What area experiences the greatest changes in a menstrual cycle?

Correct Answer: D

Rationale: The correct answer is D: endometrium. The endometrium undergoes the most significant changes during the menstrual cycle. It thickens and sheds in response to hormonal changes for potential implantation of a fertilized egg. The vagina (A), perimetrium (B), and cervix (C) do not experience the same level of cyclic changes as the endometrium. The vagina is primarily a passageway, the perimetrium is the outer layer of the uterus, and the cervix mainly functions as an opening to the uterus. Therefore, the endometrium is the area that experiences the greatest changes in a menstrual cycle due to its role in preparing for possible pregnancy and shedding if implantation does not occur.

Correct Answer: C

Rationale: The correct answer is C: Digestive enzymes. The acrosome is a specialized organelle found in the head of sperm cells and is filled with enzymes that are crucial for fertilization. These enzymes help the sperm penetrate the outer layers of the egg during fertilization. Choice A (Lipids) is incorrect because the acrosome primarily contains enzymes, not lipids. Choice B (Hormones) is incorrect as hormones are not stored in the acrosome. Choice D (None of the above) is incorrect as the acrosome does indeed contain digestive enzymes essential for the sperm's fertilization process.

Correct Answer: C

Rationale: The correct answer is C: Seminal vesicles. These glands are located posterior to the bladder and anterior to the rectum. They secrete an alkaline fluid rich in fructose, which nourishes and supports sperm viability. The other choices are incorrect because: A) The prostate is located below the bladder and surrounds the urethra, secreting a milky fluid; B) The bulbourethral gland is located below the prostate and secretes a clear, viscous fluid; D) The spongy urethra is a part of the male urethra that runs through the penis, responsible for transporting urine and semen.

Correct Answer: C

Rationale: The correct answer is C: Proliferative phase. During this phase, the endometrium thickens in preparation for a potential implantation of a fertilized egg. This phase occurs after the menstrual phase and before ovulation, marking the time when the ovarian follicles are developing under the influence of FSH. The other choices are incorrect because the menstrual phase (A) refers to the shedding of the endometrium, the preovulatory phase (B) occurs just before ovulation, and the follicular phase (D) includes both the menstrual and preovulatory phases.

Correct Answer: A

Rationale: The correct answer is A: dihydrotestosterone (DHT). DHT is a potent form of testosterone responsible for male sexual development, including the formation of the urethra, prostate, and external genitals. It binds to androgen receptors in target tissues, promoting their growth and differentiation. FSH (Choice B) is follicle-stimulating hormone, which primarily regulates sperm production in males. Progesterone (Choice C) is a female sex hormone involved in the menstrual cycle and pregnancy. Estrogen (Choice D) is a female sex hormone responsible for female reproductive development. Thus, A is the correct answer as it specifically pertains to male sexual differentiation.