Edexcel IGCSE Biology 2.14B enzyme rate calculations
Practise enzyme-rate calculations by using percentage change, mean rate, controlled variables and standardised colour endpoints.
- Syllabus
- First assessment 2019
- Course
- Biology 4BI1
Exam points
- Calculate percentage change or mean rate from enzyme investigation tables.
- Select controlled variables such as temperature, potato mass, buffer volume and exposure time.
- Improve accuracy by standardising colour endpoints with a colour chart or reference sample.
2.14B Effect of pH on enzyme activity practical question 1
[Maximum number: 6]
Some scientists have investigated the effect of vinegar (a weak acid) on the digestion of starch.
Design an investigation to discover the effect of vinegar on the digestion of starch.
Include experimental details in your answer and write in full sentences.
C use different concentrations of vinegar / vinegar and no vinegar / range of pH acids / eq
O of same mass of starch / flour / bread /potato / rice / eq
R repeat (for each concentration (of vinegar) / eq
M1 use iodine to test for (digestion of) starch
M2 measure time it takes for all starch to be digested / iodine test to be negative / orange / yellow / or description of negative positive result / eq
S1 same temperature / use water bath / eq
S2 same time to react / same volume of amylase / same concentration of amylase / same mass of amylase / same volume of vinegar / same volume of iodine / same volume Benedic'ts /eq
allow amount / more or less for C
ignore amount
Benedict's
if starch still present will be blue black
allow same volume of vinegar if vary conc in C
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