Practice Library
All MCQs
Browse exam-wise, subject-wise, and country-wise MCQs with explanations.
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A.
Antibiotics deliberately teach each bacterium to resist
B.
Antibiotic exposure can select resistant organisms already carrying or acquiring resistance determinants
C.
Resistance has no genetic basis
D.
Stopping all infection control prevents resistance
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Correct Answer: B. Antibiotic exposure can select resistant organisms already carrying or acquiring resistance determinants
Explanation:
Selection favours resistant variants, while transmission and gene exchange can spread resistance.
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A.
A reversible competitive antagonist shifts an agonist concentration-response curve to the right without reducing maximal response when enough agonist is available
B.
A reversible competitive antagonist necessarily lowers the maximal response even when much higher agonist concentrations are available
C.
A competitive antagonist increases agonist potency by shifting the concentration-response curve left while leaving receptor occupancy unchanged
D.
An irreversible antagonist permanently occupies receptors, so increasing agonist concentration fully restores the original maximal response
Show Answer
Correct Answer: A. A reversible competitive antagonist shifts an agonist concentration-response curve to the right without reducing maximal response when enough agonist is available
Explanation:
Competition at the same receptor can be overcome by higher agonist concentration, reducing apparent potency but not efficacy.
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A.
Clearance relates elimination rate to drug concentration and helps determine maintenance dosing
B.
Clearance has no relationship to elimination
C.
Maintenance dosing depends only on tablet colour
D.
Clearance is the same as absorption fraction
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Correct Answer: A. Clearance relates elimination rate to drug concentration and helps determine maintenance dosing
Explanation:
Systemic clearance describes the effective volume cleared per unit time and links concentration to elimination rate.
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A.
Tumours are unrelated to selection among cell clones
B.
A single mutation always produces invasive cancer immediately
C.
Cancer develops through accumulated alterations affecting growth control, survival, repair and the tissue environment
D.
DNA repair has no relevance to cancer risk
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Correct Answer: C. Cancer develops through accumulated alterations affecting growth control, survival, repair and the tissue environment
Explanation:
Tumorigenesis is multistep and reflects genetic, epigenetic and microenvironmental selection.
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A.
Acute inflammation never recruits leukocytes
B.
Inflammatory mediators coordinate vascular change, leukocyte recruitment and local symptoms
C.
All mediators have identical effects
D.
Inflammation occurs without signalling molecules
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Correct Answer: B. Inflammatory mediators coordinate vascular change, leukocyte recruitment and local symptoms
Explanation:
Multiple mediators act on vessels, cells and tissues to produce the organised inflammatory response.
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A.
Compensation changes the other component of the bicarbonate-carbon dioxide system but does not remove the primary disorder
B.
The kidneys cannot affect acid-base balance
C.
The lungs regulate bicarbonate directly as their main action
D.
Compensation always overshoots to the opposite pH disorder
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Correct Answer: A. Compensation changes the other component of the bicarbonate-carbon dioxide system but does not remove the primary disorder
Explanation:
Respiratory and renal responses limit pH change while the primary process remains identifiable.
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A.
Stroke volume is unrelated to venous return
B.
Afterload can never influence ejection
C.
Cardiac output equals blood pressure divided by temperature
D.
Cardiac output equals heart rate multiplied by stroke volume and changes with preload, contractility and afterload
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Correct Answer: D. Cardiac output equals heart rate multiplied by stroke volume and changes with preload, contractility and afterload
Explanation:
Cardiac output integrates rate and stroke volume, while loading conditions and contractility influence stroke volume.
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A.
Transport proteins cannot be selective
B.
Diffusion moves every solute against its gradient
C.
Net passive transport follows an electrochemical gradient and does not directly consume ATP
D.
All membrane transport directly hydrolyses ATP
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Correct Answer: C. Net passive transport follows an electrochemical gradient and does not directly consume ATP
Explanation:
Passive transport is driven by concentration and electrical gradients, although channels or carriers may facilitate it.
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A.
Random error and bias are identical
B.
Bias is eliminated automatically by a large sample
C.
Measurement methods cannot introduce systematic error
D.
Bias is a systematic error in selection, measurement or analysis that can distort an estimated association
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Correct Answer: D. Bias is a systematic error in selection, measurement or analysis that can distort an estimated association
Explanation:
Larger samples reduce random error but do not necessarily correct systematic design or measurement problems.
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A.
Cytokines cannot influence cell differentiation
B.
Specific lymphocytes activate without any signal
C.
Antigen recognition plus appropriate co-stimulation and cytokine signals shape lymphocyte activation and differentiation
D.
Co-stimulation is irrelevant to immune tolerance
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Correct Answer: C. Antigen recognition plus appropriate co-stimulation and cytokine signals shape lymphocyte activation and differentiation
Explanation:
Adaptive responses integrate receptor specificity with co-stimulatory and environmental signals.
Choose an option to check your answer.
A.
Antibiotic exposure can select resistant organisms already carrying or acquiring resistance determinants
B.
Resistance has no genetic basis
C.
Antibiotics deliberately teach each bacterium to resist
D.
Stopping all infection control prevents resistance
Show Answer
Correct Answer: A. Antibiotic exposure can select resistant organisms already carrying or acquiring resistance determinants
Explanation:
Selection favours resistant variants, while transmission and gene exchange can spread resistance.
Choose an option to check your answer.
A.
An irreversible antagonist permanently occupies receptors, so increasing agonist concentration fully restores the original maximal response
B.
A competitive antagonist increases agonist potency by shifting the concentration-response curve left while leaving receptor occupancy unchanged
C.
A reversible competitive antagonist shifts an agonist concentration-response curve to the right without reducing maximal response when enough agonist is available
D.
A reversible competitive antagonist necessarily lowers the maximal response even when much higher agonist concentrations are available
Show Answer
Correct Answer: C. A reversible competitive antagonist shifts an agonist concentration-response curve to the right without reducing maximal response when enough agonist is available
Explanation:
Competition at the same receptor can be overcome by higher agonist concentration, reducing apparent potency but not efficacy.
