Biology · Oct / Nov 2023 · Paper 62 · Question 2

independent variable:

1

(at least) two different, enzyme / lipase, concentrations ; dependent variable:

2

measuring pH after a set time OR measuring time to reach a certain pH ;

detail of method:

3

use of pH meter / pH paper / (named) indicator ; 4

measure / same, initial pH / initial colour ;

5

control and description of the control e.g. using boiled enzyme / water instead of enzyme ;

6 & 7 variables kept constant – max two from ;;

8 two or more repeats / total of three or more trials ; 9

relevant safety precaution e.g. use of goggles / gloves ;

add ethanol and (then) water ;

shake ;