Name the components of human blood and explain how each component carries out its function.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2015). The mark or mark type is shown in brackets.

1. [max 10] 1 red blood cells + transport/absorb/carry oxygen AW;
2. [max 10] 2 no nucleus/biconcave/'doughnut' shape AW + increased surface area;
3. [max 10] 3 (oxy)haemoglobin ;
4. [max 10] 4 ref. (oxygen) diffusion into tissues/red blood cells ;
5. [max 10] 5 white blood cells/named + immunity/immune system/destroy pathogens/bacteria/viruses/named pathogen;
6. [max 10] 6 phagocytes/phagocytosis;
7. [max 10] 7 antibodies/anti-toxins;
8. [max 10] 8 ref. tissue rejection ;
9. [max 10] 9 plasma + transport/carry;
10. [max 10] 10 dissolved/in solution;
11. [max 10] 11 two named chemicals transported;
12. [max 10] 12 heat transported;
13. [max 10] 13 platelets + blood clotting/plug hole;
14. [max 10] 14 fibrinogen + to fibrin ;