Explain how dip sticks function to test for glucose in a sample of urine.

Mark scheme

Marking points from the official mark scheme (May/June 2017). The mark or mark type is shown in brackets.

1. max 8 of:
2. 1 stick has, pad containing / immobilised, enzymes ;
3. 2 glucose oxidase ;
4. 3 peroxidase;
5. 4 stick dipped in urine; A person, urinates / AW, on stick
6. 5 glucose reacts to give hydrogen peroxide;
7. 6 (hydrogen peroxide reacts with) colourless substance / chromogen; R dye / pigment
8. 7 to give, colour change / coloured substance ; A change to any named colour
9. 8 compare with colour chart;
10. 9 more glucose gives darker colour ;
11. 10 specific/only detects glucose ;
12. 11 AVP; e.g. does not give current blood glucose concentration not numerical
13. max 7 of:
14. high blood glucose concentration
15. 1 detected by ẞ cells ; I alpha cells I receptors
16. 2 in, islets of Langerhans / pancreas ;
17. 3 (more) insulin secreted; I produced
18. 4 into blood ;
19. 5 increases glucose absorption in liver (by phosphorylating glucose);
20. 6 increases permeability to glucose in, muscle / fat, cells or adds GLUT 4 proteins to cell surface membranes of, muscle / fat, cells;
21. 7 increases (rate of) respiration of glucose ;
22. 8 conversion of glucose to glycogen / glycogenesis ;
23. 9 inhibits secretion of glucagon / decreases gluconeogenesis ;
24. 10 negative feedback ;