Describe how peristalsis causes food to be moved along the alimentary canal.

Mark scheme

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

1. [6] muscles;
2. circular;
3. contract;
4. behind food;
5. longitudinal;
6. relax behind food/contract in front of food;
7. R if mention of contraction of longitudinal muscles behind food
8. pushing/forcing/squeezing (bolus/AW);
9. wave action/rhythmic ;
10. R if mention of parts outside of alimentary canal, e.g. trachea
11. Ig moving
12. [4] its muscles work on their own;
13. muscle not arranged in pairs/ORA ;
14. A ref. to one muscle
15. no flexor/ORA ;
16. no extensor/ORA ;
17. no muscle relaxes when it contracts/ORA ;
18. not attached to bones/ORA ;
19. does not cause movement at a joint/ORA ;