Infants of mothers who had adequate nutrition during pregnancy do not require iron supplements or a diet rich in iron until about 3 months of age. Why is this?

Correct Answer: B

Rationale: The correct answer is B: The fetal liver stores enough iron to meet the infant’s needs until the third month. During pregnancy, the fetus accumulates iron stores in the liver from the mother, which can sustain the infant's iron needs for the first few months of life. This stored iron is gradually utilized by the infant as the maternal iron supply diminishes post-birth. Explanation of why the other choices are incorrect: A: Growth of the infant does require iron even in the early months for various metabolic processes and functions. C: Synthesis of new red blood cells starts shortly after birth, not necessarily after 3 months. D: Myoglobin is not directly related to iron supplementation needs in infants and is unrelated to the timing of iron supplementation requirements.

Correct Answer: A

Rationale: The correct answer is A: Sperm. Sperm is the mature male reproductive cell capable of fertilizing an egg. It carries genetic material and is designed for the process of fertilization. Spermatid (B) is an immature sperm cell not yet capable of fertilizing an egg. Primary spermatocyte (C) is a cell undergoing meiosis to produce spermatids. Spermatogonium (D) is a stem cell that gives rise to spermatocytes but is not directly involved in fertilization. Therefore, only sperm (A) is suitable for fertilizing an egg.

Correct Answer: D

Rationale: The correct answer is D: Bulbourethral glands. These glands produce thick, clear mucus that cleanses the penile urethra of acidic urine before ejaculation. This mucus helps neutralize the acidity of urine, creating a more hospitable environment for sperm to travel through. The other choices are incorrect because: A: Testes produce sperm, not mucus. B: Seminal vesicles produce a fluid rich in fructose to nourish sperm. C: Prostate produces a milky fluid that aids in sperm motility.

Correct Answer: A

Rationale: The correct answer is A: vesicular (Graafian) follicle. At the time of ovulation, the secondary oocyte is surrounded by this structure, which is a mature follicle containing a fluid-filled antrum. This structure is essential for the release of the oocyte during ovulation. The other choices, B: primary follicle, C: primordial follicle, and D: uterine (fallopian) follicle, are incorrect because primary follicles are immature, primordial follicles are the earliest stage of follicle development, and uterine (fallopian) follicle is not a correct anatomical term.

Correct Answer: A

Rationale: The correct answer is A, seminal gland, which provides a temporary storage site for immature sperm. Seminal glands are responsible for producing seminal fluid which nourishes and protects the sperm. The immature sperm are stored in the seminal gland until they mature. The other choices, B tunica albuginea, is a tough layer surrounding the testes, not involved in sperm storage. C ductus deferens is a tube that transports mature sperm from the epididymis to the urethra, not for storage of immature sperm. D is a duplicate of C, so it is incorrect.