Explain the fact that humans breathe while plants do not.

Mark scheme

Marking points from the official mark scheme (May/June 2014). The mark or mark type is shown in brackets.

1. [3] muscles in humans/no muscles in plants ;
2. ref. intercostals/diaphragm ;
3. (N.B. intercostal ; muscles ; will score 2 marks)
4. humans need to keep (constant) supply of O2 (to blood) / remove CO2 (from blood)/ref. higher metabolic rate/rate of respiration in humans ;
5. ref. production of (some of their own) oxygen by photosynthesis ;
6. lungs/no lungs ;
7. ref. stomata/spongy mesophyll in plants/not in humans/ref. alveoli in humans/no alveoli in plants ;
8. [7] (High respiration rate)
9. humans active/move/muscle + action (or described)/ORA ;
10. requires large quantities of/more + energy/ORA ;
11. high body temperature in humans/ORA ;
12. activity of enzymes/high metabolic rate/ORA ;
13. humans complex/named organs, e.g. brain, kidneys, heart;
14. R humans are larger
15. (Constant respiration rate)
16. homeostasis ;
17. temperature constant in humans/thermoregulation ;
18. rate dependent on external temperature in plants ;
19. rate dependent on stage of life cycle, e.g. germination/growing season ;