The main mineralocorticoid produced by the adrenal cortex is _____.

Correct Answer: D

Rationale: The correct answer is D: aldosterone. Aldosterone is the main mineralocorticoid produced by the adrenal cortex, responsible for regulating electrolyte balance and blood pressure. It acts on the kidneys to increase sodium reabsorption and potassium excretion. Cortisol (A) is a glucocorticoid, not a mineralocorticoid. Glucagon (B) is a hormone produced by the pancreas that raises blood glucose levels. Epinephrine (C) is a hormone produced by the adrenal medulla involved in the fight-or-flight response, not a mineralocorticoid. Therefore, the correct answer is aldosterone (D) due to its specific role in mineral balance regulation.

Correct Answer: B

Rationale: Correct Answer: B (FSH) Rationale: 1. FSH (Follicle Stimulating Hormone) is secreted by the anterior pituitary gland, not the hypothalamus. 2. PRH (Prolactin Releasing Hormone), CRH (Corticotropin Releasing Hormone), and TRH (Thyrotropin Releasing Hormone) are all hormones secreted by the hypothalamus, involved in regulating pituitary hormone release. 3. Therefore, FSH is the correct answer as it is not directly secreted by the hypothalamus. Summary: - FSH is secreted by the anterior pituitary gland, not the hypothalamus. - PRH, CRH, and TRH are hormones secreted by the hypothalamus. - Understanding the origin of each hormone helps in determining the correct answer.

Correct Answer: D

Rationale: The correct answer is D because hormones alter the activity of target tissues to regulate various physiological processes in the body. Hormones act on specific receptors in target tissues to initiate a response. Option A is incorrect because hormone levels fluctuate to maintain homeostasis. Option B is incorrect because hormones are typically synthesized by endocrine glands, not plasma proteins. Option C is incorrect because hormones are produced throughout life, not just after puberty.

Correct Answer: B

Rationale: The correct answer is B: B12. Vitamin B12 is water-soluble because it dissolves in water, allowing it to be easily absorbed and transported in the bloodstream. It plays a crucial role in nerve function, red blood cell production, and DNA synthesis. Vitamins D, A, and K are fat-soluble vitamins, meaning they are absorbed along with fats in the diet and are stored in the body's fat tissues. Since they are not water-soluble, they require bile for absorption and are stored in the body for longer periods. Hence, B12 is the only water-soluble vitamin among the given choices.

Correct Answer: B

Rationale: The correct answer is B because glucose, galactose, and fructose are transported across the basolateral membrane by the GLUT2 transporter. This occurs after they are absorbed into enterocytes through various transport mechanisms. Choice A is incorrect because SGLT-2 transporter is responsible for glucose and galactose absorption, not fructose. Choice C is incorrect as fructose is absorbed through facilitated diffusion, not secondary active transport. Choice D is incorrect because insulin actually increases carbohydrate absorption by upregulating GLUT2 expression.