Page 483 - SUBSEC October 2017_Neat

02212032/CAPE/SPEC/MS/2017
- 5 –

CHEMISTRY
UNIT 2 — PAPER 032
MARK SCHEME
KC UK XS
Question 3

S.O.: Module: 1 ----3.3

(i) Hypothesis: For example, chromatograms will be 1
identical/different from beef and chicken. [1 mark]

(ii) Aim [1 mark]
1

(iii) Apparatus and materials
(Subtract one mark if fume hood missing) [2 marks]
2

(iv) Procedure

 Hydrolyse with dilute acid
 At least 30 mins
 Use of visualising agent
 Use of appropriate solvent
 Separate using chromatography 2

 Compare 2 chromatograms [2 marks]

(v) Variables to control: amount of each protein, time of
2
hydrolysis, Vol. acid. [2 marks]

(vi) Variables to be manipulated: proteins [1 mark] 1

(vii) Responding variable [1 mark] 1

(viii) Discussion of results as it relates to Hypothesis:
compare Rf values of different components of the 2
proteins. [1 mark] 1

(x) Possible sources error:

For example: proteins could be incompletely hydrolysed

– introduction of extraneous protein from improper

handling. [2 marks]
2

(xi) Precautions

For example: use of fume hood; be careful not to touch

chromatography paper with fingers; introduce protein to
2
sample, etc. [2 marks]

5 10

Total 15 marks