Science — AI-generated practice question

Double circulation is the process in which blood passes through the heart twice during each cycle of circulation through the body. In one cycle, deoxygenated blood goes from the heart to the lungs for oxygenation and returns to the heart; then oxygenated blood is pumped from the heart to the rest of the body. It occurs in mammals and birds.

Source: Chapter 5, Section 5.4.1 – Transportation in Human Beings

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• The key phrase examiners look for is "blood passes through the heart twice in one cycle."
• Briefly mention both loops: heart → lungs → heart (pulmonary), and heart → body → heart (systemic).
• Mentioning that it occurs in mammals/birds adds value and may fetch full marks.
• Avoid confusing this with the four-chambered heart description — focus on the circulation pattern, not the heart structure.