Answer
Catalase is an enzyme that catalyses the breakdown of hydrogen peroxide (H2O2).
(i) Explain why H2O2 is found in living cells.
2 of:
[Living cells] metabolise / produce metabolic byproducts / substances / Living cells respire; AVP; H2O2 is a metabolic byproduct / byproduct of respiration [ 2 ]
(ii) A student carried out an investigation to see if different cell types contained different quantities of catalase. She found that cells of the liver, muscle, root and plant shoots contained the highest quantity of catalase compared to other cell types. Suggest an explanation for the student's findings.
4 of:
[All these cells require have] high energy demand / high metabolic rate; root & shoots growth areas [of plant]; liver for homeostatic/homeostasis role or, named example of activity e.g. deamination / glucose regualtion / removal of blood toxins; muscle for work; will produce high levels of H2O2 ; require high levels of catalase. [ 4 ]
(iii) Describe in detail a method the student might have used for this investigation. 1 mark is available for the quality of the writing.
7 of:
Chop / liquidise / mash liver, muscle etc; same mass of; add same volume H2O2 [each sample]; same temperature; same sized test-tube / boiling tube; measure height of bubbles / froth evolved / measure volume froth evolved; record results in suitable table; repeat; find mean value / volume / height; compare results; produce graph to compare; grammar, spelling, ordered sequence use if biological terms - award 1 mark.
[ 8 ]
[ Total: 14 ]
Category
