MCAT Biology Question 98: Answer and Explanation

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Question: 98

8. Which of the following is true regarding arteries and veins?

  • A. Arteries are thin-walled, muscular, and elastic, whereas veins are thick-walled and inelastic.
  • B. Arteries always conduct oxygenated blood, whereas veins always carry deoxygenated blood.
  • C. The blood pressure in the aorta is always higher than the pressure in the superior vena cava.
  • D. Arteries facilitate blood transport by using skeletal muscle contractions, whereas veins make use of the pumping of the heart to push blood.

Correct Answer: C

Explanation:

The only answer choice that correctly describes arteries and veins is choice (C); the pressure in the aorta is usually about 120 or 80 mmHg, depending on whether the heart is in systole or diastole, whereas the pressure in the superior vena cava is near zero. Choice (A) is incorrect because arteries are thick-walled and veins are thin-walled. Choice (B) is also incorrect; this relationship is reversed in pulmonary and umbilical circulation. Choice (D) is reversed as well; arteries make use of the pumping of the heart and the "snapping back" of their elastic walls to transport blood, whereas venous blood is "pumped" by skeletal muscle contractions.

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