Nokea
Testosterone produces negative feedback to:
- A. the anterior pituitary to turn off follicle stimulating hormone secretion
- B. the anterior pituitary to turn off both luteinizing hormone and follicle stimulating hormone secretion
- C. Sertoli cells turn off inhibin secretion
- D. the anterior pituitary to turn off luteinizing hormone secretion
Correct Answer: D
Rationale: Step-by-step rationale:
1. Testosterone inhibits the release of luteinizing hormone (LH) through negative feedback.
2. LH is produced by the anterior pituitary.
3. Therefore, testosterone exerts negative feedback on the anterior pituitary to turn off LH secretion.
4. This maintains hormonal balance in the body.
Summary of other choices:
A. Incorrect because testosterone primarily affects LH secretion, not follicle stimulating hormone (FSH).
B. Incorrect as it inaccurately suggests that testosterone turns off both LH and FSH secretion.
C. Incorrect because Sertoli cells are involved in spermatogenesis, not LH regulation.
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Testosterone is secreted by
- A. Leydig cells.
- B. Sertoli cells.
- C. spermatocytes.
- D. early spermatids.
Correct Answer: A
Rationale: Testosterone is secreted by Leydig cells in the testes. Leydig cells are interstitial cells located between the seminiferous tubules. They are responsible for producing and secreting testosterone, which plays a crucial role in stimulating the development of male secondary sexual characteristics and maintaining male reproductive functions. Sertoli cells provide nourishment and support for developing sperm cells but do not secrete testosterone. Spermatocytes and early spermatids are involved in the process of spermatogenesis and do not secrete testosterone. Therefore, the correct answer is A because Leydig cells are specifically known for their role in testosterone production.
Chemotherapeutic agents affect cancer cells by
- A. destroying all affected tumor tissue
- B. preventing antigen-antibody response
- C. interfering with manufacture of cellular nucleic acids
- D. encouraging normal cells to overtake cancer cells
Correct Answer: C
Rationale: Chemotherapy works by interfering with the ability of cancer cells to divide and grow.
Which of the following has no homolog in the female?
- A. penis
- B. scrotum
- C. prostate
- D. bulbourethral glands
Correct Answer: B
Rationale: The correct answer is B: scrotum. The scrotum is a male-specific structure that houses the testes, which are responsible for producing sperm. In females, there is no homologous structure that serves the same function as the scrotum. The other choices (A: penis, C: prostate, D: bulbourethral glands) have homologous structures in females (clitoris, Skene's glands, and Bartholin's glands, respectively). This differentiation is based on the embryological development of male and female reproductive structures.
As menstruation ends estrogen levels in the blood rise rapidly. What is the source of the estrogen?
- A. Corpus luteum
- B. Developing follicles
- C. Endometrium
- D. Stromal cells of the ovaries
Correct Answer: B
Rationale: The correct answer is B: Developing follicles. After menstruation, the developing follicles in the ovaries produce estrogen. This estrogen is responsible for thickening the endometrium in preparation for potential implantation of a fertilized egg. The corpus luteum produces progesterone, not estrogen. The endometrium is the inner lining of the uterus and is not a direct source of estrogen. Stromal cells of the ovaries are supportive cells and do not produce estrogen.
When a male is castrated before puberty, he becomes:
- A. Female
- B. Cretin
- C. Eunuch
- D. Potent
Correct Answer: C
Rationale: The correct answer is C: Eunuch. When a male is castrated before puberty, he becomes a eunuch because castration removes the testes, leading to a lack of testosterone production and loss of male secondary sexual characteristics. This results in a eunuch having a more neutral appearance and lacking the ability to reproduce.
A: Choosing "Female" is incorrect because castration does not change the individual's genetic sex.
B: Selecting "Cretin" is incorrect as cretinism is a condition caused by severe thyroid hormone deficiency, not related to castration.
D: Opting for "Potent" is incorrect as castration leads to the loss of reproductive ability, making the individual infertile.