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SingaporeCombined ScienceQuick questions
Biology: Cells and Human Physiology
Quick questions on Transport in humans and the circulatory system explained: O-Level Combined Science
5short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is a double circulation?Show answer
Humans have a double circulation: blood passes through the heart twice for each complete circuit. One loop carries blood from the heart to the lungs and back (to pick up oxygen); the other carries blood from the heart to the rest of the body and back. This keeps oxygenated and deoxygenated blood separate and delivers oxygen at high pressure.
What is the heart?Show answer
The heart is a muscular pump with four chambers: two upper atria and two lower ventricles. The right side pumps deoxygenated blood to the lungs; the left side pumps oxygenated blood to the body. The left ventricle has a thicker, more muscular wall because it must pump blood at high pressure all around the body. Valves between the chambers and in the vessels stop blood flowing backwards.
What is q1?Show answer
State the function of red blood cells and the substance they use to do it. [2 marks]
What is q2?Show answer
Explain why the wall of the left ventricle is thicker than the wall of the right ventricle. [2 marks]
What is q3?Show answer
Name the type of blood vessel that allows exchange of substances with the cells and state one feature that suits this. [2 marks]
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