IGCSE Science - Combined (0653) — May–June 2025, Paper 23

40 questions · every question answerable online with instant point-by-point AI marking against the official mark scheme.

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Question 1 · 1 mark · Characteristics and classification of living organisms - cell structure

Which structure is not found in animal cells? A cell wall B cytoplasm C nucleus D cell membrane

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Question 2 · 1 mark · Organisation of the organism - specialised cells

Palisade mesophyll cells are specialised cells. What is the function of these specialised cells? A photosynthesis B transport C reproduction D immunity

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Question 3 · 1 mark · Organisation of the organism - cell size and units

A human egg cell is 0.12 mm in diameter. How is this converted to a measurement in micrometres, μm? A multiply by 100 B multiply by 1000 C divide by 100 D divide by 1000

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Question 4 · 1 mark · Movement into and out of cells - osmosis

Which row about osmosis is correct? molecules that move details of movement type of permeable membrane --- --- --- --- A water from a dilute solution to a concentrated solution…

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Question 5 · 1 mark · Biological molecules - enzymes

The graph shows the activity of an enzyme at different temperatures. The curve of enzyme activity (vertical axis) against temperature/°C (horizontal axis, 0 to 60) rises from a…

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Question 6 · 1 mark · Plant nutrition / respiration - photosynthesis and respiration in the dark

An aquatic plant is in a test-tube of water. The test-tube is sealed and placed in the dark. The diagram shows a sealed test-tube containing water with an aquatic plant submerged…

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Question 7 · 1 mark · Human nutrition - diet and minerals

A pregnant woman is told she is deficient in iron. Which food increases the iron content in her diet? A cheese B rice C milk D red meat

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Question 8 · 1 mark · Human nutrition - digestion

Chemical digestion and physical digestion happen in various parts of the alimentary canal and associated organs. In which organ do both processes happen? A liver B mouth C…

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Question 9 · 1 mark · Human nutrition - chemical digestion and conditions

A test-tube is used to model the effect of protease on a protein suspension in the stomach. The diagram shows a test-tube containing protease and protein suspension at 37 °C. What…

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Question 10 · 1 mark · Transport in plants - transpiration

Water moves through the stomata of leaves during transpiration. Which row shows the direction of water movement and the form of the water? direction form --- --- --- A into the…

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Question 11 · 1 mark · Transport in animals - blood vessels

The diagrams show cross-sections of two different blood vessels. Vessel P is shown as a circular cross-section with a relatively thick wall and a small central lumen. Vessel Q is…

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Question 12 · 1 mark · Organisms and their environment - food webs and trophic levels

Which types of consumer describe the cat in this food web? 1 primary consumer 2 secondary consumer 3 tertiary consumer The food web shows: plant is eaten by sparrow, slug and…

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Question 13 · 1 mark · Organisms and their environment - ecosystems

What is an ecosystem? A a network of inter-connected food chains B a specific area in which a plant or an animal lives C all the plants and animals that live within a specific…

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Question 14 · 1 mark · States of matter / atoms - elements, compounds and mixtures

Which diagram represents molecules of a single compound? Each option shows a box containing particles drawn as open (white) circles and filled (black) circles bonded together. A…

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Question 15 · 1 mark · Atoms, elements and compounds - ions and ionic bonding

Which statement about ions is correct? A Atoms lose or gain electrons to form ions. B Ions are held together by strong attraction between negative ions. C Ions form when atoms…

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Question 16 · 1 mark · Acids, bases and salts - acids

Which formula does not represent an acid? A H₂SO₄ B HCl C HNO₃ D NH₃

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Question 17 · 1 mark · Electrolysis - electrodes and electrolytes

Apparatus used to electrolyse molten lead(II) bromide is shown. The diagram shows a d.c. power supply connected to two electrodes dipping into a container of molten liquid. The…

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Question 18 · 1 mark · Energy changes in chemical reactions - reaction pathway diagrams

The reaction pathway diagram for a reaction is shown. The vertical axis is energy and the horizontal axis is progress of reaction. Three energy levels are marked X (lowest, the…

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Question 19 · 1 mark · Rate of reaction - factors affecting rate

Calcium carbonate pieces react with dilute hydrochloric acid. Which change decreases the rate of the reaction? A Add a catalyst. B Decrease the temperature. C Increase the…

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Question 20 · 1 mark · Acids, bases and salts - preparation of insoluble salts

Barium sulfate is an insoluble salt. It is made when aqueous barium chloride reacts with compound W. Which row identifies compound W and the method used to obtain barium sulfate…

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Question 21 · 1 mark · The Periodic Table - Group VII / displacement reactions

Aqueous chlorine is added to colourless aqueous potassium bromide. The diagram shows a dropper adding aqueous chlorine into a test-tube containing aqueous potassium bromide. Which…

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Question 22 · 1 mark · Metals - alloys and metallic structure

Which diagram represents the structure of an alloy? A shows a regular lattice of alternating positive (+) and negative (–) ions (an ionic compound). B shows a close-packed…

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Question 23 · 1 mark · Air quality and climate - carbon dioxide and climate change

Which graph explains why scientists are concerned about climate change? Each option plots concentration of carbon dioxide in the atmosphere (vertical axis) against year…

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Question 24 · 1 mark · Organic chemistry - homologous series (alkanes)

Methane, ethane and propane are all members of the same homologous series. Which statement about these compounds is correct? A They contain double carbon–carbon covalent bonds. B…

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Question 25 · 1 mark · Experimental techniques and chromatography - Rf values

The diagram shows a chromatogram for a brown ink. The chromatography paper has a baseline at 0 cm where the brown ink spot was placed, and the solvent front is at 14 cm. Three…

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Question 26 · 1 mark · Organic chemistry - fractional distillation of petroleum

Which row describes the properties of fractions obtained from petroleum, from the bottom of the fractionating column to the top? chain lengths boiling points --- --- --- A…

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Question 27 · 1 mark · Metals - extraction of iron in the blast furnace

Iron is extracted from hematite in the blast furnace. Which row shows the substance that reduces iron(III) oxide and the source of this substance in the blast furnace? substance…

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Question 28 · 1 mark · Motion, forces and energy - free fall and kinematics

On planet R, there is no atmosphere and the acceleration of free fall g is 4.5 m/s². A rock of mass 2.0 kg falls from rest on planet R and hits the ground 4.0 m below. What is the…

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Question 29 · 1 mark · Motion, forces and energy - speed-time graphs

The diagram shows a speed–time graph for the motion of a car. The graph plots speed (vertical axis) against time (horizontal axis). The line starts at the origin and rises with a…

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Question 30 · 1 mark · Motion, forces and energy - work, energy and power

A boy runs up some stairs to get to the top. Which two quantities on their own are used to calculate the useful power transferred? A his weight and the height of the stairs B his…

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Question 31 · 1 mark · Thermal physics - convection

The diagram shows equipment used to demonstrate convection in air. Point X is labelled. A box with two chimneys on top sits over a base chamber. A burning candle is placed at the…

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Question 32 · 1 mark · States of matter - particle model

Which states of matter contain particles that are close together? A solids, liquids and gases B liquids and gases only C solids and gases only D solids and liquids only

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Question 33 · 1 mark · Thermal physics - evaporation

Which two factors both increase the rate at which a shallow pool of water evaporates? A greater surface area and higher temperature B greater surface area and lower temperature C…

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Question 34 · 1 mark · Waves - wave speed, frequency and wavelength

The diagram shows a section of a rope. Four wave crests pass a point on the rope every second. Each wave crest travels 80 cm in one second. The diagram shows a transverse wave on…

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Question 35 · 1 mark · Waves - transverse and longitudinal waves

Which statement about waves is correct? A In a longitudinal wave, the vibration of the particles is at right angles to the direction of the wave. B In a sound wave, the vibration…

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Question 36 · 1 mark · Waves - speed of sound in different media

A student measures the time taken for sound to travel a distance of 1.0 m in air, in water and in steel. The student puts the three materials in order of time taken, from shortest…

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Question 37 · 1 mark · Electricity and magnetism - measuring instruments / scales

The diagram shows the scale of an analogue voltmeter. The scale runs from 0 to 0.5 V with major divisions marked at 0, 0.1, 0.2, 0.3, 0.4 and 0.5 V, each major division subdivided…

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Question 38 · 1 mark · Electricity and magnetism - Ohm's law / resistance

What is the relationship between the current in a resistor, the potential difference (p.d.) across it and its resistance? A current = p.d. / resistance B current = (p.d.)² /…

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Question 39 · 1 mark · Electricity and magnetism - current in parallel circuits

The diagram shows two resistors connected to a battery. Two resistors are connected in parallel. The total current from the battery in the main circuit is 6.0 A. The current in…

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Question 40 · 1 mark · Space physics - life cycle of stars

The life cycle of a star depends on whether it has a small mass, a large mass or a very large mass. Which stars have a supernova as one of the later stages in their life cycles? A…

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