Nokea
Corpus luteum;
- A. is generated as a result of ovulation;
- B. secretes estrogens;
- C. secrets progesterone;
- D. secrets low amounts of testosterone
Correct Answer: C
Rationale: The corpus luteum is formed from the ruptured follicle after ovulation. It secretes progesterone, which is crucial for preparing the uterus for implantation and maintaining early pregnancy. Progesterone helps thicken the uterine lining and supports embryo development. Estrogens are mainly produced by the ovaries, not the corpus luteum. Testosterone is primarily produced by the adrenal glands and testes, not the corpus luteum. Therefore, choice C is correct as it accurately describes the main hormone secreted by the corpus luteum.
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The mature follicle is also called a _____.
- A. Graafian follicle
- B. granulosa cell
- C. primary follicle
- D. secondary follicle
Correct Answer: A
Rationale: The correct answer is A: Graafian follicle. The mature follicle is called a Graafian follicle because it is the final stage of follicle development before ovulation. It is characterized by a fluid-filled cavity containing the oocyte. The other choices are incorrect because a granulosa cell is a type of cell found in the follicle wall, a primary follicle is an immature follicle, and a secondary follicle is an intermediate stage between the primary and Graafian follicle.
One function of the placenta in a human is to
- A. surround the embryo and protect it from shock
- B. allow for mixing of maternal blood with fetal blood
- C. act as the heart of the fetus, pumping blood until the fetus is born
- D. permit passage of nutrients and oxygen from the mother to the fetus
Correct Answer: D
Rationale: The correct answer is D because the placenta serves as a barrier between the maternal and fetal bloodstreams, allowing for the exchange of nutrients, oxygen, and waste products. This is crucial for the fetus's growth and development. Choice A is incorrect because the placenta does not physically surround the embryo. Choice B is incorrect as maternal and fetal blood do not mix due to the placental barrier. Choice C is incorrect as the heart of the fetus pumps blood, not the placenta.
Testosterone is secreted by the following structures, EXCEPT:
- A. prostate;
- B. testicular interstitial cells;
- C. seminiferous tubules;
- D. straight tubules;
Correct Answer: A
Rationale: The correct answer is A: prostate. Testosterone is primarily secreted by the testicular interstitial cells (Leydig cells) in the testes. The seminiferous tubules are responsible for spermatogenesis, not testosterone secretion. Straight tubules are involved in transporting sperm. The prostate gland produces prostatic fluid, not testosterone. Therefore, the prostate is not a structure that secretes testosterone.
The cortical area of the ovary contains:
- A. primordial follicles;
- B. mature follicles;
- C. secondary follicles;
- D. blood vessels;
Correct Answer: A
Rationale: Step 1: The cortical area of the ovary is the outer layer where follicles develop.
Step 2: Primordial follicles are the earliest stage of follicle development, found in the cortex.
Step 3: Mature follicles are developed follicles located deeper in the ovary, not in the cortex.
Step 4: Secondary follicles are also more developed than primordial follicles, located deeper.
Step 5: Blood vessels are important for supplying nutrients but are not specific to the cortical area.
Therefore, the correct answer is A as primordial follicles are located in the cortical area, while other choices are found in different regions of the ovary.
Neonates that are kept in 100% oxygen incubators for several days become blind when they are removed from the incubator, a condition referred to as retrolental fibroplasia. What is the explanation for the loss of sight?
- A. The high concentration of oxygen stimulates the growth of fibrous tissue into the retina
- B. The high concentration of oxygen causes rupture of blood vessels in the retina, resulting in fibrous infiltration of the vitreous humor
- C. The high concentration of oxygen retards the growth of blood vessels in the retina, but when the oxygen therapy is stopped, the fall in oxygen concentration stimulates an overgrowth of blood vessels in the retina and vitreous humor, which later become densely fibrous and block the light from the pupil
- D. The high concentration of oxygen destroys the retinal neurons
Correct Answer: C
Rationale: The correct answer is C because high oxygen concentration in neonates suppresses normal blood vessel growth in the retina. When oxygen therapy is stopped, oxygen levels fall, triggering excessive blood vessel growth in the retina and vitreous humor, leading to fibrous blockage of light. Option A suggests fibrous tissue growth due to oxygen, which is incorrect. Option B inaccurately states that oxygen causes vessel rupture. Option D is incorrect as oxygen does not directly destroy retinal neurons.