Regarding protein metabolism, which statement is CORRECT?

Correct Answer: D

Rationale: The correct answer is D because creatinine excretion is not depressed in starvation. Creatinine is a byproduct of muscle metabolism and is relatively constant even during starvation when muscle breakdown occurs. A: Incorrect, as increasing respiratory quotient > 1.0 indicates excessive carbohydrate utilization. B: Incorrect, SDA is the energy used for digestion and absorption of nutrients, not specific to protein metabolism. C: Incorrect, glucagon stimulates protein breakdown to release amino acids for energy during fasting.

Correct Answer: B

Rationale: The correct answer is B: Gonads. Gonads are the primary reproductive organs, responsible for producing sex hormones and gametes. In males, the testes produce testosterone and sperm, while in females, the ovaries produce estrogen and eggs. Adrenal glands (A) produce hormones like cortisol and adrenaline, which are not sex-specific. Parathyroid glands (C) regulate calcium levels in the body. Pancreas (D) produces insulin and digestive enzymes, unrelated to sex differences. Therefore, the secretion from gonads is the only one that differs between males and females due to their distinct reproductive functions.

Correct Answer: C

Rationale: The correct answer is C: TSH (Thyroid Stimulating Hormone). The anterior pituitary gland secretes TSH, which stimulates the thyroid gland to produce thyroid hormones. This is a key hormone involved in regulating metabolism. A: ADH (Antidiuretic Hormone) is produced by the posterior pituitary gland. B: Oxytocin is also produced by the posterior pituitary gland and is involved in uterine contractions and lactation. D: Cortisol is produced by the adrenal glands, not the pituitary gland. In summary, TSH is the correct answer as it is the only hormone listed that is produced by the anterior pituitary gland.

Correct Answer: B

Rationale: The correct answer is B: Oesophagus. After swallowing, the food bolus passes through the pharynx and enters the oesophagus, a muscular tube that connects the mouth to the stomach. The oesophagus helps transport the bolus to the stomach for further digestion. The pharynx is a common pathway for both food and air, but the food should not enter the trachea (D) as it leads to the lungs, causing choking. The stomach (C) is the final destination for the food bolus after passing through the oesophagus.

Correct Answer: C

Rationale: The correct answer is C because during moments of danger, the adrenal gland secretes hormones like adrenaline and cortisol to prepare the body for a "fight or flight" response. These hormones increase heart rate and blood pressure to supply more oxygen and nutrients to the muscles, enabling the body to react quickly to the danger. Choices A, B, and D are incorrect because lowering metabolism, speeding up digestion, and decreasing heart rate and blood pressure are not adaptive responses to danger.