A deficiency of dietary iodine:

Correct Answer: D

Rationale: The correct answer is D because a deficiency of dietary iodine leads to an insufficient production of thyroid hormones, which can result in the enlargement of the thyroid gland, known as a goiter. This is due to the thyroid gland working harder to try to produce more hormones. A, B, and C are incorrect because a deficiency of dietary iodine does not directly affect plasma calcium levels, blood volume, or the synthesis of calcitonin. These are functions that are primarily regulated by other hormones and factors in the body, not by iodine deficiency.

Correct Answer: B

Rationale: The correct answer is B because a hormone that suppresses gluconeogenesis helps to prevent hyperglycemia by inhibiting the production of glucose in the liver. This hormone regulates blood sugar levels by reducing the formation of new glucose molecules. Choice A is incorrect because increasing renal excretion of sodium and water is related to the regulation of fluid balance, not gluconeogenesis. Choice C is incorrect because causing diuresis involves increasing urine production and is not directly related to suppressing gluconeogenesis. Choice D is incorrect because causing hypocalcemia refers to low levels of calcium in the blood and is not associated with the suppression of gluconeogenesis.

Correct Answer: C

Rationale: The correct answer is C: beta cells. Beta cells in the pancreas secrete insulin, which helps decrease blood glucose levels by facilitating the uptake of glucose into cells for energy production. Delta cells (choice A) secrete somatostatin, which inhibits insulin and glucagon secretion. Alpha cells (choice B) secrete glucagon, which increases blood glucose levels. Choice D is a duplicate of choice C. Therefore, the correct answer is C as beta cells play a crucial role in regulating blood glucose levels through insulin secretion.

Correct Answer: C

Rationale: The correct answer is C, Gnadocorticoids, such as the androgens. The adrenal glands produce androgens like DHEA which can supplement sex hormones from the gonads. Choice A, mineralocorticoids, control electrolyte and water balance. Choice B, glucocorticoids, regulate metabolism and immune response. Choice D, epinephrine and norepinephrine, are involved in the fight or flight response. Gnadcorticoids, specifically androgens, are the hormones from the adrenal glands that can supplement sex hormones from the gonads, making choice C the correct answer.

Correct Answer: B

Rationale: The correct answer is B because exocrine glands secrete their products through ducts out onto the skin or into body cavities, unlike endocrine glands that release hormones directly into the bloodstream. This distinction is crucial as exocrine glands do not release hormones into the blood (A), do not necessarily affect many body organs (C), and are not limited to the reproductive organs (D). The unique characteristic of exocrine glands secreting through ducts sets them apart from endocrine glands.