Nokea
The development strategy where the young develop within their mother's uterus and obtain nourishment from the mother via placenta is best described as
- A. Oviparity.
- B. Viviparity.
- C. Semelparity.
- D. Ovoviviparity.
Correct Answer: B
Rationale: The correct answer is B: Viviparity. Viviparity refers to the development strategy where young develop within the mother's uterus and receive nourishment through the placenta. This is the best description for the scenario provided.
A: Oviparity involves laying eggs externally.
C: Semelparity is a reproductive strategy where an organism reproduces only once in its lifetime.
D: Ovoviviparity is a combination of oviparity and viviparity, where eggs are retained within the mother's body until they hatch.
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_______ 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.
The main structures in erectile tissue responsible for maintaining an erection are the:
- A. pacinian corpuscles
- B. peripheral nerves
- C. helicine arteries
- D. Acrosome phase
Correct Answer: C
Rationale: The correct answer is C: helicine arteries. Helicine arteries are the main structures in erectile tissue responsible for maintaining an erection. They dilate in response to signals from the nervous system, allowing increased blood flow into the penis, leading to an erection. Pacinian corpuscles (A) are sensory receptors for touch and pressure, not involved in erectile function. Peripheral nerves (B) transmit signals between the brain and the penis but are not directly responsible for maintaining an erection. Acrosome phase (D) is a term related to sperm structure and not relevant to erectile tissue function.
The outer fibrous vascular membrane that covers the surface of a long bone is termed as
- A. Endomysium
- B. Periosteum
- C. Perimysium
- D. Endosteum
Correct Answer: B
Rationale: The correct answer is B: Periosteum. The periosteum is the outer fibrous vascular membrane that covers the surface of a long bone. It plays a crucial role in bone growth, repair, and nutrition. The endomysium (A) is a connective tissue sheath that surrounds individual muscle fibers, not bones. The perimysium (C) is a connective tissue sheath that surrounds bundles of muscle fibers, not bones. The endosteum (D) is a thin membrane that lines the inner surface of bones, not the outer surface. Therefore, the periosteum is the correct choice for the outer fibrous vascular membrane covering a long bone.
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
The process of release of ovum from the ovary is termed as
- A. Dessication
- B. Ovulation
- C. Fenestration
- D. Maturation
Correct Answer: B
Rationale: The correct answer is B: Ovulation. Ovulation is the process of the release of the mature egg (ovum) from the ovary. During ovulation, the egg is released into the fallopian tube where it can potentially be fertilized by sperm. Dessication (A) refers to the process of drying out, Fenestration (C) is the creation of an opening or hole, and Maturation (D) is the process of becoming mature. Therefore, the correct term specifically related to the release of the egg from the ovary is ovulation.