IGCSE Biology 0610/12 May/June 2025 Past Paper with Answers

Question 1

A herbivore sees a carnivore approaching and reacts to this change in its surroundings. Which characteristic of living organisms is involved when the herbivore detects and responds to the carnivore?

1. sensitivity
2. excretion
3. growth
4. reproduction

Question 2

The binomial system gives each organism a two-part Latin scientific name made of its genus and species. Which of these names has been written using the binomial system?

1. Vulpes vulpes
2. Brown seaweed
3. Polar bear
4. Red fox

Question 3

Arthropods are animals with an exoskeleton and jointed legs, and they include insects, arachnids, crustaceans and myriapods. Which list contains only groups of arthropods?

1. arachnids, crustaceans, myriapods
2. amphibians, insects, myriapods
3. crustaceans, insects, fish
4. insects, myriapods, reptiles

Question 4 · Answer A

Step 1: Photosynthesis takes place in chloroplasts, which contain the green pigment chlorophyll. Step 2: Chlorophyll traps light energy for photosynthesis, so the chloroplast is the site of photosynthesis. Step 3: The nucleus controls the cell, the cell wall gives support, and the vacuole stores cell sap, so none of these carries out photosynthesis.

Question 5 · Answer A

Step 1: Actual length = image length divided by magnification. Step 2: X gives 0.20 ÷ 50 = 0.0040 mm; Y gives 0.50 ÷ 150 = 0.0033 mm; Z gives 0.40 ÷ 250 = 0.0016 mm. Step 3: Putting these from smallest to largest gives Z (0.0016), then Y (0.0033), then X (0.0040), so the order is Z, Y, X.

Question 6 · Answer A

Step 1: Osmosis is the net movement of water molecules from a dilute solution (more water) to a concentrated solution (less water) through a partially permeable membrane. Step 2: The left side is dilute and the right side is concentrated, so water moves overall from left to right. Step 3: The dissolved substance cannot pass through the partially permeable membrane, so the options about the dissolved substance moving are wrong.

Question 7 · Answer A

Step 1: Fats and oils are built from glycerol and fatty acids, so glycerol is a basic unit of oils. Step 2: Carbohydrates such as glycogen are built from simple sugars, and proteins are built from amino acids. Step 3: So the other statements pair the wrong basic units with their molecules; only glycerol as a unit of oils is correct.

Question 8 · Answer A

Step 1: The biuret test for protein gives a positive result by turning from blue to purple. Step 2: A purple colour therefore shows protein is present. Step 3: Blue-black is the iodine test for starch, brick red is the Benedict test for reducing sugar, and blue is the negative biuret colour.

Question 9 · Answer A

Step 1: Photosynthesis uses carbon dioxide and water as its raw materials. Step 2: Using light energy, these are converted into glucose and oxygen. Step 3: Glucose and oxygen are products of photosynthesis, not raw materials, so any option containing glucose as a raw material is wrong.

Question 10 · Answer A

Step 1: Magnesium ions are needed to make chlorophyll, so without them chlorophyll production decreases. Step 2: Chlorophyll is the green pigment, so with less chlorophyll the leaves cannot be fully green and turn yellow. Step 3: So a lack of magnesium causes chlorophyll production to decrease and the leaves to be yellow.

Question 11 · Answer A

Step 1: The flat surface layer at the top of the leaf is the upper epidermis, so tissue 1 is the epidermis. Step 2: The tall, closely packed column-shaped cells just below it are the palisade mesophyll, so tissue 2 is the palisade mesophyll. Step 3: The rounded, loosely packed cells with air spaces beneath are the spongy mesophyll, so tissue 3 is the spongy mesophyll.

Question 12 · Answer A

Step 1: Plant material such as vegetables, fruit and cereals is rich in dietary fibre. Step 2: So a diet with a lot of plant material will supply plenty of fibre, which is therefore unlikely to be deficient. Step 3: Meat is a major source of protein, fat and vitamin D, so cutting out meat makes these more likely to be lacking.

Question 13 · Answer A

Step 1: The roots of the teeth sit in sockets in the jaw bone and are surrounded by the gums. Step 2: So the teeth are embedded in the gums and the bone. Step 3: Enamel, dentine, cement and pulp are parts of the tooth itself, not the structures the tooth is embedded in.

Question 14 · Answer A

Step 1: Amylase is made by the salivary glands and the pancreas. Step 2: Pancreatic amylase is released into the small intestine, where it digests starch into maltose, so amylase acts in the small intestine. Step 3: The stomach makes protease, the large intestine absorbs water, and the oesophagus only carries food down, so amylase does not act in these parts.

Question 15 · Answer A

Step 1: The small intestine absorbs the digested food (and a lot of water) into the blood. Step 2: The colon (large intestine) mainly absorbs the remaining water. Step 3: So the colon absorbs water, while the small intestine absorbs both digested food and water.

Question 16 · Answer A

Step 1: Inside the leaf, liquid water turns into water vapour at the cell surfaces, which is evaporation, so process 1 is evaporation. Step 2: The water vapour then moves from a high concentration in the leaf to a lower concentration outside through the stomata, which is diffusion, so process 2 is diffusion. Step 3: Osmosis is the movement of liquid water across membranes, so it does not describe either process here.

Question 17 · Answer A

Step 1: The pump in the circulatory system is the organ that pushes blood out to the rest of the body. Step 2: The heart is a muscular organ that contracts to pump blood out to all the other organs, so the heart is the pump. Step 3: The lungs, kidneys and brain receive blood from the heart but do not pump it around the body.

Question 18 · Answer A

Step 1: A vessel carrying blood towards the heart is a vein. Step 2: The vein that brings blood from the lungs to the heart is the pulmonary vein. Step 3: The aorta and pulmonary artery carry blood away from the heart, and the vena cava brings blood from the body, not the lungs.

Question 19 · Answer A

Step 1: Pathogens are spread on dirty hands and contaminated food, so good hygiene reduces their spread. Step 2: Washing hands before and after handling raw food removes pathogens and stops them being passed on. Step 3: Leaving food uncovered, washing hands only after meals, and using the same equipment for raw and cooked food all let pathogens spread.

Question 20 · Answer A

Step 1: Carbon dioxide is tested using limewater, which turns from clear to milky (cloudy) when carbon dioxide is bubbled through it. Step 2: So limewater turning milky shows carbon dioxide is present. Step 3: DCPIP tests for vitamin C, ethanol is used in the test for fats, and iodine solution tests for starch.

Question 21 · Answer A

Step 1: In yeast, anaerobic respiration (fermentation) breaks down glucose to alcohol and carbon dioxide, while aerobic respiration does not make alcohol. Step 2: So only anaerobic respiration produces alcohol. Step 3: Both types produce carbon dioxide, only aerobic respiration produces water, and only aerobic respiration uses oxygen, so the other statements are wrong.

Question 22 · Answer A

Step 1: A ureter is the tube that carries urine from a kidney to the bladder. Step 2: So the narrow tube running from a kidney down to the bladder is the ureter. Step 3: The bean-shaped organ is the kidney, the muscular bag is the bladder, and the tube carrying urine out of the body is the urethra.

Question 23 · Answer A

Step 1: A structure in the skin that detects a stimulus such as heat is a receptor, so P is a receptor. Step 2: A neurone that carries the impulse from the receptor to the central nervous system is a sensory neurone, so Q is a sensory neurone. Step 3: Effectors (muscles or glands) carry out responses, and motor neurones carry impulses away from the central nervous system, so they do not match P or Q here.

Question 24 · Answer A

Step 1: The gland that sits on top of a kidney is the adrenal gland, which produces the hormone adrenaline, so gland 1 produces adrenaline. Step 2: The long gland lying in the loop of the duodenum is the pancreas, which produces the hormone insulin, so gland 2 produces insulin. Step 3: Amylase and lipase are digestive enzymes, not hormones, so options naming them are wrong.

Question 25 · Answer A

Step 1: Roots show positive gravitropism, growing in the direction of gravity, so the root grows downwards. Step 2: Shoots show negative gravitropism, growing against gravity, so the shoot grows upwards. Step 3: So a horizontal seedling responds by the root bending down and the shoot bending up.

Question 26 · Answer A

Step 1: The cap at the tip of the sperm head (the acrosome) contains digestive enzymes. Step 2: These enzymes break down the membrane of the egg cell so the sperm can fertilise it, so the tip of the head is the part containing enzymes. Step 3: The nucleus carries the genetic material, the middle piece contains mitochondria for energy, and the tail moves the sperm, so none of these store the digestive enzymes.

Question 27 · Answer A

Step 1: Testosterone is the male sex hormone and brings about male secondary sexual characteristics. Step 2: Growth of facial hair is a male characteristic caused by testosterone. Step 3: Breast development, the start of the menstrual cycle and widening of the hips are female characteristics caused by oestrogen, not testosterone.

Question 28 · Answer A

Step 1: Menstruation happens at the start of the cycle, so soon after day 0 the lining of the uterus is breaking down. Step 2: Ovulation happens around day 14, so at day 14 an ovary releases an egg. Step 3: After ovulation the uterus lining stays thick ready for a fertilised egg, so the later point shows a thick uterus lining being maintained.

Question 29 · Answer A

Step 1: A gene can exist in different versions, and each version is called an allele. Step 2: So an alternative form of a gene is an allele. Step 3: A chromosome is a thread of DNA carrying many genes, a genotype is the set of alleles an organism has, and a protein is a molecule made using a gene, so none of these is an alternative form of a gene.

Question 30 · Answer A

Step 1: Each heterozygous parent (for example Ff) can pass on either a normal allele or the recessive allele. Step 2: Crossing Ff with Ff gives offspring in the ratio 1 FF : 2 Ff : 1 ff, and only the ff child has cystic fibrosis. Step 3: One out of the four possible combinations is ff, so the probability is 1 in 4, which is 25%.

Question 31 · Answer A

Step 1: Continuous variation shows a range of values with no distinct groups, such as a measurement like mass. Step 2: Body mass in cats varies smoothly across a range, so it shows continuous variation. Step 3: ABO blood groups, seed colour and seed shape each fall into a few distinct categories, so they show discontinuous variation.

Question 32 · Answer A

Step 1: An adaptation to prevent predation should help the butterfly avoid being caught and eaten. Step 2: Spots that look like large eyes can startle or confuse a predator into thinking the butterfly is a bigger animal, helping it escape. Step 3: Flying slowly and being easier to see would make it more likely to be caught, and detecting nectar is about feeding, not avoiding predators.

Question 33 · Answer A

Step 1: Energy enters most ecosystems as light from the Sun. Step 2: Plants capture this light energy in photosynthesis, so the original source of energy is the Sun. Step 3: Photosynthesis and respiration are processes that transfer energy, not the source of it, and kinetic energy is energy of movement, not the input to ecosystems.

Question 34 · Answer A

Step 1: A producer makes its own food using energy from the Sun by photosynthesis. Step 2: In a food chain the producer is at the start, where energy first enters from the Sun, so the first organism is the producer. Step 3: The other organisms are consumers, because they get their energy by eating the organism before them in the chain.

Question 35 · Answer A

Step 1: Respiration releases carbon dioxide from living organisms into the atmosphere. Step 2: Arrow 2 (plants to the atmosphere) and arrow 4 (animals to the atmosphere) both add carbon dioxide to the air, so they represent respiration. Step 3: Arrow 1 (atmosphere to plants) is photosynthesis, and arrow 3 (plants to animals) is feeding, so they are not respiration.

Question 36 · Answer A

Step 1: The lag phase is the slow start of population growth, when numbers increase only a little. Step 2: On a sigmoid curve this is the low, almost flat part at the very beginning, so that part shows the lag phase. Step 3: The steep middle part is the rapid (exponential) growth phase, and the flat top is the stationary phase where the population has levelled off.

Question 37 · Answer A

Step 1: To find the activity causing the highest loss overall, compare the share for each activity across all three animal groups. Step 2: Habitat loss is the largest contributor in every animal group, so summed across the groups it causes the greatest species loss. Step 3: Exploitation, pollution and other factors each account for smaller shares, so habitat loss is the highest overall.

Question 38 · Answer A

Step 1: Bacteria are useful because they can make complex molecules such as proteins (statement 1) and because they reproduce very quickly to give large numbers fast (statement 2). Step 2: Having a cell wall (statement 3) is a general feature of bacteria and does not make them useful for biotechnology. Step 3: So only statements 1 and 2 explain their usefulness.

Question 39 · Answer A

Step 1: The rate rises to a peak at about 40 degrees Celsius and then falls, which is the pattern shown by enzymes that have an optimum temperature and are denatured by heat. Step 2: This suggests the washing powder contains enzymes. Step 3: The rate falls above 40 degrees, the optimum is about 40 degrees (not 10 to 30), and the rate is not directly proportional to temperature because it goes down after the peak, so the other statements are wrong.

Question 40 · Answer A

Step 1: Plant biomass is broken down to release the sugar glucose, so K is glucose. Step 2: Yeast is added to ferment the glucose by anaerobic respiration, so organism L is yeast. Step 3: Anaerobic respiration of glucose by yeast produces ethanol (alcohol), which is extracted as the biofuel, so M is ethanol.