In males, what hormone is responsible for the development of secondary sexual characteristics?

Correct Answer: A

Rationale: The correct answer is A: Testosterone. Testosterone is the primary male sex hormone responsible for the development of secondary sexual characteristics such as facial hair, deepening of the voice, and muscle growth. It is produced by the testes in males. Estrogen (B) and Progesterone (C) are female sex hormones, while LH (D) is luteinizing hormone that stimulates the production of testosterone in males but is not responsible for the development of secondary sexual characteristics.

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 main function of the testes in males is to produce sperm. Sperm production, known as spermatogenesis, occurs within the seminiferous tubules of the testes. Testosterone is primarily secreted by the Leydig cells in the testes, not the main function. Storing sperm is not a primary function, as sperm is continuously produced and released. Transporting sperm is mainly done by the vas deferens, not the testes themselves. Therefore, the correct answer is B, as it directly relates to the primary function of the testes in males.

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.