IGCSE Biology 0610/31 May/June 2025 Past Paper with Answers

Question 1

Five specialised cells are labelled A to E: A is a disc-shaped cell with no nucleus, B is a long branched cell with thin fibre-like extensions, C is a plant cell with a long thin projection, D is a cell with a head, a tip structure and a long tail, and E is a rectangular green plant cell full of chloroplasts. Which set of identifications correctly states the cell containing an acrosome, the cell containing haemoglobin, the two cells found in plants, and the cell found in the peripheral nervous system?

1. acrosome in D, haemoglobin in A, found in plants C and E, peripheral nervous system B
2. acrosome in A, haemoglobin in D, found in plants B and C, peripheral nervous system E
3. acrosome in B, haemoglobin in E, found in plants A and D, peripheral nervous system C
4. acrosome in D, haemoglobin in B, found in plants A and E, peripheral nervous system C

Question 2

A red blood cell does not contain a nucleus. What is the function of the nucleus in a cell?

1. it contains the genetic material and controls the cell’s activities
2. it releases energy from glucose during respiration
3. it controls what substances enter and leave the cell
4. it is where photosynthesis takes place

Question 3

Some structures are found in every living cell, both animal and plant. Which pair of structures is present in all of these cells?

1. cell membrane and cytoplasm
2. cell wall and chloroplasts
3. chloroplasts and a large vacuole
4. cell wall and a permanent vacuole

Question 4 · Answer A

Step 1: The long projection gives the root hair cell a large surface area. Step 2: This large surface area, together with a large permanent vacuole, speeds up the uptake of water and mineral ions from the soil. Step 3: Chloroplasts are for photosynthesis, a waxy layer reduces water loss in leaves, and cilia move mucus, so none of these fit a root hair cell.

Question 5 · Answer A

Step 1: Actual size = image size ÷ magnification, so both the image size and the magnification are needed. Step 2: Measuring the image and knowing the magnification lets you calculate the real length. Step 3: The number of cells, the stain colour and the cell width do not appear in this calculation.

Question 6 · Answer A

Step 1: The bubble count rises (5→21) as carbon dioxide increases, and carbon dioxide is a raw material used in photosynthesis. Step 2: The count is 21 at both 0.4 and 0.5, so it stays the same between 0.4 and 0.5 arbitrary units, and the gas released as bubbles is oxygen. Step 3: Keeping the lamp at a fixed distance keeps the light intensity constant, so the correct set is increases; raw; 0.4 and 0.5; oxygen; intensity.

Question 7 · Answer A

Step 1: The green pigment is chlorophyll, found in the chloroplasts. Step 2: Chlorophyll absorbs light energy and transfers it to chemical reactions. Step 3: This energy is used to make carbohydrates such as glucose in photosynthesis, so chlorophyll is essential for the plant’s nutrition.

Question 8 · Answer A

Step 1: Respiration breaks down glucose to release energy and produces carbon dioxide as a waste gas. Step 2: Plants respire all the time, so respiration is the process that produces carbon dioxide. Step 3: Photosynthesis uses carbon dioxide, while transpiration is water loss and translocation moves sugars, so none of these produce carbon dioxide.

Question 9 · Answer A

Step 1: Physical digestion (churning) occurs in the stomach, which also releases hydrochloric acid. Step 2: The pancreas secretes the enzymes protease and amylase into the small intestine. Step 3: The pancreas also secretes the hormone insulin, so the order is stomach; stomach; pancreas; pancreas.

Question 10 · Answer A

Step 1: Hydrochloric acid kills many of the microorganisms taken in with food. Step 2: It also makes the stomach contents acidic, giving the optimum (low) pH for the protease enzymes in the stomach to work. Step 3: Bile emulsifies fats, the small intestine absorbs food, and blood carries gases, so these are not functions of stomach acid.

Question 11 · Answer A

Step 1: Protease is an enzyme that digests large protein molecules. Step 2: It breaks proteins down into amino acids, which are small and soluble. Step 3: Being small and soluble, the amino acids can be absorbed into the blood, so protease is important for making proteins absorbable.

Question 12 · Answer A

Step 1: Iodine solution turns blue-black when starch is present and stays yellow-brown when it is not. Step 2: Tube X has starch only, so it turns blue-black. Step 3: In tube Y the amylase digests the starch into sugars, so no starch remains and the iodine stays yellow-brown.

Question 13 · Answer A

Step 1: Iodine only turns blue-black if starch is present. Step 2: In Y the amylase has broken the starch down into sugars, so no starch is left and the colour is different. Step 3: In X there is no amylase, so the starch remains and gives the blue-black colour, which is why the two tubes differ.

Question 14 · Answer A

Step 1: Sense organs are made of receptor cells that detect changes. Step 2: The changes they detect are called stimuli. Step 3: Common stimuli include light, sound, touch, temperature and chemicals, so the missing stimulus in the list is sound, giving receptor; stimuli; sound.

Question 15 · Answer A

Step 1: In dim light the circular muscles of the iris relax and the radial muscles contract, so the pupil widens (its diameter increases). Step 2: A wider pupil lets more light into the eye. Step 3: This extra light helps the person to see in the dim conditions, so the pupil widens to allow more light in.

Question 16 · Answer A

Step 1: The blind spot is the part of the retina that contains no light receptor cells. Step 2: This is the point where the optic nerve leaves the back of the eye. Step 3: The cornea, iris and lens are at the front of the eye and are not the blind spot, which is at the back where the nerve exits.

Question 17 · Answer A

Step 1: Part P behind the pupil is the lens, which changes shape to focus light onto the retina. Step 2: Part Q lining the back of the eye is the retina, which contains the light receptors. Step 3: Part R is the optic nerve, which carries impulses to the brain, so P focuses, Q detects and R carries impulses.

Question 18 · Answer A

Step 1: The biggest percentage change is +7.55 at 0.10 mol per dm³, so that cylinder showed the largest change. Step 2: At 1.00 mol per dm³ the mass falls (−5.28), because water leaves the cylinder by osmosis into the more concentrated solution. Step 3: All the mass changes happen because water crosses the partially permeable cell membranes, so those three conclusions are correct.

Question 19 · Answer A

Step 1: Water moves across a partially permeable membrane from a dilute to a more concentrated solution. Step 2: This movement of water is called osmosis. Step 3: Active transport moves ions against a gradient using energy, respiration releases energy, and transpiration is water loss from leaves, so the process here is osmosis.

Question 20 · Answer A

Step 1: Higher temperature gives water molecules more energy, speeding up osmosis. Step 2: A larger surface area of the cylinders lets water cross the membranes faster. Step 3: Colour, time of day, beaker mass and other irrelevant factors do not affect the rate, so temperature and surface area are the influencing factors.

Question 21 · Answer A

Step 1: As water enters, the plant cell swells and presses outwards on its surroundings. Step 2: The strong cellulose cell wall is rigid and resists this pressure, stopping the cell from bursting. Step 3: The membrane, cytoplasm and nucleus cannot provide this support, so it is the cell wall that prevents bursting.

Question 22 · Answer A

Step 1: Water dissolves many substances, so it acts as a solvent in the body. Step 2: Blood, which is mostly water, transports dissolved substances around the body, so water is used for transport. Step 3: Enzymes are proteins, genetic material is DNA, and phagocytosis is carried out by white blood cells, so those are not uses of water.

Question 23 · Answer A

Step 1: A balanced diet provides carbohydrates, proteins, fats, vitamins, minerals, fibre and water. Step 2: Carbohydrate and protein are two of these named components. Step 3: Oxygen and carbon dioxide are gases, urea and bile are body wastes/secretions, and haemoglobin and insulin are made in the body, so none of these are dietary components.

Question 24 · Answer A

Step 1: Arteries have thick muscular walls and a narrow lumen to withstand high pressure, so vessel Z is an artery. Step 2: Veins have thinner walls and a large lumen to carry blood at low pressure, so vessel X is a vein. Step 3: Capillaries have very thin walls (one cell thick) and a very narrow lumen, so vessel Y is a capillary.

Question 25 · Answer A

Step 1: Veins contain valves that arteries and capillaries do not have. Step 2: Because blood in veins is at low pressure, these valves stop the blood flowing backwards. Step 3: They ensure a one-way flow of blood back to the heart; valves do not pump, and cilia and villi are found elsewhere.

Question 26 · Answer A

Step 1: The pulmonary vein returns blood from the lung to the heart, so organ A is the lung and the central pump, organ B, is the heart. Step 2: The large vessel leaving the heart to the body is the aorta, so vessel C is the aorta. Step 3: The vessel carrying blood from a kidney back to the heart is the renal vein, so vessel D is the renal vein.

Question 27 · Answer A

Step 1: The kidneys filter the blood and remove urea, a waste made in the liver. Step 2: They also remove excess water and excess mineral ions to keep the body balanced. Step 3: Glucose and amino acids are reabsorbed, gases are exchanged in the lungs, and cells and proteins are too large to be filtered, so the kidneys excrete urea and excess water.

Question 28 · Answer A

Step 1: An organ system is a group of organs working together, such as the nervous system and the respiratory (gas exchange) system. Step 2: Other human organ systems include the reproductive, excretory and endocrine systems. Step 3: Chloroplasts and vacuoles are cell parts, haemoglobin and enzymes are molecules, and xylem and phloem are plant tissues, so they are not human organ systems.

Question 29 · Answer A

Step 1: There are 10 millimetres in 1 centimetre. Step 2: So 0.5 cm = 0.5 × 10 = 5 mm. Step 3: The smallest macroplastic is therefore 5 mm in diameter.

Question 30 · Answer A

Step 1: The macroplastic mass is zero until 1970 and then increases. Step 2: The microplastic mass increases to a maximum in 2000 and then decreases. Step 3: So macroplastics rise from 1970 onwards while microplastics rise then fall, peaking in 2000.

Question 31 · Answer A

Step 1: Animals may mistake floating plastic for food and eat it, which can block or damage their gut. Step 2: Animals can also become trapped or tangled in larger pieces of plastic, which can injure or suffocate them. Step 3: Plastic is not a food or a benefit, so the harmful effects are being eaten and trapping animals.

Question 32 · Answer A

Step 1: Pollution adds harmful substances to water. Step 2: Fertiliser washed off farmland (or untreated sewage) adds nutrients that pollute the water and can cause eutrophication. Step 3: Oxygen from plants, rainwater and sunlight are natural and do not pollute, so the source of pollution is fertiliser.

Question 33 · Answer A

Step 1: The characteristics of living organisms are movement, respiration, sensitivity, growth, reproduction, excretion and nutrition. Step 2: Respiration and growth are two of these characteristics. Step 3: Evaporation, condensation, magnification, dilution, filtration and distillation are physical or laboratory processes, not life processes, so the answer is respiration and growth.

Question 34 · Answer A

Step 1: The female gamete (sex cell) is the egg cell, made in the ovary. Step 2: It is released ready to be fertilised by a sperm. Step 3: The sperm is the male gamete, a zygote forms after fertilisation, and an embryo is a later stage, so the female sex cell is the egg cell.

Question 35 · Answer A

Step 1: Fertilisation is the joining (fusion) of a male gamete nucleus with a female gamete nucleus. Step 2: When a sperm nucleus fuses with an egg nucleus, this is fertilisation. Step 3: Pollination is in flowering plants, germination is a seed growing, and menstruation is loss of the uterus lining, so the process is fertilisation.

Question 36 · Answer A

Step 1: When the sperm and egg nuclei fuse, a single cell called the zygote is formed. Step 2: The zygote then divides to form an embryo. Step 3: A gamete is a sex cell before fertilisation, and an embryo and foetus are later stages, so the cell formed straight after fertilisation is the zygote.

Question 37 · Answer A

Step 1: After fertilisation the zygote divides repeatedly as it moves down the oviduct. Step 2: It becomes a hollow ball of cells (stage 4) by the time it reaches the uterus. Step 3: This hollow ball implants (embeds) into the thick uterus lining, so stage 4 is the stage that implants.

Question 38 · Answer A

Step 1: The disc-shaped structure attached to the uterus wall is the placenta, so part X is the placenta. Step 2: The long twisted tube connecting the fetus to the placenta is the umbilical cord, so part Y is the umbilical cord. Step 3: The amniotic sac surrounds the fetus and the ovary and oviduct are elsewhere, so X is the placenta and Y is the umbilical cord.

Question 39 · Answer A

Step 1: Part Z is the amniotic sac, which is filled with amniotic fluid around the fetus. Step 2: This fluid cushions the fetus and protects it from mechanical damage (and helps keep its temperature steady). Step 3: Exchange of oxygen and food is the placenta’s job, the ovary releases eggs, and testes make sperm, so the sac’s function is to protect the fetus.