Which of the following antibiotics inhibit the synthesis of the bacterial cell wall?

Correct Answer: C

Rationale: Cephalosporins inhibit the synthesis of the bacterial cell wall by binding to penicillin-binding proteins (PBPs), disrupting cell wall formation. They are beta-lactam antibiotics, similar to penicillins. Macrolides (A) inhibit bacterial protein synthesis, aminoglycosides (B) interfere with protein synthesis, and tetracyclines (D) inhibit protein synthesis by binding to the bacterial ribosome.

Correct Answer: A

Rationale: Passive diffusion involves movement of drug molecules across the cell membrane lipid layer from an area of high concentration to low concentration, without the need for energy or carrier proteins. Lipid-soluble drugs can easily diffuse through the lipid bilayer due to their hydrophobic nature. This process is driven by the concentration gradient and follows Fick's law of diffusion. Ion channels (B) facilitate the movement of ions, not drugs. Methyl residues (C) and transport proteins (D) are not directly involved in passive diffusion of drugs.

Correct Answer: A

Rationale: The correct answer is A: Amphetamine. Beta-blockers like Propranolol, Carvedilol, and Timolol work by blocking the effects of adrenaline on beta receptors, reducing heart rate and blood pressure. Amphetamine, on the other hand, is a stimulant drug that works by increasing the release of neurotransmitters like dopamine and norepinephrine, unrelated to beta receptor blockade. Therefore, Amphetamine is not a beta-blocker.

Correct Answer: C

Rationale: Certainly! Prazosin is an alpha-1 antagonist, which means it blocks the activation of alpha-1 adrenergic receptors. By blocking these receptors, prazosin leads to vasodilation and reduced peripheral vascular resistance, ultimately lowering blood pressure. The other options are not correct because prazosin does not act as a beta-1 antagonist (B), beta-2 agonist (D), or alpha-1 agonist (A) in the context of treating hypertension.

Correct Answer: B

Rationale: The correct answer is B: Increase of bronchial secretion. Parasympathetic stimulation activates the vagus nerve, leading to bronchial smooth muscle relaxation and increased secretion to facilitate breathing. This response helps in clearing the airways and optimizing gas exchange. Choices A, C, and D are incorrect because parasympathetic stimulation typically does not lead to an increase in intestinal motility (A), contraction of the iris sphincter muscle causing miosis (C), or a decrease in heart rate (D), as these are more characteristic of sympathetic stimulation.