MCQ Collection
MDCAT 2026 MCQs
Practice MDCAT 2026 questions with answers and explanations.
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Correct Answer: D. Plasma membrane
Explanation:
The plasma membrane is selectively permeable.
It regulates exchange between the cell and its environment.
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Correct Answer: D. Ribosome
Explanation:
Ribosomes translate mRNA into polypeptide chains.
They occur freely in cytoplasm or attached to rough ER.
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Correct Answer: D. Chloroplast
Explanation:
Chloroplasts contain chlorophyll and photosynthetic membranes.
They convert light energy into chemical energy.
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Correct Answer: A. Plasma membrane
Explanation:
The plasma membrane is selectively permeable.
It regulates exchange between the cell and its environment.
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Correct Answer: A. Synthesis and processing of secreted and membrane proteins
Explanation:
Rough ER has ribosomes attached to its surface.
It folds and modifies proteins entering the endomembrane system.
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Correct Answer: B. Phospholipid bilayer
Explanation:
Phospholipids form a bilayer with hydrophilic heads and hydrophobic tails.
Proteins and other molecules are embedded within it.
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Correct Answer: B. Synthesis and processing of secreted and membrane proteins
Explanation:
Rough ER has ribosomes attached to its surface.
It folds and modifies proteins entering the endomembrane system.
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Correct Answer: C. Phospholipid bilayer
Explanation:
Phospholipids form a bilayer with hydrophilic heads and hydrophobic tails.
Proteins and other molecules are embedded within it.
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Correct Answer: C. Synthesis and processing of secreted and membrane proteins
Explanation:
Rough ER has ribosomes attached to its surface.
It folds and modifies proteins entering the endomembrane system.
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Correct Answer: D. Phospholipid bilayer
Explanation:
Phospholipids form a bilayer with hydrophilic heads and hydrophobic tails.
Proteins and other molecules are embedded within it.
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Correct Answer: D. Lipid synthesis and detoxification
Explanation:
Smooth ER lacks ribosomes.
It synthesizes lipids and helps detoxify chemicals.
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Correct Answer: A. The dynamic arrangement of lipids and proteins in membranes
Explanation:
Membrane components can move laterally within the bilayer.
The membrane is flexible rather than rigid.