11. What is the primary role of the circulatory system?
A. Nutrient digestion
B. Oxygen absorption
C. Transportation of substances
D. Waste elimination
Answer: C
12. Which blood vessels have thin walls and valves?
A. Arteries
B. Veins
C. Capillaries
D. Venules
Answer: B
13. In which chamber of the heart does oxygenated blood enter?
A. Right atrium
B. Right ventricle
C. Left atrium
D. Left ventricle
Answer: C
14. What is the main component of blood responsible for oxygen transport?
A. Red blood cells
B. White blood cells
C. Platelets
D. Plasma
Answer: A
15. What is the pH of human blood?
A. 6.0
B. 7.0
C. 7.4
D. 8.0
Answer: C
16. What is the function of the windpipe (trachea) in the respiratory system?
A. Oxygen absorption
B. Air filtration
C. Nutrient digestion
D. Carbon dioxide elimination
Answer: D
17. Which organ is responsible for blood filtration and detoxification?
A. Liver
B. Kidneys
C. Lungs
D. Spleen
Answer: A
18. What is the term for the continuous process of blood circulation?
A. Blood pumping
B. Hematopoiesis
C. Blood circulation
D. Cardiac cycle
Answer: C
19. What is the name of the muscular partition between the thoracic and abdominal cavities?
A. Diaphragm
B. Peritoneum
C. Pleura
D. Alveoli
Answer: A
20. What is the normal blood pressure range for a healthy individual?
A. 90/60 mm Hg
B. 120/80 mm Hg
C. 150/100 mm Hg
D. 180/120 mm Hg
Answer: B
