Science — CBSE Class 10 board question

Transport of Oxygenated Blood:
Oxygenated blood from the lungs enters the left atrium. When the left atrium contracts, blood moves to the left ventricle, which then pumps it to the rest of the body through arteries.

Transport of Deoxygenated Blood:
Deoxygenated blood from the body enters the right atrium. It then passes to the right ventricle, which pumps it to the lungs for oxygenation.

This is called double circulation — blood passes through the heart twice in one complete cycle. The separation of oxygenated and deoxygenated blood ensures a highly efficient supply of oxygen to the body.

Source: Life Processes, Section 5.4.1

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• Examiners expect you to trace both pathways clearly: lungs → left side → body, and body → right side → lungs.
• Mention the chambers (atria and ventricles) by name — this fetches marks.
• The term double circulation is a key term that must appear for full marks.
• Avoid writing long paragraphs; two short labelled sections (oxygenated/deoxygenated) make the answer neat and easy to evaluate.