Surname
Centre
No.
Initial(s)
Paper Reference
Signature
Candidate
No.
Paper Reference(s)
4325/03
4437/07
London Examinations IGCSE
Examiner’s use only
Team Leader’s use only
Biology – 4325
Paper 3
Science (Double Award) – 4437
Question Leave
Number Blank
1
Paper 7
2
Foundation and Higher Tiers
3
Tuesday 17 November 2009 – Morning
Time: 1 hour 15 minutes
4
5
6
Materials required for examination
Nil
Items included with question papers
Nil
Instructions to Candidates
In the boxes above, write your centre number, candidate number, your surname, initial(s), the paper
reference and your signature.
The paper references are shown above. Write the one for which you have been entered. Check that
you have the correct question paper.
Answer ALL the questions. Write your answers in the spaces provided in this question paper.
Do not use pencil. Use blue or black ink.
Show all stages in any calculations and state the units. Calculators may be used.
Information for Candidates
The marks for individual questions and the parts of questions are shown in round brackets: e.g. (2).
There are 6 questions in this question paper. The total mark for this paper is 50.
There are 16 pages in this question paper. Any blank pages are indicated.
Advice to Candidates
Write your answers neatly and in good English.
Total
This publication may be reproduced only in accordance with
Edexcel Limited copyright policy.
©2009 Edexcel Limited.
Printer’s Log. No.
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Answer ALL the questions. Write your answers in the spaces provided.
1.
Food tests can be carried out on a sample of food to see if it contains certain substances.
(a) Use the correct words from the list to complete the table to show the solutions used,
the colour of the solutions at the start and the colour of the solutions at the end.
Benedict’s
Substance
tested for
Biuret
blue
Solution
used
iodine
pink
Colour of
solution at start
black
red
white
Colour of
solution at end
yellow
Heat
required
starch
no
glucose
yes
(3)
(b) In the test for glucose the solution needs to be heated.
Give two precautions you would use to heat the solution safely.
1 ....................................................................................................................................
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2 ....................................................................................................................................
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(2)
Q1
(Total 5 marks)
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2.
Plants absorb gas through their leaf surfaces.
The photographs show the lower surfaces of the leaves of two plant species.
The images are of the same high magnification.
epidermis cells
Leaf A
Leaf B
pores
(a) (i) Name the pores labelled on the photographs.
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(1)
(ii) Describe how these pores change when the plant leaf is exposed to bright light in
the morning.
Explain how this change benefits the plant.
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(3)
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(b) Look at the photographs and complete the table.
Feature
Leaf A
Leaf B
number of pores
shape of epidermis cells
(3)
(c) The diagram shows apparatus that can be used to measure water loss from a leafy
shoot.
½
°
°
¾
°
°¿
leafy shoot
capillary
tube
air bubble
water
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(i) Describe how the apparatus is used to measure the rate of water loss.
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(3)
(ii) State one precaution you should take to make sure that the apparatus works
correctly.
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(1)
(iii) The rate of water loss from a leafy shoot changes with a higher wind speed.
Describe how you could show this using this apparatus.
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(2)
(Total 13 marks)
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Q2
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3.
Ian set up an experiment to measure the carbon dioxide gas released when bean seeds start
to germinate.
He wanted to compare the rate of gas production at two different temperatures, 10 °C and
20 °C.
thermometer
cotton wool
boiling tube
test tube
bean seeds
indicator
(a) To make sure that the gas released is carbon dioxide, Ian uses an indicator.
What indicator should Ian use, and what changes would he see, as the gas is
released?
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(2)
(b) Name two variables that need to be kept constant at each temperature.
1 ....................................................................................................................................
2 ....................................................................................................................................
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(c) Ian counted the number of bubbles of gas released in a minute at 10 °C and at 20 °C.
He wrote his results as follows.
10°C
1st minute 11 bubbles
2nd minute 9 bubbles
3rd minute 7 bubbles
4th minute 8 bubbles
20°C
1st minute 16 bubbles
2nd minute 15 bubbles
3rd minute 13 bubbles
4th minute 11 bubbles
In the space below draw a suitable table and use it to show Ian’s results.
(3)
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(d) Describe and explain Ian’s results.
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(2)
(e) Ian measured the rate of gas production by counting the bubbles released in a minute.
Suggest a more accurate way of measuring the rate of gas production.
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(2)
(f) (i) Ian’s teacher explained that the gas in the boiling tube expands as the temperature
increases. Explain how this could have affected Ian’s results.
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(2)
(ii) Suggest how Ian could modify his experiment to take account of this effect.
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(1)
Q3
(Total 14 marks)
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4.
Describe an investigation you could do to find out the effect of carbon dioxide concentration
on the movement of insect larvae.
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(Total 6 marks)
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Q4
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5.
The graph shows how the concentration of starch changes as it is digested by an
enzyme.
starch
concentration
0
5
10
time in minutes
(a) Describe how the concentration of starch changes with time.
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(2)
(b) Starch is being digested less quickly at ten minutes than at two minutes.
Suggest an explanation for this.
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(1)
(c) State one variable that should have been kept constant during this experiment.
For this variable describe how you could keep it constant.
Variable .........................................................................................................................
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How variable kept constant ..........................................................................................
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(2)
Q5
(Total 5 marks)
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6.
Bethany wanted to investigate where plants of two different species tend to grow.
She wanted to see if plant species A and plant species B grew equally on the slope of a hill
and on level ground in the same field.
She used a 0.5 m u 0.5 m quadrat to sample the number of the two different plant species
found on the slope of a hill and on level ground.
She sampled each area three times and recorded her results in the following tables.
Slope of hill
Quadrat
Tally of
plant A
Number of
plant A
Tally of
plant B
Number of
plant B
1
1111
4
1111 111
8
2
11
2
1111 1111 11
12
3
1111
4
1111 11
Level ground
Quadrat
Tally of
plant A
Number of
plant A
Tally of
plant B
Number of
plant B
1
1111 1111 111
13
1111
4
2
1111 1111
1111
14
1111
5
3
1111 1111
9
1111 1
6
(a) Complete the table to show the number of plant B in quadrat 3 on the slope of the
hill.
(1)
(b) (i) Complete the table below by calculating the mean number of plant B per quadrat
growing on the slope of the hill.
Area
Mean number of plant A
Slope of hill
3.33
Level ground
12.00
Mean number of plant B
5.00
(1)
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(ii) On the grid below, plot a bar chart to show the mean number of plants per quadrat
growing in each area.
(3)
(c) Describe how the distribution of plants A and B varies in each area.
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(2)
Q6
(Total 7 marks)
TOTAL FOR PAPER: 50 MARKS
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