All Free Veterinary Science MCQs with Answers

• A. Irreversible destruction of central receptors
• B. Permanent binding to plasma proteins
• C. Slow conversion into an inactive metabolite
• D. Rapid redistribution from the brain to other tissues

Explanation: After intravenous administration, propofol rapidly leaves the brain and redistributes into muscle and fat, causing recovery from the…

• A. Proton pump inhibitors
• B. Muscarinic agonists
• C. Loop diuretics
• D. Cholinesterase inhibitors

Explanation: Proton pump inhibitors such as omeprazole block the gastric hydrogen-potassium ATPase, the final step in acid secretion.

• A. It is always absorbed completely by mouth
• B. Toxic and effective concentrations are close together
• C. It cannot cross biological membranes
• D. Its elimination is independent of dose

Explanation: A narrow therapeutic index means that the toxic dose is close to the effective dose.

• A. Plasma protein binding
• B. Gastrointestinal absorption
• C. Hepatic biotransformation
• D. Tissue redistribution

Explanation: Hepatic biotransformation chemically modifies many lipid-soluble drugs, usually making them easier to eliminate in urine or bile.

• A. It produces no response at any dose
• B. It reduces the response of every unrelated receptor
• C. It permanently blocks the receptor
• D. It produces a submaximal response even at full receptor occupancy

Explanation: A partial agonist activates its receptor but has lower intrinsic efficacy than a full agonist, so its maximum response is limited.

• A. Xylazine
• B. Ketamine
• C. Acepromazine
• D. Diazepam

Explanation: Atipamezole is an alpha2 adrenergic antagonist that reverses sedation and other effects produced by xylazine and related alpha2 agonists.

• A. Nicotinic acetylcholine receptor
• B. N-methyl-D-aspartate receptor
• C. GABA-A receptor
• D. Mu opioid receptor

Explanation: Ketamine is a dissociative anaesthetic that mainly blocks N-methyl-D-aspartate receptors, reducing excitatory glutamate transmission.

• A. Lincosamides
• B. Macrolides
• C. Tetracyclines
• D. Sulfonamides

Explanation: Tetracyclines bind the 30S ribosomal subunit and prevent attachment of aminoacyl-tRNA, thereby inhibiting bacterial protein synthesis.

• A. Cuticular collagen
• B. Mitochondrial DNA
• C. Neuronal sodium channels
• D. Microtubules

Explanation: Benzimidazoles bind parasite beta-tubulin and disrupt microtubule formation, impairing nutrient uptake and cellular function.

• A. Phase II
• B. Phase I
• C. Phase III
• D. Phase zero

Explanation: Glucuronidation is a Phase II conjugation reaction that generally produces a more water-soluble metabolite.

• A. Enterohepatic recycling
• B. First-pass effect
• C. Zero-order elimination
• D. Volume displacement

Explanation: The first-pass effect is presystemic metabolism in the gut wall and liver after oral absorption, which reduces the amount reaching…

• A. A constant mass is eliminated per hour
• B. Elimination stops when concentration falls
• C. A constant fraction is eliminated per unit time
• D. Clearance increases without limit as dose rises

Explanation: In first-order kinetics, the amount eliminated per unit time depends on concentration, so a constant fraction is removed during each time…

• A. Naloxone
• B. Medetomidine
• C. Pentobarbital
• D. Acepromazine

Explanation: Acepromazine is a phenothiazine tranquilizer used for sedation and preanaesthetic medication, although it does not provide reliable…

• A. 50S subunit
• B. 40S subunit
• C. 30S subunit
• D. 60S subunit

Explanation: Chloramphenicol binds the 50S bacterial ribosomal subunit and inhibits peptidyl transferase activity.

• A. Highly soluble complexes
• B. Poorly absorbed chelates
• C. Rapidly hydrolysed esters
• D. Strongly acidic metabolites

Explanation: Tetracyclines bind calcium and form poorly absorbed chelates in the gastrointestinal tract.

• A. Muscarinic M2 receptor
• B. Beta-2 adrenergic receptor
• C. Alpha-1 adrenergic receptor
• D. Nicotinic Nn receptor

Explanation: Acepromazine blocks alpha-1 adrenergic receptors, producing peripheral vasodilation and possible hypotension.

• A. GABA-A receptor
• B. Histamine H1 receptor
• C. Opioid mu receptor
• D. Dopamine D2 receptor

Explanation: Metoclopramide mainly reduces vomiting through dopamine D2 receptor antagonism in the chemoreceptor trigger zone.

• A. Anticoagulant rodenticide
• B. Bromethalin rodenticide
• C. Cholecalciferol rodenticide
• D. Zinc phosphide rodenticide

Explanation: Vitamin K1 restores the production of functional clotting factors depleted by anticoagulant rodenticides.

• A. GABA chloride channels
• B. Nicotinic acetylcholine receptors
• C. Serotonin 5-HT1 receptors
• D. Muscarinic acetylcholine receptors

Explanation: Levamisole stimulates nematode nicotinic acetylcholine receptors, producing sustained contraction followed by paralysis.

• A. Cyclooxygenase
• B. Monoamine oxidase
• C. Phosphodiesterase
• D. Acetylcholinesterase

Explanation: Aminophylline, a theophylline preparation, inhibits phosphodiesterase and increases intracellular cyclic AMP, promoting bronchial smooth…