Answer either question 8 or question 9. (a) Describe the double circulation of blood in the human circulatory system and the different functions of the two circuits. (b) Describe the structure of a capillary and the transfer of a named material between capillaries and tissue fluid.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2016). The mark or mark type is shown in brackets.

1. [1] through heart twice (during one circuit) AW ;
2. [1] circuit + to lungs/pulmonary;
3. [1] blood to become oxygenated/pick up oxygen ;
4. [1] blood to lose carbon dioxide;
5. [1] circuit + to body tissues/systemic ;
6. [1] to deliver oxygen/glucose (to body tissues) ;
7. [1] collect carbon dioxide;
8. [1] reference to part of heart+named vessel ;
9. [1] low pressure lungs/high pressure body;
10. [1] one cell thick/thin/1µm + wall ;
11. [1] small diameter of lumen/RBC single file/width of RBC AW;
12. [1] no muscle/no elastic tissue (compared with artery/vein);
13. [1] leaky walls AW ;
14. [1] diffusion;
15. [1] reference to named material;