Sources of human insulin production are:

Correct Answer: C

Rationale: The correct answer is C: All of the above. Recombinant DNA techniques involve inserting the proinsulin gene into E. coli or yeast to produce human insulin. This is a common method used in commercial insulin production. Postmortem insulin extraction from human autopsy pancreas is also a valid source of human insulin, although it is less common due to ethical and practical considerations. Therefore, both A and B are valid sources of human insulin production, making option C the correct choice. Option D is incorrect because we have established that both A and B are valid methods for human insulin production.

Correct Answer: B

Rationale: Step-by-step rationale for choice B (Cyproheptadine) as the correct answer: 1. Cyproheptadine is a potent H1 receptor antagonist. 2. It is also known for its significant serotonin-blocking effect. 3. This dual mechanism of action makes it effective for treating conditions involving both histamine and serotonin imbalances. 4. Brompheniramine (A), Suprastine (C), and Dimedrol (D) do not exhibit significant serotonin-blocking effects, making them incorrect choices.

Correct Answer: A

Rationale: The correct answer is A: Extreme dryness of the conjunctiva resulting from a disease localized in the eye or from systemic deficiency of vitamin A. Xerophthalmia refers to extreme dryness of the eyes due to vitamin A deficiency. It affects the conjunctiva, leading to dry eyes. This condition can be localized in the eye or due to systemic deficiency of vitamin A. Choice B is incorrect because it describes a condition known as keratomalacia, which involves softening, ulceration, and perforation of the cornea, not extreme dryness of the conjunctiva. Choice C is also incorrect as it describes night blindness, a condition where vision is weak in dim light due to vitamin A deficiency, not extreme dryness of the conjunctiva. Choice D is incorrect because it includes all the statements, but xerophthalmia specifically refers to extreme dryness of the conjunctiva due to vitamin A deficiency, not the other conditions mentioned.

Correct Answer: A

Rationale: Hypercholesterolemia is indeed an abnormally high concentration of cholesterol in the blood, making choice A true. Choice B is incorrect as hypercholesterolemia is a recognized medical condition. Choice C, stating "All," is incorrect as it is too vague and does not provide a clear answer. Choice D, stating "None," is also incorrect because hypercholesterolemia is a valid medical term and condition.

Correct Answer: D

Rationale: The correct answer is D because the metabolic products of probenecid are not uricosuric. Probenecid itself is uricosuric, meaning it promotes the excretion of uric acid from the body by inhibiting its reabsorption in the kidney tubules. Choice A is correct as probenecid does indeed promote the renal tubular secretion of penicillin. Choice B is correct as probenecid is used in the treatment of gout by lowering uric acid levels in the blood. Choice C is correct as probenecid, at appropriate doses, promotes the excretion of uric acid, thereby helping to manage conditions like gout.