Biology 0610/43 October/November 2025: question paper and mark scheme
Cambridge IGCSE Biology (0610), Paper 4 Theory (Extended), October/November 2025. Read both free below, or download them. Done the paper? Get it marked by AI against this mark scheme.
Scientists use classification systems to study relationships between different groups of organisms.
(a) State the two parts of a scientific name used in the binomial system.
…… [1]
(b) Scientists discover a new species. It is multicellular, and has cell walls that are not made of cellulose. This new species feeds by releasing digestive enzymes into its surroundings and then absorbing the digested nutrients.
Identify the kingdom that the new species belongs to.
…… [1]
(c) Fig. 1.1 shows photographs of two different species, X and Y.
species X
species Y
Fig. 1.1
* 0000800000003 * DFD
3
(i) Species X and Y belong to the plant kingdom.
State two structures found in cells from species X and Y that are not found in animal cells.
1 ……
2 ……
[2]
(ii) Using features visible in Fig. 1.1, identify the group in the plant kingdom that species X and Y belong to.
Explain your answer.
species X ……
species Y ……
[4]
(iii) Understanding evolutionary relationships between crop plants can help scientists and farmers improve agriculture.
Explain how a scientist could determine if different crop plant species share a recent ancestor (are closely related).
…… [2]
[Total: 10]
* 0000800000004 * DFD
4
Mark scheme
1(a) genus AND species ; 1
1(b) fungus / fungi ; 1
1(c)(i) any two from: 2
1 chloroplast ;
2 cell wall ;
3 (large permanent) vacuole ;
4 AVP ; e.g. starch grains
1(c)(ii) any four from: 4
species X
1 fern ;
2 spores ;
3 fronds ;
species Y
4 monocotyledon ;
5 narrow / long / AW, leaves ;
6 parallel veins ;
1(c)(iii) any two from: 2
1 use, base / amino acid / nucleotide / gene, sequences OR sequence,
DNA / RNA / AW ;
2 (crops with) recent ancestors / closely related species, will have more,
sequences / genes / alleles in common / will have similar,
sequences / genes / alleles ;
3 AVP ;
Chickens are birds that are bred by farmers to produce eggs and meat. Modern farmed chickens are very different from the red junglefowl that is their wild ancestor.
Table 2.1 describes some of the characteristics of red junglefowl and farmed chickens.
Table 2.1
mean body mean number mean mass of mean age at type of bird mass / g of eggs per year pectoral muscle / g maturity / days red junglefowl 775 12 91 142
chicken 4090 160 437 59
(a) (i) Using Table 2.1, calculate the percentage change in the mean body mass from the red junglefowl to the chicken.
Give your answer to three significant figures.
Space for working.
…… % [3]
(ii) Suggest reasons why farmers have selectively bred chickens to reach maturity faster than red junglefowl.
…… [2]
(iii) Describe how a farmer could breed chickens with a larger body mass.
…… [3]
* 0000800000005 * DFD
5
(b) Chicken faeces can be used as a fertiliser.
Chicken faeces spread on agricultural land near lakes can act as a pollutant, and cause the destruction of the freshwater habitat.
Explain how the use of chicken faeces near freshwater lakes can lead to habitat destruction.
…… [6]
(c) Chicken waste contains a substance that is similar to urea.
Explain how urea is made in humans.
…… [3]
[Total: 17]
* 0000800000006 * DFD
6
Mark scheme
2(a)(i) 428 (%) ;;; 3 MP1 correct selection of data i.e. 4090
and 775 OR 3315 and 775
MP2 correct calculation to any number
of significant figures e.g.
((4090 – 775) ÷ 775) × 100 = 427.742
MP3 correct rounding to three
significant figures
ecf from previous MP
2(a)(ii) any two from: 2
1 (chickens) can produce eggs, sooner / at an earlier age / younger / AW ; ora
2 chicken reach, saleable size / have (more) meat, sooner / at an earlier
age / younger / AW ; ora
3 (chickens) can produce, chickens / chicks / offspring, sooner / at an earlier
age / younger / AW ; ora
4 increased / AW, profit ; ora
5 AVP ; e.g. to meet (high) demand for human
consumption
2(a)(iii) 1 breed / cross, chickens with the large(st) body mass together ; 3
2 select offspring with the large(st) body mass to breed together ;
3 (this process is) repeated for (many) generations ;
4 AVP ; e.g. ref. to artificial insemination
2(b) any six from: 6
1 run-off / washed into freshwater / AW ;
2 chicken manure contains (increased availability of), nitrate / (mineral) ions ;
3 eutrophication ;
4 increased / rapid, growth of, producers / AW ;
5 increased decomposition of dead, producers / AW ;
6 increased aerobic respiration by (decomposers) ;
7 (increased respiration causes a) reduction in (dissolved) oxygen (in water) ;
8 death / migration / AW, of, (named aquatic) organisms requiring (dissolved)
oxygen ;
9 AVP ;; e.g. (algal bloom / AW) results in other
(named) limiting factors of
photosynthesis / spread of diseases
from faeces in water
2(c) any three from: 3
deamination ;
of excess amino acids ;
(deamination) in the liver ;
the removal of the nitrogen-containing part (of the amino acid) ;
(a) Describe the pathway a water molecule takes from the soil to reach the xylem.
…… [2]
(b) A student investigated the effect of temperature on transpiration.
The student collected four small plants and placed them in beakers filled with water.
Fig. 3.1 shows the apparatus used.
layer of oil
water
beaker
114.22
Fig. 3.1
For each plant, the student measured the initial masses of the equipment, water and plant.
Each plant was placed in a different temperature-controlled room for three hours.
After three hours, the student measured the final masses of the equipment, water and plants.
* 0000800000007 * DFD
7
The results are shown in Table 3.1.
Table 3.1
transpiration rate temperature / °C initial mass / g final mass / g
/ g per hour
15 138.2 135.5 0.9
20 136.1 132.5 1.2
25 137.8 128.5 3.1
30 135.7 118.3
(i) Using the information in Table 3.1, calculate the transpiration rate in the plant kept at
30 °C.
…… g per hour [1]
(ii) Describe and explain the difference in the results for the plants kept at 15 °C and 25 °C.
…… [4]
* 0000800000008 * DFD
8
(iii) The investigation was repeated with a plant kept at 25 °C in a lower humidity environment.
Predict the effect of these conditions on the transpiration rate.
Explain your prediction.
…… [2]
(iv) Complete the sentences about water movement through the xylem.
The xylem transports water and …… .
Xylem cells form a long continuous …… with thick walls
containing cellulose and …… .
Water moves upwards in the xylem because of transpiration …… .
This draws up a …… of water molecules, held together by
…… between water molecules.
[6]
(c) (i) Explain why wilting occurs.
…… [3]
* 0000800000009 * DFD
9
(ii) Marram grass, Ammophila arenaria, is a xerophyte.
Fig. 3.2 is a photomicrograph of a cross-section of a marram grass leaf.
Fig. 3.2
Explain one way that the marram grass leaf shown in Fig. 3.2 is adapted to reduce transpiration.
…… [2]
[Total: 20]
* 0000800000010 * DFD
10
Mark scheme
3(a) any two from: 2
(enters) the root hair (cell) ;
moves through the (root) cortex (cells to the xylem) ;
AVP ; e.g. through a partially permeable / cell
(surface), membrane (by
osmosis / diffusion)
3(b)(i) 5.8 (g per hour) ; 1
3(b)(ii) any four from: 4
1 as temperature increases, water loss / transpiration, increases ; ora
2 comparative data manipulation with units ;
3 higher kinetic energy (of water molecules) / description of molecules having
more energy to, move / collide / AW ; ora
4 increases (the rate of) evaporation (inside leaf) ; ora
5 water evaporates from the surface of mesophyll cells ;
6 increases (the rate of) diffusion (of water vapour) through the stomata ; ora
7 more stomata open / stomata open wider, at high(er) temperatures ; ora
3(b)(iii) increased rate of transpiration ; 2
increased concentration gradient (of water vapour for diffusion through the
stomata) ;
3(b)(iv) 1 (mineral) ions ; 6
2 tube / vessel / AW ;
3 lignin ;
4 pull ;
5 column / AW ;
6 forces (of attraction) / attraction / AW ;
3(c)(i) any three from: 3
1 (plants / cells) exposed to, extreme heat / high temperatures ;
2 (plants / cells have) inadequate / not enough / no, water OR dehydration ;
3 (rate of) water uptake is less than, (rate of) water loss / transpiration ; ora
4 water moves out of cells (by osmosis) ;
5 cells, become flaccid / lose turgor (pressure) / plasmolyse ;
6 ref. to plants / leaves / cells, rely on (turgor) pressure of water on (inelastic)
cell walls for, (structural) support
/ to stay firm / AW ;
7 AVP ; e.g. wilting can occur because of a
nutrient deficiency
3(c)(ii) any one from: 2
1 inner surface of leaf is folded / AW ;
2 hairs / AW ;
3 sunken stomata or stomata in, pits / AW ;
any two from:
4 trap moist air / water vapour / reduce air, flow / movement ;
5 reduce water (vapour) diffusion gradient (out of stomata) ;
OR
6 curled / rolled / AW, leaf ;
7 (rolling) traps air / reduce air movement / shields leaf from heat / reduces
exposed surface ;
8 reduce water (vapour) diffusion gradient (out of stomata) ;
OR
9 few stomata ;
10 few sites where water exits the leaf / AW ;
OR
11 thick (waxy) cuticle ;
12 reduces evaporation (from the leaf surface) / creates a waterproof layer ;
Fig. 4.1 shows a section through a human heart and the main blood vessels.
B
N C
D
M
E
F
L
G
K
H
J
Fig. 4.1
(a) (i) State the letter in Fig. 4.1 that identifies:
the structure that separates oxygenated and deoxygenated blood ……
an atrioventricular valve. ……
[2]
(ii) Explain why the heart wall at H is thicker than the heart wall at D in Fig. 4.1.
…… [2]
* 0000800000011 * DFD
11
(iii) Table 4.1 contains eight descriptions of parts of the pathway a red blood cell takes as it moves from the vena cava to the aorta.
Using Fig. 4.1, complete Table 4.1 by numbering the descriptions to show the correct sequence.
Two have been done for you.
Table 4.1
description sequence
blood enters C
blood enters E and then E contracts
blood enters M and then M contracts 1
blood travels to lungs
blood moves into G
blood moves into B 8
N opens
blood moves into K
[2]
* 0000800000012 * DFD
12
(b) Fig. 4.2 shows the effect of exercise on heart rate.
exercise stops heart rate
exercise starts
time
Fig. 4.2
(i) Explain the effect of exercise on heart rate shown in Fig. 4.2.
…… [5]
* 0000800000013 * DFD
13
(ii) A lack of exercise can increase the risk of coronary heart disease.
State three other factors that can increase the risk of coronary heart disease.
1 ……
2 ……
3 ……
[3]
[Total: 14]
* 0000800000014 * DFD
14
Mark scheme
4(a)(i) J; 2 R each additional letter
F;
4(a)(ii) any two from: 2
1 (left ventricle / H) contains more muscle ; ora
2 (muscle) contracts / pumps, with more force ; ora
3 (contraction) creates a high(er) pressure ; ora
4 blood (leaving the ventricle) is required to move further / out of the heart / to
aorta / to the (whole) body / left atrium is only pushing blood to the ventricle ;
4(a)(iii) 2 all correct = 2 marks
description sequence
four correct / only 2 wrong = 1 mark
blood enters C 4
blood enters E and then E contracts 6
blood enters M and then M contracts 1
blood travels to lungs 5
blood moves into G 7
blood moves into B 8
N opens 3
blood moves into K 2
;;
4(b)(i) any five from: 5
1 (exercise can lead to release of) adrenaline that increases heart rate ;
2 (exercise results in) increased (rate of) blood (flow) to muscle (cells) ;
3 needed for (delivery of), oxygen / glucose OR removal of carbon dioxide ;
4 respiration releases energy ;
5 energy required for (muscle) contraction ;
6 (exercise can lead to) anaerobic respiration / production of, lactic
acid / lactate ;
7 correct ref. to oxygen debt ;
8 (heart rate remains high after exercise) to remove, lactic acid / lactate
(quickly) from muscles / to liver OR to continue supplying oxygen (to repay
the oxygen debt) ;
9 lactic acid / lactate, broken down / (aerobically) respired / converted to
glucose / carbon dioxide and water / oxidised, in liver;
10 AVP ; e.g. increased, carbon dioxide / acidity,
in the blood increases heart rate
4(b)(ii) any three from: 3
1 diet OR a diet high in, salt / saturated fats / cholesterol ;
2 (uncontrolled) stress ;
3 smoking (tobacco) ;
4 genetic (predisposition) ;
5 (old) age ;
6 sex ;
7 and 8 AVP ;; e.g. high blood pressure / excessive
alcohol consumption / obesity
(a) (i) State the balanced chemical equation for photosynthesis.
…… [2]
(ii) Chlorophyll is needed for photosynthesis.
State the name of the mineral ion needed to make chlorophyll.
…… [1]
(iii) State the name of the carbohydrate used for energy storage in a plant.
…… [1]
(b) A plant shoot was placed in a light-proof box. A hole was cut in one side of the box and a light was shone into the box.
Fig. 5.1 shows the plant shoot at the start of the investigation and after one week.
light proof box
light
plant shoot
start after one week
Fig. 5.1
(i) Identify the tropic response shown by the plant shoot in Fig. 5.1.
…… [1]
* 0000800000015 * DFD
15
(ii) Explain the chemical control of the tropic response shown by the plant shoot in Fig. 5.1.
…… [4]
(iii) Explain how the type of tropic response shown in Fig. 5.1 is an advantage to a plant.
…… [2]
[Total: 11]
* 0000800000016 * DFD
16
Mark scheme
5(a)(i) 6CO2 + 6H2O → C6H12O6 + 6O2 ;; 2 MP1 correct reactant and product
molecules
MP2 correct balancing of equation
5(a)(ii) magnesium (ion) ; 1
5(a)(iii) starch ; 1
5(b)(i) (positive) phototropism ; 1
5(b)(ii) any four from: 4
1 auxin ;
2 (auxin) is made in / released from, the (shoot) tip ;
3 (auxin) moves by diffusion from (the shoot tip) ;
4 (auxin) is concentrated on, shaded / left / AW, side of the, shoot / plant ;
5 (auxin) stimulates cell elongation ;
6 shaded / left / AW, side of shoot, elongates / bends / grows, more than,
light / right, side ;
5(b)(iii) 1 better chance of light reaching the plant / AW ; 2
any one from:
2 light provides energy ;
3 light is needed for photosynthesis ;
4 able to, produce more glucose / respire ;
(a) Fig. 6.1 is a diagram of the human male reproductive system.
G
A
F
B
E
D C
Fig. 6.1
Table 6.1 contains information about the male reproductive system shown in Fig. 6.1.
Complete Table 6.1.
Table 6.1
letter in Fig. 6.1 name of the structure function
scrotum
produces seminal fluid
transports urine and sperm
E
[4]
* 0000800000017 * DFD
17
(b) State the name of the hormone that causes voices to deepen at puberty.
…… [1]
(c) Sperm have adaptive features to carry out their function.
Explain three adaptive features of sperm.
1 ……
2 ……
3 ……
[3]
[Total: 8]
DFD
18
DFD
19
* 0000800000020 * DFD
20
Mark scheme
6(a) 4 one mark per correct row
letter in Fig. 6.1 name of the function
structure
C scrotum contains / protects / holds / AW,
testes / D
F prostate gland produces seminal fluid
A urethra transports urine and sperm
E sperm duct transport sperm (to urethra)
;;;;
6(b) testosterone ; 1
6(c) any three from: 3
1 flagellum / flagella, for, moving / swimming ;
2 mitochondria to release energy for, moving / swimming ;
3 acrosome to contain enzymes ;
4 enzymes to break down the jelly (coat of the egg) ;
5 haploid nucleus for fusing with the egg nucleus ;
6 streamlined, shape / head, for swimming / AW ;
Checked your answers against these? Let AI mark the whole paper, on your own working.
Examiners follow the generic marking principles at the front of the scheme, then each question's points: method (M), accuracy (A) and independent (B) marks, error carried forward where the scheme allows it, and positive marking, so you're credited for what you got right.
Check your answers against it
Done this paper? Upload your script and CIE Buddy's AI marker marks it question by question against this exact scheme, puts the ticks on your own working and says what each lost mark needed.
Where can I find the 0610/43 October/November 2025 mark scheme?+
On this page, free: the mark scheme for IGCSE Biology 0610/43, October/November 2025 (0610_w25_ms_43), and the question paper (0610_w25_qp_43), to read or download, with each question's marking points written out underneath.
How many marks is 0610/43 out of?+
Biology 0610/43 for October/November 2025 is out of 80 marks, with 1 hour 15 minutes to answer it, across 6 questions.
Can I get my 0610/43 answers marked?+
Yes. Upload your answers to 0610/43/O/N/25 as a PDF or photos, and CIE Buddy marks every question against this paper's official mark scheme, using Cambridge's marking rules. You get your score, each lost mark explained on your own script, and the topics to revise. It's a guide, not an official Cambridge grade.