MCQ Collection
MDCAT 2026 MCQs
Practice MDCAT 2026 questions with answers and explanations.
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Correct Answer: C. To convert light energy into chemical energy
Explanation:
Photosynthesis builds carbohydrates from carbon dioxide and water.
Light energy is captured by pigments such as chlorophyll.
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Correct Answer: D. To convert light energy into chemical energy
Explanation:
Photosynthesis builds carbohydrates from carbon dioxide and water.
Light energy is captured by pigments such as chlorophyll.
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Correct Answer: A. To transfer energy from organic molecules into ATP
Explanation:
Cellular respiration oxidizes fuel molecules.
Most ATP in aerobic cells is produced through oxidative phosphorylation.
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Correct Answer: B. To transfer energy from organic molecules into ATP
Explanation:
Cellular respiration oxidizes fuel molecules.
Most ATP in aerobic cells is produced through oxidative phosphorylation.
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Correct Answer: C. Mitochondrial matrix
Explanation:
The Krebs cycle oxidizes acetyl-CoA.
It produces reduced electron carriers and carbon dioxide.
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Correct Answer: D. An inhibitor competes with substrate for the active site
Explanation:
Competitive inhibitors resemble or obstruct the substrate.
Their effect can often be reduced by increasing substrate concentration.
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Correct Answer: A. An inhibitor competes with substrate for the active site
Explanation:
Competitive inhibitors resemble or obstruct the substrate.
Their effect can often be reduced by increasing substrate concentration.
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Correct Answer: B. A biological catalyst
Explanation:
Enzymes lower activation energy.
They speed reactions without being consumed overall.
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Correct Answer: B. An inhibitor competes with substrate for the active site
Explanation:
Competitive inhibitors resemble or obstruct the substrate.
Their effect can often be reduced by increasing substrate concentration.
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Correct Answer: C. A biological catalyst
Explanation:
Enzymes lower activation energy.
They speed reactions without being consumed overall.
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Correct Answer: C. An inhibitor binds away from the active site and changes enzyme activity
Explanation:
Noncompetitive binding changes enzyme shape or function.
Adding more substrate does not fully overcome it.
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Correct Answer: D. Region where the substrate binds and reaction occurs
Explanation:
The active site has a shape and chemistry suited to its substrate.
Binding promotes the transition state.
