Which of These is a Male Sex Hormone?

Correct Answer: B

Rationale: The correct answer is B: Androgens. Androgens are male sex hormones responsible for male characteristics like facial hair growth and deepening of voice. Aldosterone (A) is a mineralocorticoid hormone, not a sex hormone. Pheromones (C) are chemical signals, not hormones. Insulin (D) is a hormone that regulates blood sugar levels, not related to sex characteristics. Therefore, B is the correct choice for a male sex hormone.

Correct Answer: C

Rationale: The correct answer is C: luminal acid. Gastrin secretion is primarily stimulated by the presence of luminal peptides and vagal discharge. Luminal acid inhibits gastrin secretion through negative feedback mechanisms. Phenylalanine does not directly stimulate gastrin secretion. In summary, luminal acid is the correct answer because it acts as an inhibitory factor for gastrin secretion, whereas the other choices are known stimulatory factors.

Correct Answer: D

Rationale: The correct answer is D. Folate absorption is not Na+ dependent because it is absorbed in the small intestine through a carrier-mediated process independent of sodium. Thiamin, riboflavin, and niacin require sodium-dependent transport mechanisms for absorption in the small intestine. Thiamin is absorbed through thiamin transporters that are Na+ dependent. Riboflavin is absorbed by sodium-dependent multivitamin transporters. Niacin absorption also involves sodium-dependent transporters. Therefore, folate is the only option that is not Na+ dependent for absorption.

Correct Answer: C

Rationale: Rationale for Choice C: Plasma norepinephrine levels are generally unchanged after adrenalectomy in the adrenal medulla because norepinephrine is mainly produced by postganglionic sympathetic nerve endings rather than the adrenal medulla. Adrenalectomy removes the adrenal gland, which primarily secretes epinephrine, not norepinephrine. Therefore, plasma norepinephrine levels would not be significantly affected by adrenalectomy. Summary of other choices: A: Incorrect. Epinephrine is formed from norepinephrine, not tyrosine, through methylation and hydroxylation. B: Incorrect. The majority of cells in the adrenal medulla are epinephrine-secreting cells, not just 10%. D: Incorrect. The half-life of catecholamines in the circulation is very short, around 2 minutes, not 10 minutes.

Correct Answer: B

Rationale: Correct Answer: B (GGP) Rationale: 1. CoA, ITP, and creatine phosphate are high-energy compounds involved in various metabolic processes. 2. GGP (guanosine-5'-triphosphate) is primarily a signaling molecule, not a high-energy compound. 3. CoA is involved in acetyl group transfer, ITP in energy transfer, and creatine phosphate in ATP regeneration. 4. GGP is a nucleotide involved in signaling pathways but does not directly participate in energy transfer reactions. Summary: - CoA, ITP, and creatine phosphate are high-energy compounds involved in energy transfer. - GGP is a signaling molecule and not classified as a high-energy compound.