Which cell has been fertilized by a sperm cell?

Correct Answer: C

Rationale: The correct answer is C (ovum) because the ovum is the mature and fertilized egg cell resulting from the fusion of a sperm cell and an egg cell during fertilization. The primary oocyte (A) is an immature egg cell that has not undergone fertilization. The secondary oocyte (B) is the egg cell released during ovulation but has not yet been fertilized. Oogonia (D) are the precursor cells that give rise to primary oocytes through the process of oogenesis. Therefore, the ovum is the only choice that accurately represents a fertilized egg cell.

Correct Answer: B

Rationale: The correct answer is B: progesterone. Progesterone inhibits LH secretion by exerting negative feedback on the hypothalamus and pituitary gland. This hormone signals that the body has enough progesterone and does not need additional LH for ovulation. FSH (choice A) stimulates LH secretion, estrogen (choice C) typically increases LH secretion during the menstrual cycle, and LH (choice D) does not inhibit its own secretion.

Correct Answer: A

Rationale: The correct answer is A: Hyaluronidase. This enzyme is released by the sperm to help penetrate the outer layer of the egg during fertilization. Hyaluronidase specifically breaks down hyaluronic acid present in the cumulus cells surrounding the egg. Trypsin is a digestive enzyme found in the pancreas, not involved in sperm function. Helicase is an enzyme involved in DNA replication and repair, not released by sperm. "None of the above" is incorrect as hyaluronidase is indeed released by the sperm.

Correct Answer: B

Rationale: The correct answer is B: Seminiferous tubules. These tubules are located within the testes and are the specific structures where sperm production occurs through a process called spermatogenesis. Sperm cells are produced within the seminiferous tubules and then mature as they move through the epididymis (choice D) and vas deferens (choice A). The albuginea (choice C) is the tough outer covering of the testes and does not play a direct role in sperm production. Therefore, the seminiferous tubules are the primary site for sperm production in the male reproductive system.

Correct Answer: C

Rationale: The correct answer is C, Uterine tubes. Fertilization occurs in the uterine tubes, also known as Fallopian tubes, where the sperm and egg meet to form a zygote. The uterine tubes provide a suitable environment for fertilization to take place. A: Ureters - Incorrect, ureters are tubes that carry urine from the kidneys to the bladder, not involved in fertilization. B: Urethra - Incorrect, the urethra is a tube that carries urine from the bladder out of the body, not involved in fertilization. D: Ovaries - Incorrect, ovaries release eggs but fertilization does not occur in the ovaries; rather, it occurs in the uterine tubes.