Concerning catecholamines, all the following are true EXCEPT:

Correct Answer: D

Rationale: The correct answer is D because ephedrine and amphetamine are not catecholamines. A is correct as catecholamines contain a catechol nucleus. B is true as they act directly on receptors. C is also true since catecholamines have a short duration of action. Therefore, D is the incorrect statement as ephedrine and amphetamine do not fall under the category of catecholamines due to their chemical structure and mode of action.

Correct Answer: C

Rationale: The correct answer is C: Amitriptyline. Amitriptyline is a tricyclic antidepressant known for its anticholinergic properties, causing dry mouth, constipation, blurred vision, and urinary retention. Anticholinergic effects result from blocking the action of acetylcholine in the parasympathetic nervous system. Codeine (A) is an opioid, Ciprofloxacin (B) is an antibiotic, and Propranolol (D) is a beta-blocker, none of which are expected to cause significant anticholinergic effects.

Correct Answer: D

Rationale: The correct answer is D because organophosphate insecticides and nerve gases inhibit acetylcholine metabolism by irreversibly binding to acetylcholinesterase enzyme, leading to accumulation of acetylcholine at synapses. This results in overstimulation of cholinergic receptors, causing symptoms of cholinergic toxicity. Choice A is incorrect because alpha and beta-adrenergic receptors are not the targets of organophosphates. Choice B is incorrect because organophosphates do not block all muscarinic receptors. Choice C is incorrect because organophosphates do not specifically target nicotinic receptors in the brain.

Correct Answer: D

Rationale: The correct answer is D: scurvy. Scurvy is caused by a deficiency of vitamin C, leading to symptoms such as fatigue, bleeding gums, and skin discoloration. Vitamin C is essential for collagen synthesis, and its deficiency impairs collagen formation. A: AIDS is caused by the human immunodeficiency virus (HIV), not by a lack of vitamin C. B: Coronary heart disease is primarily related to factors such as high cholesterol, high blood pressure, and smoking, not vitamin C deficiency. C: Rickets is caused by a deficiency of vitamin D, leading to soft and weak bones, not by a lack of vitamin C.

Correct Answer: D

Rationale: The correct answer is D because lead is the product at the cathode (negative electrode) during electrolysis, while bromine is the product at the anode (positive electrode). Lead is reduced at the cathode to form lead metal, and bromine is oxidized at the anode to form bromine gas. This is in line with the general rule that cations are attracted to the cathode and are reduced, while anions are attracted to the anode and are oxidized. Choice A is incorrect as bromide ions are reduced at the cathode, not lead ions. Choice B is incorrect because bromine is produced at the anode, not lead. Choice C is incorrect because lead ions are reduced at the cathode, not bromide ions.