Biology 9700/32 — May/June 2015

Cambridge AS Level · Advanced Practical Skills · worked solutions for every part, with the mark scheme

questions

marks

120

minutes

Topics Presentation of Data and Observations · Manipulation, Measurement and Observation · Analysis, Conclusions and Evaluation · Use of the Light Microscope

Q1Manipulation, Measurement and ObservationPresentation of Data and ObservationsAnalysis, Conclusions and EvaluationFree sample

Athletes who run long distances need to drink while they are running. Their drinks often contain carbohydrates to provide energy.

You are provided with four drinks: D1, D2, D3 and D4.
Each drink contains one or more carbohydrates.

You are required to identify the carbohydrates in the drinks using the reagents provided.

(a)

(i)

Describe how you will use the reagent(s) to determine whether any of the drinks contain a polysaccharide.

(ii)

Carry out the test you have described in (a)(i) on D1, D2, D3 and D4.

Complete the table by using a tick (✓) to show the presence of a polysaccharide and a cross (✗) to show the absence of a polysaccharide, in any of D1, D2, D3 and D4.

drink	presence (✓) or absence (✗) of polysaccharide
D1
D2
D3
D4

(iii)

You are required to compare the quantity of reducing and non-reducing sugars in each of the drinks.

You will need to record the time taken for the first appearance of any colour change.
If no colour change occurs after 180 seconds (3 minutes), stop the experiment and record ‘more than 180’.

Describe how you will use the reagent(s) to test for reducing and non-reducing sugars.

reducing sugar test: ______

non-reducing sugar test: ______

(iv)

When carrying out a practical procedure, the hazards of the use of all the apparatus and all of the reagents need to be considered, then the level of risk needs to be assessed as low or medium or high.

State the hazard with the greatest level of risk when testing for reducing and non-reducing sugar.
State the level of risk of the procedure: low or medium or high.

hazard ______

level of risk ______

(v)

Carry out the tests on D1, D2, D3 and D4, as described in (a)(iii), and record your results in (a)(v).

Prepare the space below and record your results.

(vi)

The sugars in the drinks are sucrose and glucose.

Suggest which drink, D1, D2, D3 or D4, would provide the athletes with the greatest quantity of glucose, and explain why you selected this drink.

(vii)

A student wanted to investigate the concentration of reducing sugar in another drink, D5, used by athletes. Describe how the student could estimate the concentration of reducing sugar in drink D5.

(b)

The London Olympic Games of 2012 included races run over distances ranging from $100\ \text{m}$ to $42\ 200\ \text{m}$ (the Marathon).

Table 1.1 shows the average speed of the winner of five of these races over different distances. Using $\log_{10}$ of the distance makes the numbers easier to plot on a graph.

Table 1.1

$\log_{10}$ distance / m	average speed / $\text{m s}^{-1}$
2.0	10.4
2.6	9.1
3.2	7.0
4.0	6.1
4.6	5.5

You are required to use a sharp pencil for graphs.

(i)

Plot a graph of the data in Table 1.1.

Fig. 1.1

(ii)

Estimate the average speed for a race of distance $\log_{10}\ 3.5\ \text{m}$ .

...........................................................

(iii)

Describe the trend shown by the data.

(iv)

The winner of the Marathon race had trained at high altitude. Explain why this may have resulted in an increased average speed.

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Q2Use of the Light Microscope · Presentation of Data and Observations18M

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