The statement, that some microorganisms can develop alternative metabolic pathways for rendering reactions inhibited by the drug, is:

Correct Answer: A

Rationale: The correct answer is A: TRUE. Some microorganisms can indeed develop alternative metabolic pathways to bypass the inhibition caused by a drug. This is a common phenomenon known as drug resistance in microbial populations. Other choices are incorrect: B is false because drug resistance through alternative pathways is a known fact; C (All) is incorrect as not all microorganisms exhibit this behavior; and D (None) is incorrect as some microorganisms do develop alternative pathways to counter drug inhibition.

Correct Answer: A

Rationale: The correct answer is A: Metronidazole and diloxanide. Metronidazole is effective against the invasive form of Entamoeba histolytica, the parasite causing amebiasis. Diloxanide is used to eliminate the non-invasive cyst form of the parasite in the intestine. Streptomycin (choice B) is not effective against amebiasis. Iodoquinol (choice C) is used for non-invasive amebiasis but not the intestinal form. Emetine (choice D) is reserved for extraintestinal disease and is not commonly used due to its toxicity.

Correct Answer: B

Rationale: Fluorouracil is an antimetabolite that interferes with DNA and RNA synthesis. It is used to treat various cancers by inhibiting cell growth. This makes option B the correct choice. Antibiotics (A) target bacteria, not cancer cells. Plant alkaloids (C) are derived from plants and have different mechanisms of action. Bone marrow growth factors (D) stimulate the production of blood cells but do not directly inhibit cancer cell growth.

Correct Answer: B

Rationale: The correct answer is B: Verapamil. Verapamil is a calcium channel blocker that acts on acetylcholine-sensitive K+ channels, leading to smooth muscle relaxation and vasodilation. Digoxin (A) acts on cardiac muscle by inhibiting the sodium-potassium pump. Propranolol (C) is a beta-blocker that acts on beta-adrenergic receptors. Procainamide (D) is a Class I antiarrhythmic agent that blocks sodium channels. Thus, Verapamil is the correct choice based on its mechanism of action on acetylcholine-sensitive K+ channels.

Correct Answer: B

Rationale: The correct answer is B: Add nitroglycerin to the therapeutic regimen. Nitroglycerin is a standard treatment for variant angina as it helps dilate blood vessels, increasing blood flow to the heart. This can help relieve chest pain associated with the condition. Choice A is incorrect as nifedipine and propranolol are both used to treat angina, but nifedipine is not specifically indicated for variant angina. Choice C is incorrect as captopril is an ACE inhibitor used for hypertension and heart failure, not specifically for variant angina. Choice D is incorrect as nifedipine and hydrochlorothiazide are both used for hypertension but not specifically for variant angina.