O-LevelBiologyTransport in Humans5090/22 · Oct/Nov 2014 · Q910 Marks
Explain what is meant by the term double circulation.
- (a)Explain what is meant by the term double circulation.[4]
- (b)Explain how the heart is adapted to keep blood flowing in a double circulation.[6]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2014). The mark or mark type is shown in brackets.
- [max. 4] blood goes through heart twice (in one complete circuit of the body);
- circulation to/from lungs / pulmonary ;
- circulation to/from (rest of) body / systemic ;
- lungs + low pressure ;
- body + high pressure ;
- [max. 6] two sides to the heart / heart completely divided ;
- four chambers / two atria + two ventricles / all 4 named chambers ;
- beats continually ;
- right side / atrium + receives blood from body ;
- right side / ventricles + pumps blood to lungs ;
- left side / atrium receives blood from lungs ;
- left side / ventricle + pumps blood to (rest of) body ;
- left ventricle thicker-walled / more muscular + than right ventricle ;
- ventricles thicker-walled / more muscular + than atria;
- further to pump blood / generate higher pressure ;
- ref. valves + one-way flow / prevent backflow ;
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