MCQ Collection
MDCAT 2026 MCQs
Practice MDCAT 2026 questions with answers and explanations.
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Correct Answer: B. Cytoplasm
Explanation:
Glycolysis breaks glucose into pyruvate.
It occurs in the cytosol and does not directly require oxygen.
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Correct Answer: C. Activity rises to an optimum and then may fall as the enzyme denatures
Explanation:
Warming increases molecular collisions up to an optimum.
Excess heat disrupts enzyme structure.
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Correct Answer: C. Cytoplasm
Explanation:
Glycolysis breaks glucose into pyruvate.
It occurs in the cytosol and does not directly require oxygen.
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Correct Answer: D. Activity rises to an optimum and then may fall as the enzyme denatures
Explanation:
Warming increases molecular collisions up to an optimum.
Excess heat disrupts enzyme structure.
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Correct Answer: D. 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: A. Each enzyme has an optimal pH range
Explanation:
PH alters ionization of amino-acid side chains.
Extreme pH can reduce activity or denature enzymes.
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Correct Answer: B. Each enzyme has an optimal pH range
Explanation:
PH alters ionization of amino-acid side chains.
Extreme pH can reduce activity or denature enzymes.
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Correct Answer: C. Each enzyme has an optimal pH range
Explanation:
PH alters ionization of amino-acid side chains.
Extreme pH can reduce activity or denature enzymes.
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Correct Answer: D. Loss of normal protein shape and function
Explanation:
Heat, pH, or chemicals can disrupt protein folding.
The amino-acid sequence may remain intact.
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Correct Answer: A. A biological catalyst
Explanation:
Enzymes lower activation energy.
They speed reactions without being consumed overall.
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Correct Answer: A. A lipid with a hydrophilic head and hydrophobic tails
Explanation:
Phospholipids spontaneously form bilayers in water.
They are the main structural molecules of cell membranes.
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Correct Answer: B. A lipid with a hydrophilic head and hydrophobic tails
Explanation:
Phospholipids spontaneously form bilayers in water.
They are the main structural molecules of cell membranes.
