Which of the following is least characteristic of the function of insulin?

Correct Answer: D

Rationale: The correct answer is D because insulin does not increase the generation of ketone bodies. Insulin actually inhibits ketogenesis by promoting glucose utilization and storage, preventing the breakdown of fats for energy. A, B, and C are all characteristics of insulin's function: A) Insulin increases glucose transport into the cell to lower blood glucose levels; B) It suppresses gluconeogenesis, the production of new glucose in the liver; C) Insulin lowers blood glucose levels by promoting the uptake and storage of glucose in cells.

Correct Answer: A

Rationale: The correct answer is A because glucagon stimulates the breakdown of glycogen into glucose, increasing blood glucose levels. Glucagon does not slow down glucose formation from lactic acid (B), decrease glycogen conversion (C), or speed up protein synthesis (D). Glucagon's primary function is to raise blood glucose levels in response to low blood sugar levels.

Correct Answer: B

Rationale: The correct answer is B: negative feedback system. In a negative feedback system, the body's response to a stimulus works to counteract the initial stimulus, bringing the body back to its set point. In the context of the question, hormone release stops when the stimulus is satisfied, which is characteristic of a negative feedback system. A: Positive feedback system amplifies the initial stimulus rather than counteracting it. C: Lock and key system refers to how enzymes bind to specific substrates, not related to hormone regulation. D: Solar system is unrelated to physiological processes.

Correct Answer: C

Rationale: The correct answer is C: Iodine. Iodine is essential for the production of thyroid hormones T3 and T4. These hormones regulate metabolism, growth, and development. Potassium (A), Sodium (B), and Calcium (D) do not play a direct role in thyroid function. Potassium and Sodium are electrolytes important for nerve function and fluid balance, while Calcium is crucial for bone health and muscle function. Therefore, the correct answer is Iodine as it is specifically required for normal thyroid function.

Correct Answer: D

Rationale: The correct answer is D: Both A & B. The thyroid and parathyroid glands work together to regulate calcium levels in the blood. The parathyroid gland releases parathyroid hormone, which increases calcium levels, while the thyroid gland secretes calcitonin, which decreases calcium levels. Therefore, both glands play a crucial role in maintaining calcium homeostasis. Choice A, the thyroid gland, is incorrect as it primarily regulates metabolism. Choice C, the adrenal medulla, is incorrect as it is responsible for releasing adrenaline and noradrenaline, not regulating calcium levels.