Nokea
Which cell has been fertilized by a sperm cell?
- A. primary oocyte
- B. secondary oocyte
- C. ovum
- D. oogonia
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.
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What excess cellular component do spermatids shed to become sperm during spermiogenesis?
- A. DNA
- B. Cytoplasm
- C. Flagellum
- D. Mitochondria
Correct Answer: B
Rationale: During spermiogenesis, spermatids shed excess cytoplasm to become mature sperm. This process helps streamline the sperm structure for efficient motility and fertilization. DNA (choice A) is essential for sperm function and remains within the sperm. The flagellum (choice C) is actually a necessary structure for sperm motility. Mitochondria (choice D) play a crucial role in providing energy for sperm movement. Shedding excess cytoplasm ensures that the mature sperm is streamlined and optimized for its specific functions.
At what point in life does a female begin her monthly ovarian cycle?
- A. At birth
- B. At puberty
- C. At middle age
- D. At menopause
Correct Answer: B
Rationale: The correct answer is B: At puberty. The monthly ovarian cycle, also known as the menstrual cycle, begins at puberty when a female's body matures and starts ovulating. This is typically around the age of 11-14. At birth (A), females already have all their eggs but do not start ovulating until puberty. Middle age (C) refers to the period around 40-65, which is not when the cycle begins. Menopause (D) is the cessation of the menstrual cycle, marking the end of reproductive years, typically around the age of 45-55.
_______ is a lytic enzyme released by the sperm.
- A. Hyaluronidase
- B. Trypsin
- C. Helicase
- D. None of the above
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.
Regarding gross anatomy of male reproductive system
- A. Dartos muscle is responsible to raise and lower the testes
- B. Ductus deferens penetrate the prostate gland to connect with prostatic urethra
- C. Anterior lobe of prostate gland is the main glandular tissue
- D. Buck's fascia encloses body of penis
Correct Answer: B
Rationale: The correct answer is B because the ductus deferens penetrates the prostate gland to connect with the prostatic urethra, forming the ejaculatory duct. This allows for the transport of sperm from the epididymis to the urethra during ejaculation.
A: Dartos muscle is responsible for wrinkling the scrotal skin but not raising and lowering the testes.
C: The anterior lobe of the prostate gland mainly consists of fibromuscular tissue, not glandular tissue.
D: Buck's fascia surrounds the corpora cavernosa and the corpus spongiosum of the penis, not the body of the penis itself.
Seven days after ovulation, pituitary secretion of luteinizing hormone (LH) decreases rapidly. What is the cause of this decrease in secretion?
- A. The anterior pituitary gland becomes unresponsive to the stimulatory effect of gonadotropin-releasing hormone (GnRH)
- B. Estrogen from the developing follicles exerts a feedback inhibition on the hypothalamus
- C. The rise in body temperature inhibits hypothalamic release of GnRH
- D. Secretion of estrogen and progesterone by the corpus luteum suppresses hypothalamic secretion of GnRH and pituitary secretion of LH
Correct Answer: D
Rationale: Step 1: After ovulation, the follicle transforms into the corpus luteum.
Step 2: The corpus luteum secretes estrogen and progesterone.
Step 3: Estrogen and progesterone exert negative feedback on the hypothalamus.
Step 4: This inhibits the secretion of GnRH from the hypothalamus.
Step 5: Decreased GnRH leads to reduced LH secretion from the pituitary.
Therefore, the correct answer is D because the secretion of estrogen and progesterone by the corpus luteum suppresses the hypothalamic secretion of GnRH, resulting in decreased pituitary LH secretion.
Summary:
A: Incorrect. The anterior pituitary gland's responsiveness to GnRH is not the cause of the decrease in LH secretion.
B: Incorrect. Estrogen exerts negative feedback on the hypothalamus, not the pituitary.
C: Incorrect. Rise in body temperature does not directly inhibit GnRH secretion