Nokea
Testosterone is converted to _____ in the prostate.
- A. cholesterol
- B. estrogen
- C. progesterone
- D. dihydrotestosterone
Correct Answer: D
Rationale: The correct answer is D: dihydrotestosterone. Testosterone is converted to dihydrotestosterone (DHT) in the prostate by the enzyme 5-alpha reductase. DHT is a more potent androgen that plays a crucial role in prostate growth and development. Choice A (cholesterol) is incorrect as it is not a product of testosterone conversion in the prostate. Choice B (estrogen) is incorrect as testosterone is not directly converted to estrogen in the prostate. Choice C (progesterone) is incorrect as progesterone is not the main product of testosterone conversion in the prostate.
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During the latter stages of pregnancy, many women experience an increase in body hair growth in a masculine pattern. What is the explanation for this?
- A. The ovaries secrete some testosterone along with the large amounts of estrogen produced late in pregnancy
- B. The fetal ovaries and testes secrete androgenic steroids
- C. The maternal and fetal adrenal glands secrete large amounts of androgenic steroids that are used by the placenta to form estrogen
- D. The placenta secretes large amounts of estrogen, some of which is metabolized to testosterone
Correct Answer: C
Rationale: Step 1: Maternal and fetal adrenal glands secrete androgenic steroids.
Step 2: Placenta uses these androgenic steroids to form estrogen.
Step 3: Increased estrogen levels can lead to body hair growth.
Therefore, the correct answer (C) is supported by the process of androgenic steroids being secreted by the adrenal glands, utilized by the placenta to form estrogen, resulting in increased body hair growth.
Summary:
A (The ovaries secrete some testosterone along with estrogen) is incorrect as testosterone is not primarily secreted by the ovaries late in pregnancy.
B (The fetal ovaries and testes secrete androgenic steroids) is incorrect as the primary source of androgenic steroids in this context is the adrenal glands, not fetal ovaries or testes.
D (The placenta secretes estrogen, some of which is metabolized to testosterone) is incorrect as the main source of estrogen in this scenario is from the and
__________ is an example of an oviparous animal.
- A. Pigeon
- B. Elephant
- C. Sheep
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: Pigeon. Oviparous animals lay eggs to reproduce, like birds. Pigeons belong to the avian class, known for laying eggs. Elephants and sheep are viviparous mammals, giving birth to live young. "None of the above" is incorrect as pigeons are indeed oviparous.
Between puberty and menopause, monthly, the following occurs :
- A. the maturation of a single secondary ovarian follicle;
- B. the transformation of a primordial follicle into a secondary one;
- C. the release of an oocyte;
- D. the release of a de Graaf follicle;
Correct Answer: C
Rationale: The correct answer is C: the release of an oocyte. During the menstrual cycle, ovulation occurs where a mature egg (oocyte) is released from the ovary. This typically happens around the middle of the cycle in response to hormonal changes. This process is essential for fertilization and pregnancy to occur.
A, B, and D are incorrect because:
A: the maturation of a single secondary ovarian follicle - This occurs before ovulation, not during the menstrual cycle.
B: the transformation of a primordial follicle into a secondary one - This is an earlier stage in follicle development, not a monthly occurrence.
D: the release of a de Graaf follicle - The Graafian follicle is the mature follicle that releases the oocyte during ovulation, not a monthly event.
Which of the following components of the fetoplacental (endocrine) unit is similar to thyroid stimulating hormone (TSH) and stimulates T4 secretion by the maternal thyroid?
- A. Human chorionic gonadotropin (hCG)
- B. Human chorionic somatomammotropin (hCS, hPL)
- C. IGF I and IGF II
- D. Endothelial growth factor (EGF)
Correct Answer: A
Rationale: Rationale:
1. Human chorionic gonadotropin (hCG) acts like TSH, stimulating T4 secretion by the maternal thyroid.
2. hCG is produced by the placenta and has a similar structure and function to TSH.
3. hCG binds to the TSH receptor on the thyroid gland, triggering T4 release.
4. Other options do not specifically target the thyroid gland for T4 secretion.
Summary:
A: hCG mimics TSH and directly stimulates T4 release.
B: hCS, hPL - involved in placental growth and lactation, not thyroid stimulation.
C: IGF I and II - growth factors, not directly related to thyroid function.
D: EGF - promotes cell growth and differentiation, not linked to thyroid hormone secretion.
Where does the epididymis direct sperm cells into?
- A. vas efferens
- B. vas deferens
- C. rete testis
- D. prostate gland
Correct Answer: B
Rationale: The epididymis directs sperm cells into the vas deferens. Sperm mature in the epididymis and are stored there until ejaculation. The vas deferens then carries the mature sperm from the epididymis to the urethra for ejaculation. The other choices are incorrect because the vas efferens carries sperm from the rete testis to the epididymis, the rete testis is a network of tubules where sperm is collected from the seminiferous tubules, and the prostate gland secretes fluids that contribute to semen but does not direct sperm flow.