MCAT Biology Practice Test 7: The Cardiovascular System

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1. Which of the following is a FALSE statement regarding erythrocytes?

  • A. Erythrocytes contain hemoglobin.
  • B. Erythrocytes are anaerobic.
  • C. The nuclei of erythrocytes are located in the middle of the biconcave disc.
  • D. Erythrocytes are phagocytized in the spleen and liver after a certain period of time.

2. Which of the following is the correct sequence of a cardiac impulse?

  • A. SA node → AV node → Purkinje fibers → bundle of His → ventricles
  • B. AV node → bundle of His → Purkinje fibers → ventricles → atria
  • C. SA node → atria → AV node → bundle of His → Purkinje fibers → ventricles
  • D. SA node → AV node → atria → bundle of His → Purkinje fibers → ventricles

3. Hemoglobin's affinity for O2:

  • A. increases in exercising muscle tissue.
  • B. decreases as blood PaCO2 decreases.
  • C. decreases as blood pH decreases.
  • D. is higher in maternal blood than in fetal blood.

4. Which of the following correctly traces the circulatory pathway?

  • A. Superior vena cava → right atrium → right ventricle → pulmonary artery → lungs → pulmonary veins → left atrium → left ventricle → aorta
  • B. Superior vena cava → left atrium → left ventricle → pulmonary artery → lungs → pulmonary veins → right atrium → right ventricle → aorta
  • C. Aorta → right atrium → right ventricle → pulmonary artery → lungs → pulmonary veins → left atrium → left ventricle → superior vena cava
  • D. Superior vena cava → right atrium → right ventricle → pulmonary veins → lungs → pulmonary artery → left atrium → left ventricle → aorta

5. At the venous end of a capillary bed, the osmotic pressure:

  • A. is greater than the hydrostatic pressure.
  • B. results in a net outflow of fluid.
  • C. is significantly higher than the osmotic pressure at the arterial end.
  • D. causes proteins to enter the interstitium.

6. A patient's chart reveals that he has a cardiac output of 7500 mL per minute and a stroke volume of 50 mL. What is his pulse, in beats per minute?

  • A. 50
  • B. 100
  • C. 150
  • D. 400

7. An unconscious patient is rushed into the emergency room and needs an immediate blood transfusion. Because there is no time to check her medical history or determine her blood type, which type of blood should she receive?

  • A. A–
  • B. AB+
  • C. O+
  • D. O–

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.

9. At any given time, there is more blood in the venous system than the arterial system. Which of the following features of veins allows for this?

  • A. Relative lack of smooth muscle in the wall
  • B. Presence of valves
  • C. Proximity of veins to lymphatic vessels
  • D. Thin endothelial lining

10. Which of the following is involved in the body's primary blood-buffering mechanism?

  • A. Fluid intake
  • B. Absorption of nutrients in the gastrointestinal system
  • C. Carbon dioxide produced from metabolism
  • D. Hormones released by the kidney

11. Due to kidney disease, a person is losing albumin into the urine. What effect is this likely to have within the capillaries?

  • A. Increased blood pressure
  • B. Increased hydrostatic pressure
  • C. Decreased oncotic pressure
  • D. Decreased hydrostatic pressure

12. The tricuspid valve prevents backflow of blood from the:

  • A. left ventricle into the left atrium.
  • B. aorta into the left ventricle.
  • C. pulmonary artery into the right ventricle.
  • D. right ventricle into the right atrium.

13. The world record for the longest-held breath is 22 minutes and 0 seconds. If a sample were taken from this individual during the last minute of breath-holding, which of the following might be observed?

  • A. Increased hemoglobin affinity for oxygen
  • B. Decreased PaCO2
  • C. Increased hematocrit
  • D. Decreased pH

14. A person has a heart attack that primarily affects the wall between the two ventricles. Which portion of the electrical conduction system is most likely affected?

  • A. AV node
  • B. SA node
  • C. Bundle of His
  • D. Left ventricular muscle

15. Which vascular structure creates the most resistance to blood flow?

  • A. Aorta
  • B. Arterioles
  • C. Capillaries
  • D. Veins