MCQ Collection
Biology MCQs
Practice Biology questions with answers and explanations.
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Correct Answer: B. Memory lymphocytes enable a faster and stronger response after re-exposure to an antigen
Explanation:
Adaptive immunity forms antigen-specific memory cells, the basis of vaccination.
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Correct Answer: A. Energy decreases between trophic levels because much is lost as heat and metabolic work
Explanation:
Matter cycles, but usable energy flows through ecosystems and declines at successive trophic levels.
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Correct Answer: D. Energy decreases between trophic levels because much is lost as heat and metabolic work
Explanation:
Matter cycles, but usable energy flows through ecosystems and declines at successive trophic levels.
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Correct Answer: D. Allele frequencies can change through selection, drift, mutation and gene flow
Explanation:
Several evolutionary forces alter allele frequencies; drift is especially influential in small populations.
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Correct Answer: C. The phospholipid bilayer is selectively permeable and contains functional proteins
Explanation:
Cell membranes are phospholipid bilayers with proteins that regulate transport and signalling.
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Correct Answer: A. Mitosis produces daughter nuclei with the same chromosome number as the parent nucleus
Explanation:
Mitosis preserves chromosome number and supports growth and tissue repair.
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Correct Answer: D. Meiosis reduces chromosome number and creates variation through independent assortment and recombination
Explanation:
Meiosis forms haploid cells and generates variation through chromosome segregation and recombination.
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Correct Answer: C. Each new DNA molecule contains one parental strand and one newly synthesised strand
Explanation:
DNA replication is semiconservative and uses complementary base pairing.
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Correct Answer: B. Enzymes lower activation energy without being consumed by the reaction
Explanation:
Enzymes catalyse reactions by lowering activation energy; conditions influence their structure and rate.
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Correct Answer: A. Light reactions generate ATP and reducing power used in carbon fixation
Explanation:
Light reactions provide ATP and NADPH, while the Calvin cycle fixes carbon into organic molecules.
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Correct Answer: B. Heritable traits that improve reproductive success can become more common across generations
Explanation:
Natural selection changes population trait frequencies when heritable variation affects reproductive success.
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Correct Answer: D. Negative feedback counteracts deviations from a physiological set range
Explanation:
Negative-feedback systems detect deviations and activate responses that restore a regulated range.
