Deficiency symptom of vitamin A is:

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Vitamin A deficiency can lead to various symptoms, including night blindness (choice A), xerophthalmia and keratomalacia (choice B), and various epithelial tissue defects that can result in decreased resistance to infective diseases, male and female infertility (choice C). These symptoms occur due to the role of vitamin A in maintaining healthy vision, skin, and mucous membranes. Therefore, choosing option D is correct as it encompasses all the possible deficiency symptoms associated with vitamin A deficiency.

Correct Answer: A

Rationale: Allopurinol is the correct answer as it inhibits xanthine oxidase, an enzyme involved in uric acid synthesis. By reducing the conversion of hypoxanthine to xanthine and xanthine to uric acid, allopurinol effectively lowers uric acid levels. Sulfinpyrazone increases uric acid excretion, not synthesis. Colchicine works by reducing inflammation in gout attacks, not affecting uric acid levels. Indomethacin is a nonsteroidal anti-inflammatory drug that alleviates gout symptoms but does not target uric acid synthesis.

Correct Answer: B

Rationale: Step-by-step rationale: 1. Calcium administration is indicated in malabsorption of vitamin D because vitamin D is necessary for calcium absorption in the intestine. 2. Malabsorption of vitamin D leads to decreased calcium absorption, which can result in calcium deficiency. 3. Administering calcium can help compensate for the decreased absorption of calcium due to vitamin D malabsorption. Summary: - Option A is incorrect as the formation of vitamin D in the skin is not directly related to calcium administration. - Option C is incorrect as hypercalcemia of malignancy indicates excess calcium, not a need for calcium administration. - Option D is incorrect as it mentions the deficiency of vitamin D, not the malabsorption of vitamin D, which is the indication for calcium administration.

Correct Answer: B

Rationale: The correct answer is B: Ascending thick limb of the loop of Henle. Furosemide inhibits the Na+/K+/2Cl- symporter in this nephron segment, leading to decreased reabsorption of sodium, chloride, and water. This mechanism of action results in increased diuresis. The other choices (A, C, D) represent different nephron segments where Furosemide does not primarily act. In the proximal convoluted tubule (A), it mainly inhibits the Na+/K+/2Cl- symporter, and in the distal convoluted tubule (C) and collecting duct (D), it has minimal impact on sodium reabsorption.

Correct Answer: D

Rationale: Step-by-step rationale for why answer D is correct: 1. Vancomycin is a glycopeptide antibiotic known to inhibit cell wall synthesis. 2. It is effective against Gram-positive bacteria such as Staphylococcus and Streptococcus. 3. Vancomycin is not active against Gram-negative bacteria due to differences in cell wall structure. 4. Options A, B, and C are incorrect as they provide inaccurate information about vancomycin's characteristics.