Patella is a

Correct Answer: C

Rationale: The patella is a sesamoid bone located within the tendon of the quadriceps femoris muscle. Sesamoid bones are small, round bones embedded within tendons, providing protection and improving the mechanical advantage of the muscle. It is not irregular (A), short (B), or flat (D) as it does not fit the structural characteristics of those bone types. Therefore, the correct answer is C.

Correct Answer: C

Rationale: The correct answer is C: scrotum. The scrotum is a pouch of skin that houses the testes, which are responsible for producing sperm and testosterone. It is considered an external male reproductive organ because it plays a crucial role in maintaining the optimal temperature for sperm production. The penis is also an external male reproductive organ, but it is not part of the scrotum. The urethra is a passage for both urine and semen, and while it is part of the male reproductive system, it is not considered an external reproductive organ. The prostate and seminal vesicle are internal male reproductive organs involved in producing and secreting seminal fluid, making them incorrect choices in this context.

Correct Answer: D

Rationale: The correct answer is D: Liquid. Sound vibrations travel through the inner ear mainly through the liquid-filled cochlea. When sound waves reach the ear, they cause the fluid inside the cochlea to move, stimulating hair cells that convert the vibrations into electrical signals sent to the brain. Choice A (Bone) is incorrect as bone conduction bypasses the middle ear, while sound must pass through it to reach the cochlea. Choice B (Nerve fibers) is incorrect because nerves transmit the electrical signals generated by the hair cells, not sound vibrations themselves. Choice C (Air) is incorrect as the inner ear is filled with liquid, not air, and sound waves need a medium like air to travel through the ear canal but not inside the inner ear.

Correct Answer: D

Rationale: The correct answer is D. Ethnicity is a risk factor for prostate cancer. African American men have a higher risk compared to other ethnicities. This is supported by research and epidemiological studies. Choice A is incorrect as prostate cancer, when detected early, has a high survival rate. Choice B is also incorrect as prostate cancer is one of the most common cancers in men. Choice C is incorrect as having a family history of prostate cancer is a known risk factor.

Correct Answer: C

Rationale: The correct answer is C: An inhibitor of progesterone’s actions. Progesterone is responsible for maintaining the uterine lining, and inhibiting its actions would prevent menstruation. Testosterone (A) and FSH (B) do not directly affect menstruation. Prostaglandin E2 (D) is involved in the menstrual process, but inhibiting it would not necessarily stop menstruation.