Page 175 - SUBSEC October 2017_Neat

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02107032/CAPE/SPEC/KMS 2017

BIOLOGY

UNIT 1 -- PAPER 032
MARK SCHEME

Question 3. UK XS

(a) Apparatus required:

 Measuring cylinders
 Beakers 2
 Test tubes
 Test tube holders / test tube racks
 Syringes / pipettes
 Bunsen burner or water bath

4 points -- 2 marks
3 points -- 1 mark

(b) Reagents required:

 Benedict’s solution
 Distilled water 1
 Glucose

2 points -- 1 mark

(c) To make 0.75M glucose solution

 Place 25 cm of distilled water in a measuring cylinder.
 Use a syringe (or pipette) to draw up 75 cm of the 1M
glucose solution. Add to the 25 cm of water in the 1
measuring cylinder.
 Place mixture in a labelled beaker.

 To make the other dilutions repeat the procedure above
using the ratios given below:

0.5M → 50 cm 1M glucose solution: 50 cm distilled 1
water.

0.25M → 25 cm 1M glucose solution: 75 cm distilled 1
water.

 Place 2 ml (1 -- 5 ml) of glucose in test tube.
 Add equal amount of Benedict’s reagent. 1
 Heat, record colour.