(d) (i) involvement of platelets / eg platelets clotting process / release ‘trigger’ enzyme(s) / release factors’ ‘clotting 1 fibrinogen to fibrin or meshwork formed (which traps blood cells) 1 (ii) any four from: to gain 4 marks candidates should include at least: one advantage and one disadvantage Advantages (improved circulation / O2 supply) provides: more cell respiration • more energy released • (more) active life / not so tired / more physical activity • Disadvantages danger of surgery / operation • infection from surgery / operation • valve may need replacing • clots may form and block blood vessels • may need to take anti-coagulants eg warfarin – clots may cause heart attacks / strokes • 4 [17] M11.(a) A - atrium ignore references to right / left 1 B - ventricle 1 (b) (i) muscular 1 (ii) push blood
(d) (i) involvement of platelets / eg platelets ‘trigger’ clotting process / release enzyme(s) / release ‘clotting factors’ 1 fibrinogen to fibrin or meshwork formed (which traps blood cells) 1 (ii) any four from: to gain 4 marks candidates should include at least: one advantage and one disadvantage Advantages (improved circulation / O2 supply) provides: • more cell respiration • more energy released • (more) active life / not so tired / more physical activity Disadvantages • danger of surgery / operation • infection from surgery / operation • valve may need replacing • clots may form and block blood vessels may need to take anti-coagulants – eg warfarin • clots may cause heart attacks / strokes 4 [17] M11.(a) A - atrium ignore references to right / left 1 B - ventricle 1 (b) (i) muscular 1 (ii) push blood
b4_organisation_in_animals_mark_scheme.docx