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Two free, private review prompts. Choose an existing source, examine your own claims against specific excerpts, then return to its lesson or practice. No AI grading or automatic truth checking.
Changing the source or prompt clears this private draft. BB · When oxygen consumption and ATP production diverge · version 2026-10-13.1
MCAT science: distinguish the supplied observation, your inference and the teaching guidance. This review does not grade an answer or predict an exam score.
Read the supplied context before explaining
Supplied passage · paragraph 1
Original experimental reasoning passage. All compounds, measurements, and results below are constructed for practice; this is not a report of research.
Version 2026-10-13.1
Supplied passage · paragraph 2
A laboratory investigates how mitochondrial electron transport is coupled to ATP production. Electrons from fuel oxidation enter a chain of carriers and ultimately reduce oxygen. Several steps in the chain use released energy to move protons across the inner mitochondrial membrane. The resulting electrochemical gradient can drive proton return through ATP synthase, which couples that return to ATP formation. A large gradient also resists additional proton pumping. Thus, oxygen consumption and ATP formation are related but need not change in the same direction after every perturbation.
Version 2026-10-13.1
Supplied passage · paragraph 3
Researchers divide each of six independently prepared mitochondrial samples into four equal aliquots. Every aliquot receives the same amount of mitochondrial protein, a substrate that supplies electrons through entry site E, excess ADP and phosphate, and enough oxygen to avoid oxygen limitation. They add either vehicle or one of three experimental compounds. Each rate is measured during a short interval before the available substrate or ADP becomes limiting. A calibrated probe estimates the magnitude of the proton gradient; its reported signal increases as the gradient increases. The compounds do not directly interfere with the oxygen, ATP, or probe assays. The table reports constructed mean values, with each vehicle result normalized to 100 within its preparation. The gradient signal is an index, not a proton concentration or pH value.
Version 2026-10-13.1
Supplied passage · paragraph 4
In a second experiment, the investigators focus on compound A. They substitute an electron donor that feeds the chain downstream of E, leaving the rest of the assay unchanged. With this donor, oxygen-consumption rates are 96 units with vehicle and 92 units with A. This comparison is made using a common scale within the second experiment; it should not be used to calculate an ATP yield from the first experiment. ATP production is not measured in the second experiment.
Version 2026-10-13.1
Supplied passage · paragraph 5
A third experiment adds compound B to mitochondria already exposed to compound C. Oxygen consumption rises promptly, but ATP formation remains low. The researchers consider three simplified mechanisms: blocking electron entry at E, allowing protons to cross the membrane without passing through ATP synthase, and blocking proton passage through ATP synthase. For this exercise, assume each compound has one of these mechanisms and does not destroy the membrane or inhibit any other enzyme. The investigators have not tested intact cells, where fuel delivery, glycolysis, and feedback regulation could produce additional responses.
Version 2026-10-13.1
Constructed normalized means from the first experiment; vehicle = 100 for each measure
Condition | Oxygen consumption | ATP formation | Gradient signal Vehicle | 100 | 100 | 100 Compound A | 20 | 18 | 22 Compound B | 145 | 12 | 15 Compound C | 25 | 8 | 160
Version 2026-10-13.1
Separate my notes into claims and questions. For each, choose an exact excerpt from the selected source and version. Distinguish what the excerpt states from what I inferred. Record support, an apparent conflict, no relevant support, or uncertainty as my own provisional judgment. Keep unsupported claims unresolved. Choose one existing lesson or practice activity to revisit; do not invent facts or questions.
Fictional example — not a factual claim: My fictional explanation jumps from an observation to a cause. I have not stated which variable is held constant or what the supplied material actually supports.
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