Science (Double Award) – 4437 Question Leave Paper 7 ...

Paper Reference(s)

4325/03 4437/07London Examinations IGCSEBiology – 4325Paper 3Science (Double Award) – 4437Paper 7Foundation and Higher TiersThursday 11 May 2006 – AfternoonTime: 1 hour 15 minutes

Materials required for examination Items included with question papersRuler, pencil and eraser Nil

Instructions to CandidatesIn 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 in the spaces provided in this question paper.Show all the steps in any calculations and state the units.Calculators may be used.

Information for CandidatesThe total mark for this paper is 50. The marks for parts of questions are shown in round brackets: e.g. (2).There are 16 pages in this question paper. All blank pages are indicated.

Advice to CandidatesWrite your answers neatly and in good English.

Examiner’s use only

Team Leader’s use only

Question Leave Number Blank

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Paper Reference (complete below)

This publication may be reproduced only in accordance with Edexcel Limited copyright policy. ©2006 Edexcel Limited.

Printer’s Log. No.

N24617AW850/4325/57570 5/5/6/700

www.egyptigstudentroom.com

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egyptigstudentroom.comwww.egyptigstudentroom.com

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1. The diagrams show pieces of apparatus you would need to use in some biology investigations.

Complete the table to show the apparatus you would use in each investigation.

Write one letter in each box. The first one has been done for you.

Investigation

To find out the size of a plant cell

To find out the total number of flowers in a field

To find out if plants bend towards the light

To find out if water snails produce carbon dioxide

To find out if body temperature increases during exercise

Letter of apparatus

E

Q1

(Total 4 marks)

A quadrat

C bottle ofhydrogencarbonate

indicator

E microscope

B thermometer

D stopwatch

F light bulb


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2. A farmer had some wheat seeds that were 20 years old. He wanted to know if age has an effect on germination of wheat seeds. He asked some students in a local school if they could find out the answer.

The students obtained wheat seeds of different ages. They put ten seeds of each age onto wet cotton wool in dishes. The seeds were left to germinate for five days and the results are shown in the drawings.

4-year old seeds

12-year old seeds

20-year old seeds

1-year old seeds

8-year old seeds

16-year old seeds

Key

= germinated seed

= seed not germinated


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(a) (i) Use the information in the drawings to complete the table below. The first one has been done for you.

(2)

(ii) The students also produced a table showing the percentage of seeds that had germinated. This table is shown below, but is not complete.

Complete the table by calculating the percentage germination for 12-year-old seeds. Put your answer into the empty box in the table.

(1)

Age of wheat seedsin years

Number ofgerminated seeds

Number of seedsnot germinated

1 9 1

4

8

12

16

20

Age of wheat seedsin years Percentage of seeds that germinated (%)

1 90

4 90

8 80

12

16 10

20 0


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(iii) On the grid plot a line graph to show how the percentage of seeds that germinated changed with the age of the seeds.

(5)

(iv) What advice should the students give to the farmer about using his 20-year-old seeds? Explain your answer.

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................................................................................................................................(2)

(b) Give two factors that the students should keep the same to make their investigation fair.

1. ...................................................................................................................................

2. ...................................................................................................................................(2)

(c) Give one way in which the students could make their results more reliable.

.......................................................................................................................................(1) Q2

(Total 13 marks)


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3. Some students read that maggots move away from light. They thought this behaviour would help maggots move deeper into the dead bodies of animals.

To investigate this idea they placed 30 maggots in a dish with a lid. The left hand side of the lid was dark. The right hand side of the lid was clear and so let light in. The diagram below shows a section through the apparatus.

The students left the apparatus for 10 minutes. Then they counted the number of maggots in each side.

The diagrams below show a view of the apparatus from above, at the start of the investigation and after 10 minutes.

(a) (i) Give one way that the experiment was set up as a fair test.

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................................................................................................................................(1)

(ii) How many maggots were in the dark side after 10 minutes.

................................................................................................................................(1)

lid

dish

maggot

maggot

At start After 10 minutes


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(b) The experiment was carried out six times (trials). The results, after 10 minutes, are shown in the table.

TrialNumber of maggots in each side

of the apparatus

Dark side Light side

1 22 8

2 20 10

3 25 5

4 14 16

5 24 6

6 22 8

Total number 127 ?

(i) Calculate the missing value for the total number of maggots found on the light side.

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(ii) Look at the pattern of all the results. Which trial has produced an anomalous (unexpected) result?

................................................................................................................................(1)

(iii) Suggest an explanation for the anomalous result.

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(c) Describe how the students could modify the apparatus to set up a control for this investigation to be sure the results were only due to the effect of light on the maggots.

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.......................................................................................................................................(1) Q3

(Total 6 marks)


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4. A student wanted to find out how change in temperature affected the rate of carbon dioxide production by yeast during anaerobic respiration. He used the apparatus below to measure 30 cm3 of a glucose solution.

(a) (i) What is the name of the piece of apparatus?

................................................................................................................................(1)

(ii) Draw a line on the apparatus to show a volume of 30 cm3.

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(b) Yeast was added to the 30 cm3 of glucose solution. The apparatus below was then set up to measure the carbon dioxide production.

bung

oil

30 cm3 of yeast and glucose mixture

beaker of water to act as a water bath

water

rubber tube


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(i) Suggest why a layer of oil was put on the top of the yeast and glucose mixture.

................................................................................................................................(1)

(ii) Describe how this apparatus could be used to measure the rate of carbon dioxide production at any temperature.

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................................................................................................................................(2)

(c) To measure the rate of carbon dioxide production at different temperatures the apparatus was put into a water bath that could be set up at different temperatures. The results are shown on the graph.

(i) Describe how the rate of carbon dioxide production changed with temperature as shown by the graph.

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................................................................................................................................(3)

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�

��

��

��

�

�

�

�

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(ii) It is known that enzymes in yeast break down glucose and release carbon dioxide during anaerobic respiration. Use your biological knowledge to explain the results shown on the graph.

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................................................................................................................................(3)

(d) Suggest how the students could extend and improve this investigation to obtain a more accurate idea of the temperature that produces the most carbon dioxide gas.

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.......................................................................................................................................(2) Q4

(Total 13 marks)


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5. A student used a potometer to study loss of water from a leafy shoot. She compared the loss of water in still air and in windy conditions.

The diagram shows how the apparatus was set up.

She measured the distance in mm moved by the bubble in five minutes. She took four readings in still air and four readings in windy conditions. Her rough notes of the results are shown below.

rubber tube

leafy shoot

water

air bubble

capillary tube


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(a) (i) In the space below draw a table with suitable headings and put her results into your table.

(4)

(ii) Describe how she calculated her average (mean) result for still air.

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

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................................................................................................................................(2)

(b) She concluded: “All plants lose more water as the wind increases”.

Suggest three ways in which further work would help her obtain more evidence that is valid to support this conclusion.

1. ...................................................................................................................................

2. ...................................................................................................................................

3. ...................................................................................................................................(3)

TURN OVER FOR QUESTION 6

Q5

(Total 9 marks)


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6. Describe an investigation you could carry out to find out what effect drinking tea has on heart rate.

Include full experimental details in your account.

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TOTAL FOR PAPER: 50 MARKS

END

Q6

(Total 5 marks)


Science (Double Award) – 4437 Question Leave Paper 7 ...

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