Cambridge IGCSE™

* 9 2 9 2 8 7 7 4 6 6 *

COMBINED SCIENCE 0653/61

Paper 6 Alternative to Practical October/November 2023

1 hour

You must answer on the question paper.

No additional materials are needed.

INSTRUCTIONS
● Answer all questions.
● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
● Write your name, centre number and candidate number in the boxes at the top of the page.
● Write your answer to each question in the space provided.
● Do not use an erasable pen or correction fluid.
● Do not write on any bar codes.
● You may use a calculator.
● You should show all your working and use appropriate units.

INFORMATION
● The total mark for this paper is 40.
● The number of marks for each question or part question is shown in brackets [ ].

This document has 16 pages. Any blank pages are indicated.

DC (CJ/FC) 319390/3
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1 A student investigates the effect of an enzyme used in the large-scale production of apple juice
from apples.

(a) Procedure

The student:

step 1 labels two test-tubes E and W

step 2 uses a spatula to add apple puree (crushed apple) to each test-tube

step 3 adds 10 cm3 of the enzyme to the test-tube labelled E

step 4 adds 10 cm3 of distilled water to the test-tube labelled W

step 5 stirs the contents of each test-tube using a clean glass rod

step 6 puts both test-tubes in a beaker containing 250 cm3 of water at an initial temperature
of 40 °C

step 7 waits for 10 minutes and then measures the final temperature of the water in the
beaker.

(i) Fig. 1.1 shows the reading on the thermometer.

50 °C

40

30

Fig. 1.1

Record the final temperature of the water.

final temperature of water = .................................................... °C [1]

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(ii) The student:

step 8 filters the contents of each test-tube as shown in Fig. 1.2

filter paper filter paper

containing containing
contents of contents of
test-tube E test-tube W

apple juice

Fig. 1.2

step 9 collects the juice in a measuring cylinder for 5 minutes.

Fig. 1.3 shows the volume of juice collected in each measuring cylinder after 5 minutes.

50 30
cm3 cm3

40 20

30 10

E W

Fig. 1.3

Record in Table 1.1 the volume of apple juice collected from each test-tube to the nearest
0.5 cm3.

Table 1.1

volume of apple juice collected

test-tube
/ cm3
E
W
[2]

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(iii) Use the results to suggest why this enzyme is used in the large-scale production of
apple juice.

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

..................................................................................................................................... [1]

(iv) Use your answer in (a)(i) to decide if temperature is a source of error in this investigation.

Tick (✓) the appropriate box and explain your decision.

temperature is a source of error

temperature is not a source of error

explanation ........................................................................................................................

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

...........................................................................................................................................
[1]

(v) Identify one source of error in step 2.

Suggest a suitable piece of apparatus to overcome this error.

error ...................................................................................................................................

apparatus ..........................................................................................................................
[1]

(vi) Suggest why it is important to use a clean glass rod in step 5.

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

..................................................................................................................................... [1]

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(b) Fig. 1.4 shows a section through an apple.

Fig. 1.4

In the box, make a large clear pencil drawing of the apple section shown in Fig. 1.4.

[3]

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(c) Fig. 1.5 shows some cells in apple puree.

A B

Fig. 1.5

(i) Line AB represents the width of the apple cell labelled X.

Measure the length of line AB.

length of line AB = .................................................. mm [1]

(ii) The cells in Fig. 1.5 are magnified ×160.

Calculate the actual width of the apple cell labelled X.

Use the equation shown.

length of line AB
actual width of cell X =
magnification

Give your answer to two significant figures.

actual width of cell X = .................................................. mm [2]

[Total: 13]

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2 (a) When magnesium ribbon is added to dilute hydrochloric acid, the mixture fizzes and makes
hydrogen gas. The magnesium ribbon stays on the surface of the acid during the reaction.
The reaction is complete when all the magnesium ribbon disappears and the fizzing stops.

State the test used to confirm the presence of hydrogen gas and give the observation for a
positive result.

test ............................................................................................................................................

observation ...............................................................................................................................
[1]

(b) A student investigates the rate of reaction between magnesium ribbon and dilute
hydrochloric acid.

Procedure

The student:

step 1 adds 25 cm3 of dilute hydrochloric acid to a glass beaker

step 2 puts a 5 mm length of magnesium ribbon into the dilute hydrochloric acid and
immediately starts a stop-watch

step 3 uses a glass rod to keep the magnesium ribbon under the surface of the
dilute hydrochloric acid but not touching the bottom of the beaker

step 4 stops the stop-watch when all the magnesium ribbon has reacted

step 5 records in Table 2.1 the reaction time (the time it takes for all the magnesium ribbon
to react) to the nearest second

step 6 repeats step 1 to step 5 four more times using 10 mm, 15 mm, 20 mm and 25 mm
lengths of magnesium ribbon instead of 5 mm.

(i) In step 1, the student uses a measuring cylinder to measure 25 cm3 of dilute
hydrochloric acid.

Suggest one other piece of apparatus suitable for measuring 25 cm3 accurately.

..................................................................................................................................... [1]

(ii) Explain the importance of step 3 in the procedure.

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

..................................................................................................................................... [1]

(iii) Suggest one source of uncertainty in the measurement of the reaction time.

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

..................................................................................................................................... [1]

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(iv) Fig. 2.1 shows the stop-watch readings for 5 mm and 25 mm lengths of magnesium
ribbon.

0:30.09 0:30.69

5 mm length 25 mm length

Fig. 2.1

Record in Table 2.1 the reaction times in Fig. 2.1 to the nearest second.

Table 2.1

length of magnesium ribbon reaction time rate of reaction in

/ mm /s mm / s
5
10 31 0.32
15 29 0.52
20 30 0.67
25
[2]

(v) Calculate the rate of reaction for the 5 mm and 25 mm lengths of magnesium ribbon.

Use the equation shown.

length of magnesium ribbon

rate of reaction = reaction time

Record your values in Table 2.1. [1]

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(vi) On the grid, plot a graph of the rate of reaction (vertical axis) against the length of
magnesium ribbon.

[3]

(vii) Draw the line of best fit. [1]

(viii) Describe the relationship between the rate of reaction and the length of magnesium
ribbon.

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

..................................................................................................................................... [1]

(c) The student repeats the procedure in (b) using a 100 mm length of magnesium ribbon.

The student concludes that the magnesium ribbon is in excess.

Suggest an observation the student makes to reach this conclusion.

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

............................................................................................................................................. [1]

[Total: 13]

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3 A student investigates the reflection of light by a plane mirror.

(a) Fig. 3.1 on page 11 shows a horizontal line XZ.

Line NY is the normal to line XZ at point Y.

Line AY meets line XZ at point Y.

The angle of incidence i is the angle between line AY and the normal, as shown in Fig. 3.1.

Measure the angle of incidence i in Fig. 3.1.

i = ....................................................... ° [1]

(b) Procedure

The student:

• puts the mirror along line XZ with the reflecting face of the mirror facing the letter N on
Fig. 3.1
• places two pins, P1 and P2, on line AY at least 5 cm apart.

(i) On Fig. 3.1, mark with crosses suitable positions for pins P1 and P2.

Label the crosses P1 and P2. [1]

(ii) Procedure

The student:

• looks into the mirror from the position of the eye shown in Fig. 3.1
• views the images of pins P1 and P2 in the mirror
• places two pins, P3 and P4, to the right of the normal, so that pins P3 and P4 and the
images of pins P1 and P2 all appear lined up, one behind the other.

The position of pin P3 is already shown on Fig. 3.1.

Mark with a cross a suitable position for pin P4.

Label the cross P4. [1]

(c) Draw a straight line through the positions of pins P3 and P4.

Continue the Iine until it meets line XZ.

Label the angle θ between line P3P4 and line XZ.

Measure angle θ.

θ = ....................................................... ° [2]

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position of mirror
Y
X Z
i
P3

A
eye

Fig. 3.1

(d) Procedure

The student:

• repeats the experiment for i = 30°, 45° and 60°

• takes three readings of θ for each value of i
• records the results in Table 3.1.

Table 3.1

θ /°
i /°
reading 1 reading 2 reading 3
30 61 59 29
45 46 47 45
60 31 28 30

The student notices that there is an anomalous reading in Table 3.1.

(i) Circle the anomalous reading. [1]

(ii) Suggest what the student does to improve the data.

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

..................................................................................................................................... [1]

[Total: 7]

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4 Plan an investigation to determine the relationship between the temperature of apple juice and the
time it takes for ice cubes to melt when added to it.

You are provided with:

• ice cubes of different shapes and sizes

• a supply of apple juice
• beakers.

You may use any other common laboratory apparatus.

In your plan, include:

• any other apparatus you will need

• a brief description of the method, including what you will measure and how you will make
sure your measurements are accurate
• the variables you will control
• a results table to record your measurements (you are not required to enter any readings in
the table)
• how you will process your results to draw a conclusion.

You may include a labelled diagram if you wish.

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.................................................................................................................................................... [7]

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at www.cambridgeinternational.org after the live examination series.

Cambridge Assessment International Education is part of Cambridge Assessment. Cambridge Assessment is the brand name of the University of Cambridge
Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge.

© UCLES 2023 0653/61/O/N/23