What is the primary function of antibodies?
- A. Production of white blood cells
- B. Initiation of gluconeogenesis
- C. Promotion of intracellular storage of lipids
- D. Facilitate the breakdown of antigens
Correct Answer: D
Rationale: The correct answer is D: Facilitate the breakdown of antigens. Antibodies are protein molecules produced by the immune system in response to the presence of foreign substances, known as antigens, in the body. Antibodies bind to specific antigens and mark them for destruction by other immune cells, thereby helping the body to defend against infections and other threats. Choices A, B, and C are incorrect because antibodies do not have a direct role in the production of white blood cells, initiation of gluconeogenesis, or promotion of intracellular storage of lipids. The primary function of antibodies is to target and facilitate the destruction of antigens in the body.
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Which of these body parts does not contain melanin?
- A. Hair
- B. Nails
- C. Skin
- D. Iris
Correct Answer: D
Rationale: The iris is the colored part of the eye that determines the eye's color. Melanin is not present in the iris, unlike hair, nails, and skin. Melanin gives color to hair, nails, and skin, but not to the iris. Therefore, the correct answer is the iris (Choice D). Choices A, B, and C contain melanin and are incorrect.
Which valve allows blood flow from the right atrium into the right ventricle?
- A. Tricuspid valve
- B. Pulmonic valve
- C. Mitral valve
- D. Aortic valve
Correct Answer: A
Rationale: The correct answer is the Tricuspid valve. This valve is located between the right atrium and the right ventricle in the heart. Its primary function is to facilitate the flow of blood from the right atrium into the right ventricle and to prevent the backflow of blood. The Pulmonic valve (choice B) is situated between the right ventricle and the pulmonary artery, not between the right atrium and ventricle, making it incorrect. The Mitral valve (choice C) is found between the left atrium and the left ventricle, not the right side, so it is incorrect. The Aortic valve (choice D) is positioned between the left ventricle and the aorta, not involved in the right atrium and ventricle connection, hence it is also incorrect.
Which of the following areas has the least amount of sweat glands?
- A. Back
- B. Palms
- C. Axilla
- D. Forehead
Correct Answer: B
Rationale: The correct answer is B - Palms. The palms have the least amount of sweat glands compared to the other options listed. The back, axilla (armpits), and forehead are all areas with a higher concentration of sweat glands in the body. The palms have fewer sweat glands to minimize water loss and maintain a better grip for activities requiring precise and controlled movement. The back, axilla, and forehead have more sweat glands to assist in thermoregulation and cooling of the body, while the palms have fewer sweat glands for functional reasons related to grip and dexterity.
What is surgically altered during a vasectomy?
- A. Vas deferens
- B. Glans penis
- C. Prostate
- D. Urethra
Correct Answer: A
Rationale: During a vasectomy, the vas deferens is surgically altered or cut to prevent the transport of sperm from the testicles to the urethra. This procedure is a form of permanent male sterilization. The glans penis, prostate, and urethra are not surgically altered during a vasectomy. Therefore, the correct answer is the vas deferens (Choice A), as it is the structure specifically targeted and modified in this procedure. The glans penis (Choice B) is the sensitive tip of the penis, the prostate (Choice C) is a gland vital for semen production but not involved in a vasectomy, and the urethra (Choice D) is the tube that carries urine and semen but is not surgically altered in a vasectomy.
What is the action of the triceps reflex?
- A. Forces contraction of the triceps and extension of the arm.
- B. Forces contraction of the biceps, relaxation of the biceps, and arm extension.
- C. Causes the triceps to contract, causing the forearm to supinate and flex.
- D. Causes the triceps to relax and the upper arm to pronate and extend.
Correct Answer: A
Rationale: The triceps reflex causes the triceps muscle to contract, leading to the extension of the arm. This reflex is a protective response to sudden stretching of the triceps muscle, as seen when a physician taps the triceps tendon during a physical examination. Choice A is the correct answer as it accurately reflects the action of the triceps reflex. Choices B, C, and D are incorrect because they describe actions that are not associated with the triceps reflex. Biceps contraction, forearm supination, flexion, triceps relaxation, and pronation are not part of the triceps reflex arc.