Which of the following is true of female sex hormones?

Correct Answer: B

Rationale: The correct answer is B because estrogen is indeed necessary for the maturation of the ovum. Estrogen promotes the development and release of the egg from the ovary during the menstrual cycle. This hormone is crucial for the growth of the follicles in the ovary and prepares the uterus for potential pregnancy. Rationale: A: Progesterone is responsible for maintaining the uterine lining during pregnancy, not for female secondary sex characteristics. C: Estrogen plays a significant role in breast development, so this statement is incorrect. D: Progesterone helps to prepare the uterus for pregnancy by promoting the growth of the uterine lining, not the uterus itself.

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.

Correct Answer: B

Rationale: Chief cells in the stomach secrete pepsinogen, which is the inactive precursor of pepsin, an enzyme that helps break down proteins. This is the correct answer because pepsinogen is the primary product secreted by chief cells. HCl is secreted by parietal cells, intrinsic factor is secreted by parietal cells in the stomach, and HCO3- is secreted by the pancreas to neutralize stomach acid in the duodenum.