energy, which normally powers ATP synthesis, is now wasted and released as heat. This means body temperature must increase.
Since the protons are bypassing ATP synthase, the production of ATP must decrease.
The cell senses the low ATP levels and tries to compensate by running the electron transport chain at maximum speed. This requires a massive amount of oxygen, so O2 consumption must increase.
Finally, find the option that matches this triad of effects: Increased O2 consumption, Increased body temperature, and Decreased ATP production.

Concept Tested & Keywords

Concept Tested: Physiological effects of oxidative phosphorylation uncoupling agents
Stem keywords: oxidative phosphorylation, uncoupling agent, physiological changes
Lead-in keywords: most likely to occur
Negative lead-in flag: false

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E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 135-137

E6 Biochemistry U Satyanarayana— Part 1 (pp 26-420 of 840) p. 226-228

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