Ketosis and acidosis are:

Correct Answer: D

Rationale: The correct answer is D because ketosis and acidosis are indicative of a rapid and incomplete metabolism of fatty acids. Ketosis occurs when the body breaks down fats for energy, leading to high levels of ketones in the blood. Acidosis results from the accumulation of acidic substances in the body due to incomplete metabolism. Choices A, B, and C are incorrect because excess insulin does not cause ketosis and acidosis, diabetes insipidus is unrelated to these conditions, and ADH (antidiuretic hormone) is not the appropriate treatment for ketosis and acidosis.

Correct Answer: C

Rationale: The correct answer is C: Parathyroid hormone (PTH). The anterior pituitary gland secretes hormones that regulate various bodily functions, such as growth, reproduction, and metabolism. PTH is actually produced by the parathyroid glands, not the anterior pituitary. Human growth hormone (GH), follicle-stimulating hormone (FSH), and thyroid-stimulating hormone (TSH) are all hormones secreted by the anterior pituitary gland. Therefore, C is the correct answer as it is not a hormone produced by the anterior pituitary gland.

Correct Answer: C

Rationale: The correct answer is C: cAMP. Water-soluble hormones, such as adrenaline or glucagon, bind to cell surface receptors and activate a signaling cascade that often involves cAMP as a second messenger. Upon hormone binding, the receptor activates adenylyl cyclase, which converts ATP to cAMP. cAMP then activates protein kinase A, leading to phosphorylation of target proteins, ultimately affecting cellular responses. Explanation for incorrect choices: A: tRNA is involved in protein synthesis, not in signaling pathways of water-soluble hormones. B: ATP is used as an energy source in various cellular processes, but it is not a second messenger in hormone signaling pathways. D: PTH (parathyroid hormone) is a hormone involved in calcium regulation and does not act through cAMP signaling in the same manner as water-soluble hormones.

Correct Answer: D

Rationale: The correct answer is D: Follicle stimulating hormone. It stimulates the testes to produce sperm cells in males and promotes follicle development in females. Growth hormone (A) primarily regulates growth and metabolism. Leutenizing hormone (B) stimulates ovulation in females and testosterone production in males. Prolactin (C) is responsible for milk production in females.

Correct Answer: A

Rationale: The thymus gland is the correct answer because it involutes or shrinks with age, leading to decreased immune function. The parathyroid, thyroid, and pituitary glands do not disappear with old age but may undergo changes in function. The parathyroid regulates calcium levels, the thyroid controls metabolism, and the pituitary gland secretes various hormones. Therefore, the thymus gland is the only gland that disappears during old age, making it the correct answer.