Which of the following is the primary function of estrogen in the female reproductive system?

Correct Answer: C

Rationale: Estrogen's primary function is to stimulate the development of female secondary sexual characteristics such as breast development and widening of the hips. This is crucial for the maturation of the female reproductive system. Estrogen does not directly regulate ovulation (choice A), support pregnancy (choice B), or control the menstrual cycle (choice D). Ovulation is mainly regulated by luteinizing hormone and follicle-stimulating hormone, pregnancy is supported by progesterone, and the menstrual cycle is under the control of various hormones including estrogen and progesterone.

Correct Answer: B

Rationale: The correct answer is B: FSH. The pituitary gland produces follicle-stimulating hormone (FSH), which plays a key role in reproductive functions. FSH stimulates the growth and maturation of ovarian follicles in females and sperm production in males. A: Progesterone is produced by the ovaries and placenta in females. C: Estrogen is produced by the ovaries and adrenal glands in females. D: Testosterone is produced by the testes in males and in smaller amounts by the ovaries and adrenal glands in females.

Correct Answer: B

Rationale: The correct answer is B: Oxytocin. Oxytocin is the hormone responsible for stimulating the release of milk from the mammary glands. It acts by causing the contraction of the myoepithelial cells surrounding the alveoli in the breast, leading to the ejection of milk into the ducts. Estrogen (A) and FSH (D) are not directly involved in milk release. Prolactin (C) plays a role in milk production but not in the actual release of milk.

Correct Answer: B

Rationale: The correct answer is B: Oxytocin. Oxytocin is responsible for stimulating uterine contractions during labor. It is produced by the hypothalamus and released by the pituitary gland. Oxytocin acts on the smooth muscles of the uterus to initiate and regulate contractions, aiding in the progression of labor. Progesterone (A) helps maintain the uterine lining during pregnancy, while Prolactin (C) stimulates milk production. FSH (D) is a hormone that stimulates the growth and maturation of ovarian follicles in the ovaries.

Correct Answer: B

Rationale: The purpose of the zona pellucida during fertilization is to protect the egg during early development. It acts as a protective barrier around the egg, preventing polyspermy and providing structural support for the developing embryo. This choice is correct because the zona pellucida serves as a crucial protective layer for the egg in the initial stages post-fertilization. - A: Incorrect because the zona pellucida actually allows sperm entry into the egg. - C: Incorrect because the zona pellucida does not specifically facilitate sperm entry; its primary function is protection. - D: Incorrect because the zona pellucida is not directly involved in egg implantation, but rather in early embryonic development.