A newborn infant obtains maternal antibodies from the mother's

Correct Answer: B

Rationale: The correct answer is B: colostrum. Colostrum is the first milk produced by the mother after giving birth. It is rich in antibodies, providing passive immunity to the newborn. This helps protect the infant from infections until its own immune system fully develops. A: laguno - Not a substance related to maternal antibodies. C: rubell - Incorrect spelling and not relevant to maternal antibodies. D: placent - While the placenta does provide nutrients and oxygen to the fetus, it is not the source of maternal antibodies transferred to the newborn.

Correct Answer: A

Rationale: The correct answer is A because the respiratory bud does indeed start to appear at the ventral wall of the foregut around week 10 of gestation. This marks the beginning of respiratory system development. Choice B is incorrect as there are actually 5 stages of respiratory system development. Choice C is also incorrect as the development of the respiratory tract is not fully complete until after birth, not just in the last week of fetal development. Choice D is incorrect because the epithelial respiratory lining is derived from endoderm, not endodermal.

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: secretion of alkaline mucus. The prostate gland produces alkaline mucus that helps neutralize the acidic environment of the vagina, thus enhancing sperm viability. Spermatogenesis (choice A) occurs in the testes, not the prostate. The production of glycogen (choice B) is not a function of the prostate. While the prostate does play a role in sperm transport and nourishment, it does not directly impact the maturation of sperm cells (choice D).

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.