Standard Science Primary 5 Systems

Blood flowing from the lungs to the heart is rich in __________.

A Nitrogen
B Oxygen
C Water Vapor
D Carbon Dioxide
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Worked Solution

Step 1: In the lungs, gaseous exchange occurs. Step 2: Blood picks up oxygen and drops off carbon dioxide. Step 3: The pulmonary vein carries oxygenated blood back to the heart.

Correct answer: Oxygen

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