Biology 0610/63 October/November 2025: question paper and mark scheme
Cambridge IGCSE Biology (0610), Paper 6 Alternative to Practical, October/November 2025. Read both free below, or download them. Done the paper? Get it marked by AI against this mark scheme.
Yeast cells produce an enzyme called invertase. Invertase catalyses the breakdown of sucrose into reducing sugars. Sucrose is not a reducing sugar.
A student investigated the effect of two different concentrations of invertase extract on a sucrose solution.
The student used this method:
Step 1 Label three test-tubes A, B and W.
Step 2 Use a syringe to put 2 cm3 of sucrose solution into all three test-tubes.
Step 3 Use a clean syringe to put 2 cm3 of 100% invertase extract into test-tube A.
Step 4 Use a clean syringe to put 2 cm3 of 10% invertase extract into test-tube B.
Step 5 Use a clean syringe to put 2 cm3 of distilled water into test-tube W.
Step 6 Put all three test-tubes in a warm water-bath at 40 °C for 15 minutes.
Step 7 Measure the temperature of the liquid in the test-tubes.
(a) State the name of the piece of equipment that is used to measure temperature.
…… [1]
Step 8 Use a clean syringe to add 4 cm3 of Benedict’s solution to all three test-tubes.
Step 9 Place all three test-tubes into a hot water-bath for five minutes.
Step 10 After five minutes, record the colour of the liquid in each test-tube.
Fig. 1.1 shows the notes the student made about their observations in step 10.
the liquid in test-tube A is brick-red
the liquid in test-tube B is green
W remains blue
Fig. 1.1
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3
(b) Prepare a table and record the results of this investigation using the information in Fig. 1.1.
[3]
(c) State a conclusion for the results shown in test-tube A and test-tube B.
…… [1]
(d) Explain the purpose of test-tube W.
…… [2]
(e) State the independent variable in this investigation.
…… [1]
(f) Explain why the test-tubes were placed in the warm water-bath in step 6.
…… [1]
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4
(g) Explain why a clean syringe was used in steps 3, 4 and 5.
…… [1]
(h) Invertase is a protein.
State the reagent used to test for the presence of protein.
…… [1]
[Total: 11]
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5
Mark scheme
1(a) thermometer ; 1
1(b) table drawn with a minimum of two columns and a header 3 e.g.
line ;
appropriate column / row headings ; test-tube colour (of liquid)
three colours recorded correctly for tubes A, B and W ; A brick-red
B green
W blue
1(c) the greater the (invertase/enzyme) concentration the greater 1
the concentration of , reducing sugars / glucose, produced ;
ora
1(d) as a control ; 2
idea that, water does not break down sucrose / sucrose
does not break down on its own ;
1(e) concentration of invertase/enzyme (extract) ; 1
1(f) any one from: 1
to make sure test-tubes are at the same temperature ;
to give a sufficient / high rate of reaction / AW ;
so that the test-tubes are at the same temperature as the
water-bath ;
1(g) to prevent contamination / AW ; 1
1(h) biuret ; 1
A student investigated the effect of temperature on the rate of respiration in yeast cells.
They used the apparatus shown in Fig. 2.1.
clamp
measuring yeast cylinder
suspension
water water-bath
Fig. 2.1
The student used this method:
• Put 25 cm3 of yeast suspension into a test-tube.
• Put the test-tube into a water-bath and add water at 10 °C to the water-bath.
• Leave the apparatus for five minutes before moving on to the next step.
• Start a stop-clock and count the number of bubbles produced by the respiring yeast cells in three minutes.
• Repeat the procedure using a water-bath maintained at different temperatures.
(a) (i) State two variables that the student kept constant in this investigation.
1 ……
2 ……
[2]
(ii) State one possible source of error when measuring the dependent variable and suggest an improvement to this method of measuring.
error ……
improvement ……
[2]
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(b) Table 2.1 shows the results of the investigation.
Table 2.1
water-bath temperature number of bubbles produced in rate of bubble production
/ °C 3 minutes / bubbles per minute
10 33 11
20 45 15
30 79
40 112 37
50 124 41
60 37 12
(i) Calculate the rate of bubble production at 30 °C.
Give your answer to an appropriate number of significant figures.
Space for working.
…… bubbles per minute [2]
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7
(ii) Plot the data in Table 2.1 on the grid to show the effect of temperature on the rate of bubble production.
[4]
(iii) Describe the results of this investigation.
…… [2]
(c) Describe how the student could confirm that the gas produced is carbon dioxide.
…… [2]
[Total: 14]
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8
Mark scheme
2(a)(i) any two from: 2
volume of yeast ;
time for equilibration / AW ;
same time for, counting bubbles / respiration ;
same type of yeast ;
2(a)(ii) error: 2
bubbles may be different sizes / too fast to count / AW ;
improvement:
measure the volume ;
2(b)(i) 26 ;; 2 MP1 correct division by 3 = 26.33333
MP2 correct rounding to two significant figures to match
table values
2(b)(ii) axes labelled ; 4 (water) temperature / °C and rate (of bubble production) /
bubbles per minute
suitable linear scale and plotted area occupies at least half
the grid in both directions ;
plots accurate to ± half small square ;
smooth line / curve of best fit or points joined with straight
lines ;
2(b)(iii) as temperature increases, the number of bubbles / rate of 2
bubble production, increases and then decreases ;
reference to, peak / AW, at 50°C ;
2(c) use limewater ; 2
turns cloudy / milky / forms a white precipitate ;
OR
hydrogencarbonate indicator ;
turns yellow ;
(a) Fig. 3.1 is a photograph of the head of a king penguin.
A B
magnification ×0.42
Fig. 3.1
(i) Make a large drawing of the head of the king penguin shown in Fig. 3.1.
[4]
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(ii) The length of line AB represents the length of the penguin’s beak.
Measure the length of line AB in Fig. 3.1.
length of line AB …… mm
Use your measurement and the formula to calculate the actual length of the penguin’s beak.
length of line AB in Fig. 3.1 magnification = actual length of the penguin’s beak
Give your answer to one decimal place.
Space for working.
…… mm
[3]
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10
(b) Fig. 3.2 shows the heads of a gentoo penguin and a black-footed penguin.
gentoo black-footed
not to scale
Fig. 3.2
Other than size, state two ways the gentoo penguin differs from the black-footed penguin in
Fig. 3.2.
1 ……
2 ……
[2]
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11
(c) Penguins are covered in feathers. The feathers reduce heat loss by insulating the birds from the cold.
A beaker of hot water can be used to represent a penguin.
Plan an investigation to determine the effect of the thickness of an insulating material on heat loss in a beaker of hot water.
…… [6]
[Total: 15]
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12
Mark scheme
3(a)(i) outline clear and continuous, no shading ; 4
size greater than half of space provided ;
detail 1: tear-shaped white patch on the left with a border
and tear-shaped white patch below the beak ;
detail 2: two or more lines on the beak ;
3(a)(ii) 46±1 (mm) ; 3 MP1 correct measurement of line AB
109.5 (mm) ;; MP2 correct calculation to any number of decimal places
i.e. 46 ÷ 0.42 = 109.5238
MP3 correct rounding to one decimal place
ecf from previous MP
3(b) any two from: 2
Gentoo has:
less white area / white patch around eye is triangular-
shaped vs semicircular-shaped ;
rounder / bigger / wider eye ;
slimmer / narrower / thinner / sharper, beak ;
larger pale area on beak / no stripe vs black-footed has a
stripe ;
smoother beak ;
3(c) 1 independent variable 6
at least two different thicknesses of insulation (used as an
insulator) ;
2 dependent variable
change in temperature / time taken for a stated fall in
temperature ;
3 and 4 method ;;
• method of insulating beaker with named material
• measure the starting temperature and final temperature
5, 6 and 7 variables kept constant ;;;
• volume of water
• size
• type of beaker
• time left to cool / stated fall in temperature
• starting temperature
• type of insulator
• same surroundings / environmental temperature
8 repeat investigation twice more / at least two replicates ;
9 relevant safety precaution ;
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On this page, free: the mark scheme for IGCSE Biology 0610/63, October/November 2025 (0610_w25_ms_63), and the question paper (0610_w25_qp_63), to read or download, with each question's marking points written out underneath.
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Biology 0610/63 for October/November 2025 is out of 40 marks, with 1 hour to answer it, across 3 questions.
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