The primary sex organ in the male is the _____.

Correct Answer: B

Rationale: The correct answer is B: testis. The testis is the primary male sex organ responsible for producing sperm and testosterone. It is located within the scrotum. The penis (choice A) is the male reproductive organ used for sexual intercourse but is not the primary sex organ. The scrotum (choice C) is the external sac that houses the testes but is not the primary sex organ itself. The epididymis (choice D) is a coiled tube located on the testis where sperm mature and are stored, but it is not the primary sex organ.

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: C

Rationale: The correct answer is C: vulva. The vulva includes the labia, clitoris, and vestibular glands. The labia are the outer folds of skin, the clitoris is a highly sensitive erectile structure, and the vestibular glands are located around the vaginal opening. The vulva encompasses all these structures, making it the most inclusive term among the options provided. The other choices are incorrect because they are specific structures that are part of the vulva but do not encompass all the other terms listed.

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.