Where do sperm cells attain fertilization competence and motility?

Correct Answer: B

Rationale: The correct answer is B: epididymis. Sperm cells attain fertilization competence and motility in the epididymis. Here's the rationale: 1. Sperm cells are produced in the seminiferous tubules of the testes. 2. They then move to the epididymis for maturation, where they gain motility and the ability to fertilize an egg. 3. The epididymis provides the ideal environment for sperm to undergo final maturation processes. 4. The rete testis is a network of tubules where sperm are transported from the seminiferous tubules, not where they gain fertilization competence. 5. The vas deferens is a duct that carries sperm from the epididymis to the urethra, not where sperm attain fertilization competence.

Correct Answer: A

Rationale: The correct answer is A: fimbriae. Fimbriae are finger-like projections at the end of the fallopian tube that capture the released oocyte from the ovary during ovulation. The fimbriae create a gentle sweeping motion to guide the oocyte into the uterine tube for fertilization. The other choices are incorrect because the oocyte needs to be captured by the fimbriae before entering the uterine tube, infundibulum, or uterus. The fimbriae are the initial structure responsible for receiving the oocyte, making choice A the correct answer.

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: inner cell mass. After fertilization, the zygote undergoes several cell divisions to form a hollow ball of cells called a blastocyst. Within the blastocyst, the inner cell mass contains cells that will develop into the fetus. The morula is an earlier stage consisting of a solid ball of cells. The zygote is the initial cell formed from the fusion of egg and sperm, but it does not directly become the fetus. Therefore, the inner cell mass is the structure that will actually develop into the fetus, making it the correct answer.

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.