Biology 0610/31 October/November 2025: question paper and mark scheme
Cambridge IGCSE Biology (0610), Paper 3 Theory (Core), October/November 2025. Read both free below, or download them. Done the paper? Get it marked by AI against this mark scheme.
(a) Complete the statements about classification.
Organisms are classified into groups by the …… that they share.
The internationally agreed system for naming species is the ……
system.
The scientific name of an organism is made up of the …… name
and the …… name.
[4]
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4
(b) Fig. 1.1 shows six species of crustacean.
pincer A B
C D
E F
NOT TO SCALE
Fig. 1.1
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5
Use the key to identify each species shown in Fig. 1.1.
Write the letter of each species (A to F) in the correct box in the key.
Key
(a) pincers visible go to 2
1
(b) pincers not visible go to 4
(a) pincers are the same size go to 3
2
(b) pincers are different sizes Minuca pugnax
(a) body is nearly round Maja brachydactyla
3
(b) body is long Astacus leptodactylus
(a) body has visible segments go to 5
4
(b) body has no visible segments Daphnia pulex
(a) fewer than eight spots are visible on the body Porcellio expansus
5
(b) more than eight spots are visible on the body Porcellio haasi
[5]
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6
(c) The boxes on the left show some images of arthropods.
The boxes on the right show some names of arthropod groups.
Draw a line from each box on the left to the box showing the correct arthropod group for the image.
Draw a total of four lines.
image arthropod group
arachnids
insects
NOT TO SCALE
[4]
[Total: 13]
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7
Mark scheme
1(a) features / AW ; 4
binomial ;
genus ; MP3 and MP4 A either order
species ;
1(b) 5 6 correct = 5 marks
Minuca pugnax E 4 or 5 correct = 4 marks
3 correct = 3 marks
Maja brachydactyla A 2 correct = 2 marks
Astacus leptodactylus D 1 correct = 1 mark
go to 5
Daphnia pulex C
Porcellio expansus B
Porcellio haasi F
;;;;;
1(c) 4 one mark for each correct line from the image box
R each additional line
;;;;
(a) All carbohydrates contain the element carbon.
State two other elements that are found in all carbohydrates.
1 ……
2 ……
[2]
(b) For each small molecule listed, state one example of a large molecule that contains the small molecule.
amino acid ……
glycerol ……
glucose. ……
[3]
(c) (i) Describe what is meant by the term balanced diet.
…… [2]
(ii) Describe the importance of vitamins and minerals in a balanced diet.
vitamins ……
minerals ……
[4]
[Total: 11]
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8
Mark scheme
2(a) hydrogen ; 2 either order
oxygen ;
2(b) (named) protein ; 3
fat / oil ;
cellulose / glycogen / starch / AVP ; e.g. sucrose
2(c)(i) any two from: 2
all / 7, food groups or nutrients / AW ;
idea of the, proper / correct, quantities / proportions / AW ;
idea of (to supply) sufficient energy ;
2(c)(ii) any four from; 4
prevents (deficiency) diseases ;
(named) vitamins – max 3 marks from:
C: for healthy gums / AVP ;
C: to avoid scurvy ;
D: for strong bones / teeth / AVP ;
D: to avoid rickets ;
(named) mineral ions – max 3 marks from:
(calcium) for strong, bones / teeth / AVP ;
(calcium) to avoid named effect of lack of calcium ;
(iron) to make haemoglobin / red blood cells ;
(iron) to prevent (some types of) anaemia ;
AVP ;
e.g. correct ref. to other (named)vitamin/mineral and
functions or deficiency
Fig. 3.1 is a diagram of an animal cell.
H
J
M
K
L
Fig. 3.1
(a) (i) State the letter in Fig. 3.1 that identifies:
the cytoplasm ……
a ribosome ……
the structure that controls the activities of the cell. ……
[3]
(ii) State the name of structure K in Fig. 3.1.
…… [1]
(b) State one structure that is present in plant cells but absent in animal cells.
…… [1]
(c) State the word equation for aerobic respiration.
…… [2]
[Total: 7]
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9
Mark scheme
3(a)(i) L; 3
J;
M;
3(a)(ii) mitochondrion ; 1 A mitochondria
3(b) cell wall / chloroplast / (large permanent) vacuole ; 1
3(c) glucose + oxygen → ; 2 A reactants in either order
carbon dioxide + water ; A products in either order
(a) (i) Describe three ways the structure of a vein differs from the structure of an artery.
1 ……
2 ……
3 ……
[3]
(ii) State one function of capillaries.
…… [1]
(iii) State the name of the blood vessel that takes blood from the body to the right atrium.
…… [1]
(b) Blockages in the coronary arteries can lead to coronary heart disease.
State three risk factors for coronary heart disease.
1 ……
2 ……
3 ……
[3]
[Total: 8]
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10
Mark scheme
4(a)(i) thin(ner) wall ; 3
wide(r) / large(r), lumen ;
(has) valves ;
4(a)(ii) any one from: 1
supply cells with (named) required substances ;
removes (named) substances / waste substances ;
AVP : e.g. uptake of nutrients (in small intestine)
4(a)(iii) vena cava ; 1 I vein
4(b) any three from: 3
diet high in saturated fat / high salt intake / obesity / AW ;
lack of / AW, exercise ;
stress ;
smoking ;
genetic predisposition ;
age ;
sex ;
AVP ;; e.g. hypertension / high alcohol intake
(a) State one role of the nervous system.
…… [1]
(b) Fig. 5.1 shows a diagram of part of the nervous system involved in a reflex action.
This reflex action was caused by a person touching a spiky cactus plant.
W X
R
S
cactus
T
V
Fig. 5.1
(i) State the letters of two structures in Fig. 5.1 that are part of the peripheral nervous system.
1 ……
2 ……
[2]
(ii) Write the correct letters from Fig. 5.1 in the gaps to complete the statements about the reflex arc.
A painful stimulus such as a cactus spine is detected by …… in
the skin.
An impulse passes along …… until it reaches the spinal cord.
The impulse is passed to …… and then passes out of the
spinal cord in …… .
The impulse causes …… to produce a response.
[5]
(iii) State the name of the junction between two neurones.
…… [1]
[Total: 9]
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Mark scheme
5(a) coordination / regulation (of body functions) ; 1
5(b)(i) any two from: 2
S;
T;
X;
5(b)(ii) S; 5
T;
W;
X;
R;
5(b)(iii) synapse ; 1
(a) Aquatic ecosystems can be polluted by excess fertiliser.
Fertiliser contains nitrate ions.
(i) State one substance that plants make, using nitrate ions.
…… [1]
(ii) Describe the effects of excess fertiliser on aquatic ecosystems.
…… [3]
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12
(b) Students investigated the populations of three species in two rivers, A and B.
River B was contaminated with untreated sewage.
The students took samples from the rivers, and counted the numbers of each species in each sample.
Table 6.1 shows the results.
Table 6.1
numbers of each species in the samples species river A river B freshwater shrimp 97 1 bloodworm 15 27 sludge worm 2 74
(i) Describe the differences in the populations of the species in river A and in river B in
Table 6.1.
…… [3]
(ii) Suggest which species in Table 6.1 is the least tolerant of pollution.
…… [1]
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13
(c) Fig. 6.1 shows the population of red king crabs in an area of ocean between 1995 and 2010.
140
120
100
population of 80
red king crabs
/ thousand
60
40
20
0
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 year
Fig. 6.1
(i) Complete the sentences to describe the data shown in Fig. 6.1.
Overall the population size increased and then decreased.
In 1998, the population size of red king crabs was …… .
The largest population size of red king crabs was in the year
…… .
The population size in 1995 was the same as the population size in the year
…… .
[3]
(ii) Using the data in Fig. 6.1, calculate the percentage increase in the red king crab population between 1995 and 1999.
Give your answer to the nearest whole number.
…… % [3]
[Total: 14]
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14
Mark scheme
6(a)(i) (for making) amino acids / protein / AVP ; 1 e.g. enzymes
6(a)(ii) any three from: 3
(named aquatic) algae / plants, grow faster ;
(aquatic) animals / organisms / aquatic life, die ;
lack of oxygen in water ;
decrease of biodiversity ;
AVP ; e.g. bacteria or decomposers use up oxygen
6(b)(i) any three from: 3
more freshwater shrimps in river A ; ora
more bloodworms in river B ; ora
more sludge worms in river B / very few sludge worms in
river A ;
more organisms in river A ; ora
more worms in river B ; ora
difference in bloodworm populations is smaller (than the
other species) ;
the highest population anywhere is shrimps in river A ;
data quote ;
6(b)(ii) (freshwater) shrimp ; 1
6(c)(i) 24 000 ; 3
2000 ;
2004 ;
6(c)(ii) 333 (%) ; 3 MP1 correct values selected from the graph
MP2 correct calculation to any number of decimal places
e.g. (40 000 / 12 000) × 100 = 333.3 recurring
MP3 correct rounding to a whole number
ecf from previous step
(a) (i) State two reasons why bacteria are useful in genetic modification and biotechnology.
1 ……
2 ……
[2]
(ii) Describe the ways in which genetic modification can improve crop plants.
…… [3]
(b) Scientists investigated two enzymes that could be used in washing powders.
The activity of each enzyme was measured at pH values between 2 and 10.
Fig. 7.1 shows the results of the investigation.
35
30
25
enzyme
20 activity
/ arbitrary
15 units
10
5
0
2 3 4 5 6 7 8 9 10 pH
Key enzyme A enzyme B
Fig. 7.1
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15
(i) The list shows six conclusions.
Tick () the conclusions that can be made from the data shown in Fig. 7.1.
At pH 10, enzyme B is more active than enzyme A.
Enzyme A and enzyme B are not active at pH 4.
Enzyme B has a greater maximum activity than enzyme A.
Enzyme A has a maximum activity of 33 arbitrary units.
Enzyme A shows activity over a pH range of 6 to 10.
The largest difference in activity between enzyme A and enzyme B is at pH 5.
[3]
(ii) Many washing powders have a pH of approximately 9.
Identify the best enzyme, A or B, to use in these washing powders.
Give one reason for your choice.
enzyme ……
reason ……
[1]
[Total: 9]
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16
Mark scheme
7(a)(i) any two from: 2
rapid reproduction rate ;
ability to make complex molecules ;
AVP ; e.g.no / low, ethical concerns
7(a)(ii) any three from: 3
to confer resistance to herbicides ;
confer resistance to, insect / pests ;
to increase, yield / product ;
to improve nutritional qualities ;
AVP ;; e.g. confer resistance to pathogens / stress tolerance
(drought or extreme temperatures) / increase shelf life
7(b)(i) 3 R each additional tick
At pH 10, enzyme B is more active than enzyme A. Π;
Enzyme A and enzyme B are not active at pH 4.
Enzyme B has a greater maximum activity than
enzyme A.
Enzyme A has a maximum activity of 33 arbitrary Π;
units.
Enzyme A shows activity over a pH range of 6 to 10.
The largest difference in activity between enzyme A Π;
and enzyme B is at pH 5.
7(b)(ii) (enzyme) B and 1
idea of only enzyme B is active at pH 9 / optimum of enzyme
B is closer to pH 9 / AW ;
(a) (i) Table 8.1 describes ways carbon is transferred in the carbon cycle.
Complete Table 8.1 to show how carbon is transferred in the carbon cycle, and the names of the processes.
Table 8.1
transfer of carbon name of the process
from animals or plants to the atmosphere
from the atmosphere to plants
fossil fuel formation from …… to fossil fuel
from plants to animals
[4]
(ii) State the name of the process that involves microorganisms transferring carbon in dead organisms to the atmosphere.
…… [1]
(b) Complete the sentences about the atmosphere.
Combustion of fossil fuels …… the concentration of
carbon dioxide in the atmosphere.
This causes an …… greenhouse effect and leads to
…… .
Another gas that has a similar effect on the atmosphere to carbon dioxide is
…… .
[4]
[Total: 9]
Mark scheme
8(a)(i) 4
transfer of carbon name of the process
from animals or plants to respiration ;
the atmosphere
from the atmosphere to photosynthesis ;
plants
from fossil fuel formation
(dead) animals / plants
/ organisms ;
to fossil fuel
from plants to animals feeding / AW ;
8(a)(ii) decomposition / respiration ; 1
8(b) increases / AW ; 4
enhanced ;
climate change / global warming ;
methane / AVP ; e.g. water vapour / nitrous oxide
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On this page, free: the mark scheme for IGCSE Biology 0610/31, October/November 2025 (0610_w25_ms_31), and the question paper (0610_w25_qp_31), to read or download, with each question's marking points written out underneath.
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Biology 0610/31 for October/November 2025 is out of 80 marks, with 1 hour 15 minutes to answer it, across 8 questions.
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