Key words

A

Absorption When the energy of a sound is transferred to a material Sound

Absorption When the energy of light is transferred to a material Light

Acceleration How quickly speed increases or decreases Speed and motion

Acid Has a pH below 7 Acids and alkalis

Acidic oxide An oxide that makes an acid in water, such as carbon dioxide Metals and reactivity

Addiction Depending on a drug and finding it very hard to stop Drugs and health

Aerobic respiration Respiration that uses oxygen Respiration

Air resistance Drag from moving through air Forces

Alcohol A depressant found in drinks such as beer and wine Drugs and health

Alkali Has a pH above 7 Acids and alkalis

Alkali metals The reactive metals in Group 1 The periodic table

Alveoli Tiny air sacs at the ends of the bronchioles Breathing and gas exchange

Ammeter Measures current Electricity

Amniotic fluid The liquid around the foetus that protects it Human reproduction

Ampere The unit of current Electricity

Amplitude The height of a wave, from its middle line to a peak Sound

Anaerobic respiration Respiration without oxygen Respiration

Angle of incidence The angle between the incoming ray and the normal Light

Angle of reflection The angle between the outgoing ray and the normal Light

Antagonistic pair Two muscles that pull a bone in opposite directions Skeleton and muscles

Anther Makes the pollen Plant reproduction

Antibiotic A medicine that treats infections caused by bacteria Drugs and health

Area The size of a surface, in m² or cm² Pressure, moments and stretching

Artificial satellite A machine that people have put into orbit Gravity and space

Asthma A condition in which the airways sometimes get narrower Breathing and gas exchange

Atmosphere The layer of gases around the Earth Earth and atmosphere

Atmospheric pressure The push of the air, caused by the weight of the air above Pressure, moments and stretching

Atom The smallest particle of an element that can exist Elements, atoms and compounds

Atomic number The number that gives an element its place in the periodic table The periodic table

Attract Pull towards each other Magnets and electromagnets

Average speed Total distance divided by total time Speed and motion

Axis The imaginary line through the poles that the Earth spins around Gravity and space

B

Balanced diet Eating the right amount of each nutrient, with fibre and water Food and digestion

Balanced forces Equal and opposite forces on one object Forces

Ball and socket joint A joint that moves in almost every direction, like the hip Skeleton and muscles

Base Any substance that neutralises an acid Acids and alkalis

Basic oxide An oxide that neutralises acids, such as a metal oxide Metals and reactivity

Battery Two or more cells joined together Electricity

Biceps The muscle that bends the arm Skeleton and muscles

Bioaccumulation The build-up of a toxin inside living things Ecosystems

Biodiversity The variety of living things in a place Genetics and evolution

Boiling A liquid turning into a gas all through the liquid Particles and states of matter

Boiling point The temperature at which a liquid boils Particles and states of matter

Bone marrow Tissue inside some bones where new blood cells are made Skeleton and muscles

Breathing Moving air into and out of the lungs Breathing and gas exchange

Breathing Moving air into and out of the lungs Respiration

Breathing rate The number of breaths taken in one minute Breathing and gas exchange

Brittle Shatters when it is hit The periodic table

Bronchi Two tubes that carry air from the trachea into the lungs Breathing and gas exchange

Bronchioles Small tubes inside the lungs Breathing and gas exchange

Brownian motion The random jiggling of a tiny speck as particles hit it Particles and states of matter

C

Caffeine A stimulant found in coffee, tea and cola Drugs and health

Carbohydrate The body’s main source of energy: starch and sugars Food and digestion

Carbon cycle How carbon moves between the air, living things and the ground Earth and atmosphere

Carbon dioxide The gas made in aerobic respiration and in fermentation Respiration

Carbon dioxide The gas a plant takes in for photosynthesis Photosynthesis

Carbon dioxide A compound with one carbon atom joined to two oxygen atoms Elements, atoms and compounds

Carbon monoxide A poisonous gas that takes the place of oxygen in the blood Breathing and gas exchange

Carnivore An animal that eats only other animals Ecosystems

Carpel The female part of a flower: stigma, style and ovary Plant reproduction

Cartilage Smooth tissue on the ends of bones that reduces friction Skeleton and muscles

Catalyst Speeds up a reaction and is not used up Chemical reactions

Cell Smallest building block of a living thing Cells

Cell Pushes charge around a circuit Electricity

Cell membrane Controls what goes in and out Cells

Cell wall Tough layer that supports a plant cell Cells

Ceramic A hard, brittle material with a very high melting point Metals and reactivity

Chemical bond The force that holds atoms together in a molecule Chemical reactions

Chemical formula Symbols and numbers that show the elements in a substance and the ratio of their atoms Elements, atoms and compounds

Chemical property How a substance reacts with other substances The periodic table

Chemical reaction A change that rearranges atoms to make new substances Elements, atoms and compounds

Chemical reaction A change in which a new substance is made Chemical reactions

Chemical store The energy store in food, fuels and batteries Energy

Chemical symbol One or two letters that stand for an element Elements, atoms and compounds

Chloride A compound of an element with chlorine Elements, atoms and compounds

Chlorophyll The green substance that absorbs light Photosynthesis

Chloroplast The part of a plant cell where photosynthesis happens Photosynthesis

Chloroplasts Absorb light for photosynthesis Cells

Chromatography Separates dissolved coloured substances Separating mixtures

Chromosome A thread of tightly coiled DNA that carries many genes Genetics and evolution

Cirrhosis Scarring of the liver, which heavy drinking can cause Drugs and health

Combustion Burning: a reaction with oxygen that gives out heat and light Chemical reactions

Community All the populations that share a habitat Ecosystems

Compass needle A small magnet that can turn freely and lines up with the Earth’s field Magnets and electromagnets

Competition A struggle for the same food, water, light or space Ecosystems

Composite A material made by combining two or more materials Metals and reactivity

Compound Two or more elements chemically joined together Elements, atoms and compounds

Condenser Cools a gas so that it turns back into a liquid Separating mixtures

Condensing Changing from a gas to a liquid Particles and states of matter

Conduction Vibrating particles pass energy to their neighbours Energy

Conductor Lets electricity or heat pass through it easily The periodic table

Conductor Lets current flow through it easily Electricity

Conservation of energy Energy cannot be created or destroyed Energy

Conservation of mass The total mass is the same before and after a reaction Chemical reactions

Consumer An animal that eats plants or other animals Ecosystems

Contact force Acts only when objects touch Forces

Continuous variation Can take any value in a range, such as height Genetics and evolution

Contract When a muscle gets shorter and fatter, and pulls Skeleton and muscles

Convection A heated liquid or gas rises and carries energy with it Energy

Convex lens A lens, thicker in the middle, that bends rays towards each other Light

Core The centre of the Earth, made mostly of iron and nickel Earth and atmosphere

Core The piece of soft iron that a coil is wound round Magnets and electromagnets

Corrosive Can destroy skin and other materials Acids and alkalis

Craving A strong urge to take a drug again Drugs and health

Crust The thin, solid outer layer of the Earth Earth and atmosphere

Crystallisation Crystals forming from a solution Separating mixtures

Crystals Solid salt left after evaporation Acids and alkalis

Current A flow of electric charge Electricity

Cytoplasm Jelly where reactions happen Cells

D

Dalton’s model The idea that atoms are tiny solid balls that cannot be broken down Elements, atoms and compounds

Day The time the Earth takes to spin once on its axis Gravity and space

Decomposer Breaks down dead plants and animals, so nutrients are recycled Ecosystems

Deficiency disease An illness caused by too little of one vitamin or mineral Food and digestion

Density The mass of one cubic centimetre of a substance Particles and states of matter

Density How much mass is packed into each cubic centimetre Pressure, moments and stretching

Depressant A drug that slows down the nervous system Drugs and health

Diaphragm A sheet of muscle underneath the lungs Breathing and gas exchange

Dietary fibre Parts of plants that cannot be digested Food and digestion

Diffusion Particles spreading from high to low concentration Cells

Diffusion Particles spreading from a high concentration to a low concentration Breathing and gas exchange

Diffusion Particles spreading out from where there are many to where there are few Particles and states of matter

Digestion Breaking large food molecules into small ones Food and digestion

Directly proportional Doubling one quantity doubles the other: the graph is a straight line through the origin Pressure, moments and stretching

Discontinuous variation Falls into separate groups, such as blood group Genetics and evolution

Dispersion The splitting of white light into its colours Light

Displacement A more reactive metal takes the place of a less reactive one in a compound Metals and reactivity

Dissipated Spread out wastefully into the surroundings Energy

Distance How far something has moved Speed and motion

Distance-time graph Shows how far something has travelled at each moment of a journey Speed and motion

Distillation Evaporating a liquid and then condensing it Separating mixtures

DNA The chemical that holds genetic information Genetics and evolution

Double helix The shape of DNA: two strands twisted together Genetics and evolution

Drug A substance that changes the way the body or mind works Drugs and health

Drug misuse Taking a drug in a way that does harm or breaks the law Drugs and health

Ductile Can be pulled out into a wire The periodic table

E

Ear drum A thin skin in the ear that vibrates when sound reaches it Sound

Echo A sound reflected back from a surface Sound

Ecosystem The living things in an area and their non-living environment Ecosystems

Elastic store Filled when a material is stretched or squashed Energy

Electric field The space where a charged object feels a force Electricity

Electrolysis Using electricity to split a compound into its elements Metals and reactivity

Electromagnet A magnet that is turned on and off by the current through it Magnets and electromagnets

Electron A tiny particle with a negative charge Electricity

Element A substance made of only one type of atom Elements, atoms and compounds

Embryo The ball of cells that grows from a fertilised egg Human reproduction

Embryo The young plant inside a seed Plant reproduction

Endothermic Takes in energy, so the surroundings get colder Chemical reactions

Environmental variation Differences caused by surroundings and way of life Genetics and evolution

Enzyme A substance that speeds up the chemical reactions of digestion Food and digestion

Equilibrium When the forces on an object are balanced Forces

Erosion The movement of pieces of rock by water, ice or wind Earth and atmosphere

Ethanol The alcohol made in fermentation Respiration

Evaporating A liquid turning into a gas at its surface, at any temperature Particles and states of matter

Evaporation A liquid turning into a gas Separating mixtures

Evaporation A liquid turning into a gas Acids and alkalis

Evolution The change in a species over many generations Genetics and evolution

Exoplanet A planet that orbits a star outside our solar system Gravity and space

Exothermic Gives out energy, so the surroundings get hotter Chemical reactions

Extension How much longer a spring gets when it is stretched Pressure, moments and stretching

Extinct No individuals of the species are left alive Genetics and evolution

Extraction Separating a metal from its compound Metals and reactivity

F

Femur The thigh bone, the longest bone in the body Skeleton and muscles

Fermentation Anaerobic respiration in yeast Respiration

Fertilisation The nucleus of a sperm joining with the nucleus of an egg Human reproduction

Fertilisation The joining of a male nucleus and a female nucleus Plant reproduction

Field lines Lines with arrows that show the direction and strength of a magnetic field Magnets and electromagnets

Filament The stalk that holds up the anther Plant reproduction

Filter A coloured sheet that lets its own colour of light through Light

Filtrate The liquid that passes through the filter paper Separating mixtures

Filtration Separates an insoluble solid from a liquid Separating mixtures

Fire triangle Fuel, oxygen and heat: the three things a fire needs Chemical reactions

Flagellum Whip-like tail for swimming Cells

Fluid A liquid or a gas Pressure, moments and stretching

Foetus The developing baby, from about eight weeks until birth Human reproduction

Food chain Shows what eats what, in one line that starts with a producer Ecosystems

Food web Food chains from one ecosystem joined together Ecosystems

Force A push or a pull Forces

Fossil fuel Coal, oil or natural gas, formed from the remains of dead organisms Earth and atmosphere

Fossil fuel Coal, crude oil or natural gas Energy

Freezing Changing from a liquid to a solid Particles and states of matter

Frequency The number of waves each second, in hertz (Hz) Sound

Friction Opposes sliding between two surfaces Forces

Fruit What the ovary becomes after fertilisation Plant reproduction

Fuel A substance that stores energy and is burned to release it Chemical reactions

G

Galaxy A huge collection of stars, gas and dust, held together by gravity Gravity and space

Gamete A sex cell: a sperm or an egg Human reproduction

Gamete A sex cell: an egg or a sperm Genetics and evolution

Gas Spreads out to fill its container, and can be squashed Particles and states of matter

Gas exchange Taking in one gas and giving out another Breathing and gas exchange

Gas pressure Caused by gas particles hitting the walls of their container Particles and states of matter

Gene A section of DNA that controls an inherited feature Genetics and evolution

Gene bank A store of seeds, cells or other genetic material Genetics and evolution

Gestation The nine months when the baby develops in the uterus Human reproduction

Global warming The gradual rise in the average surface temperature of the Earth Earth and atmosphere

Glucose The sugar that cells break down in respiration Respiration

Glucose The sugar made in photosynthesis: a plant’s food Photosynthesis

Gradient How steep a line on a graph is Speed and motion

Gravitational field strength The force of gravity on each kilogram, in N/kg Gravity and space

Gravitational potential store Filled when an object is raised Energy

Gravity A force that pulls any two objects towards each other Gravity and space

Greenhouse gas A gas that stops some energy escaping from the Earth to space Earth and atmosphere

Group A column of the periodic table The periodic table

Guard cells The pair of cells that open and close a stoma Photosynthesis

Gut bacteria Microorganisms that live in the intestine and help to break down food Food and digestion

H

Habitat The place where a living thing lives Ecosystems

Halogens The reactive non-metals in Group 7 The periodic table

Hearing range The lowest and highest frequencies an animal can hear Sound

Herbivore An animal that eats only plants Ecosystems

Heredity The passing of genetic information from one generation to the next Genetics and evolution

Hinge joint A joint that bends and straightens, like the elbow Skeleton and muscles

Hooke’s law The extension of a spring is proportional to the force on it Pressure, moments and stretching

Hydrocarbon A compound of hydrogen and carbon only, such as methane Chemical reactions

Hydrogen Gas made when a metal reacts with an acid Acids and alkalis

Hydrogen The gas made when a metal reacts with water or an acid Metals and reactivity

I

Igneous rock Formed when magma cools and turns solid Earth and atmosphere

Implantation The embryo settling into the lining of the uterus Human reproduction

Incident ray The ray that travels towards a surface Light

Indicator Changes colour in acids and alkalis Acids and alkalis

Inert Unreactive: it hardly ever takes part in a reaction The periodic table

Inherited variation Differences passed on from parents in their genes Genetics and evolution

Insoluble Not able to dissolve Separating mixtures

Insulator Does not let current flow through it easily Electricity

Intercostal muscles The muscles between the ribs Breathing and gas exchange

Interdependence Living things in a food web relying on each other Ecosystems

Iodine solution Turns blue-black when starch is there Photosynthesis

Iron sulfide The compound made when iron and sulfur react Elements, atoms and compounds

J

Joint A place where bones meet Skeleton and muscles

Joule The unit of work and of energy Pressure, moments and stretching

Joule The unit of energy Energy

K

Kilojoule The unit of energy on a food label Food and digestion

Kilometres per hour A unit of speed: the kilometres travelled each hour (km/h) Speed and motion

Kilowatt hour The energy a 1 kW appliance transfers in one hour Energy

Kinetic store Filled when an object speeds up Energy

L

Lactic acid The product of anaerobic respiration in muscles Respiration

Large intestine Where water is absorbed and faeces are formed Food and digestion

Lever A rigid bar that turns about a pivot Pressure, moments and stretching

Ligament Joins bone to bone at a joint Skeleton and muscles

Light year The distance that light travels in one year Gravity and space

Like poles Two poles of the same kind, which repel Magnets and electromagnets

Limewater A clear solution that carbon dioxide turns cloudy Chemical reactions

Limit of proportionality The point past which a spring no longer follows Hooke’s law Pressure, moments and stretching

Lipid A fat or an oil, which the body can store for energy Food and digestion

Liquid Flows and takes the shape of its container, but has a fixed volume Particles and states of matter

Litmus Red in acid, blue in alkali Acids and alkalis

Liver The organ that breaks down alcohol Drugs and health

Longitudinal wave Its vibration is along the same line as the wave travels Sound

Loudspeaker Turns an electrical signal into a sound wave Sound

Lubricant A substance, such as oil, that reduces friction Forces

Lung volume A measure of the amount of air breathed in or out Breathing and gas exchange

M

Machine Something that makes work easier, such as a lever or a ramp Pressure, moments and stretching

Magma Molten rock below the surface of the Earth Earth and atmosphere

Magnesium The mineral a plant needs to make chlorophyll Photosynthesis

Magnetic field The space around a magnet where its magnetic force acts Magnets and electromagnets

Magnetic force A non-contact force from a magnet on a magnetic material Magnets and electromagnets

Magnetic material A material that a magnet attracts, such as iron, steel, nickel or cobalt Magnets and electromagnets

Malleable Can be hammered into shape without breaking The periodic table

Mantle The thick layer of hot rock under the crust Earth and atmosphere

Mass The amount of matter in an object, measured in kilograms Gravity and space

Medicine A drug that treats an illness or eases its symptoms Drugs and health

Melting Changing from a solid to a liquid Particles and states of matter

Melting point The temperature at which a solid melts Particles and states of matter

Menstrual cycle A 28-day cycle that prepares the uterus for pregnancy Human reproduction

Menstruation The loss of the lining of the uterus, also called a period Human reproduction

Metal An element that is usually shiny and a good conductor The periodic table

Metamorphic rock Formed when heat and pressure change an existing rock without melting it Earth and atmosphere

Metres per second The unit of speed used most in science (m/s) Speed and motion

Microorganism A living thing too small to see without a microscope Respiration

Microphone Turns a sound wave into an electrical signal Sound

Miles per hour The unit of speed on road signs in the UK (mph) Speed and motion

Milky Way The galaxy that our solar system is in Gravity and space

Minerals Needed in small amounts: iron and calcium are two of them Food and digestion

Mitochondria Release energy by respiration Cells

Mitochondria The parts of a cell where aerobic respiration happens Respiration

Mixture Two or more substances mixed together, not joined Elements, atoms and compounds

Mixture Two or more substances mixed together, not joined Separating mixtures

Molecule A group of two or more atoms joined together Elements, atoms and compounds

Moment The turning effect of a force Pressure, moments and stretching

Motor A machine in which a coil with a current in it spins between the poles of a magnet Magnets and electromagnets

Multicellular Made of many cells Cells

Mutation A change in the DNA Genetics and evolution

N

Natural resource A material from the Earth that we use to make things Earth and atmosphere

Natural satellite A moon: a body, not made by people, that orbits a planet Gravity and space

Natural selection The best-suited individuals survive, breed and pass on their genes Genetics and evolution

Nervous system The brain, the spinal cord and the nerves Drugs and health

Neutral pH 7, neither acid nor alkali Acids and alkalis

Neutralisation An acid and an alkali cancelling out Acids and alkalis

Newton The unit of force Forces

Newton meter Measures the size of a force Forces

Newton metre The unit of a moment (N m) Pressure, moments and stretching

Newton per square metre The unit of pressure (N/m²) Pressure, moments and stretching

Nicotine The addictive drug in tobacco smoke Breathing and gas exchange

Nicotine The addictive drug in tobacco smoke Drugs and health

Nitrates Minerals a plant needs to make proteins for growth Photosynthesis

Noble gases The unreactive gases in Group 0 The periodic table

Non-contact force Acts without the objects touching Forces

Non-metal An element that is usually dull and a poor conductor The periodic table

Normal A line at 90° to a surface, from which angles are measured Light

North pole The end of a magnet that points north when the magnet can turn freely Magnets and electromagnets

Nucleus Controls the cell Cells

O

Obesity Having so much stored body fat that it can harm health Food and digestion

Observer The person who watches and measures Speed and motion

Ohm The unit of resistance Electricity

Opaque Lets no light through Light

Orbit The path of a planet, moon or satellite around a larger body Gravity and space

Ore A rock with enough metal compound in it to be worth extracting the metal Metals and reactivity

Organ Different tissues working together Cells

Oscilloscope Shows a sound as a wave on a screen Sound

Ovary An organ that contains eggs and releases them Human reproduction

Ovary Holds the ovules, and becomes the fruit Plant reproduction

Oviduct The tube from an ovary to the uterus, where fertilisation happens Human reproduction

Ovulation The release of an egg from an ovary Human reproduction

Ovule Contains a female sex cell. If it is fertilised, it becomes a seed Plant reproduction

Oxidation A reaction in which a substance combines with oxygen Metals and reactivity

Oxide A compound of an element with oxygen Elements, atoms and compounds

Oxide A compound of an element joined with oxygen Chemical reactions

Oxide A compound of an element with oxygen Metals and reactivity

Oxygen The gas that aerobic respiration uses up Respiration

Oxygen The gas given out in photosynthesis Photosynthesis

Oxygen debt The extra oxygen needed after hard exercise to break down lactic acid Respiration

P

Painkiller A medicine that eases pain Drugs and health

Palisade cell A tall leaf cell packed with chloroplasts Photosynthesis

Parallel circuit A circuit with more than one branch Electricity

Particle A tiny piece of matter, far too small to see Particles and states of matter

Particle diagram A drawing that shows each atom as a circle Elements, atoms and compounds

Particle model The idea that everything is made of tiny moving particles Particles and states of matter

Pelvis The hip bones, which join the legs to the spine Skeleton and muscles

Penis Carries sperm out of the male’s body Human reproduction

Period A row of the periodic table The periodic table

Periodic table The chart that lists all the elements Elements, atoms and compounds

Periodic table A chart of all the elements, arranged in rows and columns The periodic table

Permanent magnet An object that is magnetic all the time Magnets and electromagnets

Petal Often bright and scented, to attract insects Plant reproduction

pH scale Runs from 0 to 14 Acids and alkalis

Photosynthesis How plants and algae make glucose, using energy from light Photosynthesis

Physical change A change in which no new substance is made Chemical reactions

Physical property A feature you can observe without changing the substance The periodic table

Pitch How high or low a sound is Sound

Pivot The point that a lever turns about Pressure, moments and stretching

Placenta Organ where substances pass between mother and foetus Human reproduction

Planet A large ball of rock or gas that orbits a star Gravity and space

Plotting compass A small compass used to find the direction of a magnetic field Magnets and electromagnets

Pollen Grains that contain the male sex cells Plant reproduction

Pollen tube Grows from a pollen grain down the style to an ovule Plant reproduction

Pollination The transfer of pollen from an anther to a stigma Plant reproduction

Polymer A material made of very long chain molecules Metals and reactivity

Population All the living things of one species in an area Ecosystems

Potential difference The push that makes charge flow Electricity

Power How quickly energy is transferred, in watts Energy

Predator An animal that hunts and eats other animals Ecosystems

Pressure The force on each unit of area Pressure, moments and stretching

Prey An animal that is hunted and eaten Ecosystems

Primary consumer The first consumer in a chain: it eats the producer Ecosystems

Producer A living thing that makes its own food, at the start of a food chain Photosynthesis

Producer A green plant or alga that makes its own food Ecosystems

Product A substance that is made in a chemical reaction Respiration

Product A substance that is made in a chemical reaction Photosynthesis

Product A new substance made in a reaction Chemical reactions

Property What a substance is like, such as its colour or whether it is magnetic Elements, atoms and compounds

Protein The nutrient used to build new tissue for growth and repair Food and digestion

Pure substance A single element or a single compound, with nothing mixed in Elements, atoms and compounds

Pure substance Made of only one substance Separating mixtures

R

Radiation Energy transferred by waves, even across empty space Energy

Ray A straight line with an arrow that shows the path of light Light

Reactant A substance that is used up in a chemical reaction Respiration

Reactant A substance that is used up in a chemical reaction Photosynthesis

Reactant A substance you start with in a reaction Chemical reactions

Reaction time The time taken to respond to something you see, hear or feel Drugs and health

Reactive Takes part in chemical reactions easily The periodic table

Reactivity How readily a substance reacts Metals and reactivity

Reactivity series A list of metals in order of how reactive they are Metals and reactivity

Recreational drug A drug taken for its effect, not for a medical reason Drugs and health

Recycling Processing a used material so that it can be used again Earth and atmosphere

Reduction A reaction in which a substance loses oxygen Metals and reactivity

Reflected ray The ray that leaves a surface after bouncing off it Light

Reflection When light bounces off a surface Light

Refraction A change in the direction of light as it enters a new material Light

Relative motion How something seems to move to an observer who is moving too Speed and motion

Relative speed The speed of one object measured from another object Speed and motion

Relax When a muscle stops pulling Skeleton and muscles

Renewable A resource that is replaced, so it will not run out Energy

Repel Push away from each other Magnets and electromagnets

Residue The solid left in the filter paper Separating mixtures

Resistance How hard it is for current to flow Electricity

Respiration A chemical reaction in cells that releases energy Breathing and gas exchange

Respiration A chemical reaction in cells that releases energy from glucose Respiration

Resultant force The single force left when forces are combined Forces

Retina The layer at the back of the eye that detects light Light

Ribs The bones that protect the heart and lungs Skeleton and muscles

Ribs Bones that make a cage around the lungs Breathing and gas exchange

Rock cycle The processes that change rocks from one type to another Earth and atmosphere

Root hair cell A root cell with a large surface area for taking in water Photosynthesis

Rusting The slow reaction of iron with oxygen and water Metals and reactivity

S

Salt Made when an acid is neutralised Acids and alkalis

Salt The compound made, with hydrogen, when a metal reacts with an acid Metals and reactivity

Saturated solution A solution that can dissolve no more solute Separating mixtures

Scattering When a surface or a material sends light off in all directions Light

Secondary consumer The second consumer in a chain: it eats the primary consumer Ecosystems

Sediment Small pieces of rock that settle in layers Earth and atmosphere

Sedimentary rock Formed from layers of sediment squashed and stuck together Earth and atmosphere

Seed Contains the embryo of a new plant and a food store Plant reproduction

Seed dispersal The spreading of seeds away from the parent plant Plant reproduction

Sepal Protects the flower while it is a bud Plant reproduction

Series circuit A circuit with only one loop Electricity

Skeleton All the bones of the body, joined together Skeleton and muscles

Skull The bones of the head, which protect the brain Skeleton and muscles

Small intestine Where digestion is completed and food is absorbed into the blood Food and digestion

Sodium chloride The compound in table salt Elements, atoms and compounds

Sodium chloride Common table salt Acids and alkalis

Solar system The Sun and everything that orbits it Gravity and space

Solenoid Wire wound into a tight coil Magnets and electromagnets

Solid Has a fixed shape and a fixed volume Particles and states of matter

Solubility How much solute will dissolve in a set amount of solvent Separating mixtures

Soluble Able to dissolve Separating mixtures

Solute The substance that dissolves Separating mixtures

Solution A solute dissolved in a solvent Separating mixtures

Solvent The liquid that does the dissolving Separating mixtures

South pole The end of a magnet that points south when the magnet can turn freely Magnets and electromagnets

Specialised cell Cell with special features for one job Cells

Species A group of living things that can breed together to produce fertile offspring Genetics and evolution

Spectrum The band of colours made when white light is split up Light

Speed How far something travels in a certain time Speed and motion

Spine The backbone, a column of small bones Skeleton and muscles

Stain Dye that makes cell parts show up Cells

Stamen The male part of a flower: an anther on a filament Plant reproduction

Star A huge ball of hot gas that gives out its own light Gravity and space

Starch A store of glucose in a plant Photosynthesis

Starvation Taking in far too little energy for a long time Food and digestion

Static electricity Charge that builds up on an object Electricity

Stationary Not moving Speed and motion

Steady speed A speed that stays the same Speed and motion

Stigma The sticky tip where pollen lands Plant reproduction

Stimulant A drug that speeds up the nervous system Drugs and health

Stomach A bag where food is mixed with acidic juices Food and digestion

Stomata Tiny pores in a leaf that let gases in and out Breathing and gas exchange

Stomata Tiny pores in a leaf that let gases in and out Photosynthesis

Stopwatch An instrument that measures a time Speed and motion

Streamlined Shaped to cut down drag Forces

Style The stalk that joins the stigma to the ovary Plant reproduction

Subliming Changing from a solid straight to a gas Particles and states of matter

Suspension Bits of insoluble solid hanging in a liquid Separating mixtures

T

Tape measure An instrument that measures a distance Speed and motion

Tar The sticky substance in tobacco smoke that causes cancer Breathing and gas exchange

Temperature How hot something is, in degrees Celsius Energy

Tendon Joins a muscle to a bone Skeleton and muscles

Tension The pulling force in a rope or string Forces

Testes The organs where sperm are made Human reproduction

Thermal decomposition When heat breaks one substance down into simpler ones Chemical reactions

Thermal equilibrium When two objects are at the same temperature Energy

Thermal insulator A material that lets energy through only slowly Energy

Thermal store Filled when an object is warmed up Energy

Time How long something takes Speed and motion

Tissue Similar cells working together Cells

Trachea The windpipe: carries air from the nose and mouth towards the lungs Breathing and gas exchange

Translucent Lets some light through, but not a clear view Light

Transparent Lets light through, so you can see clearly through it Light

Transverse wave Its vibration is at right angles to the way the wave travels Sound

Trend A pattern in a property as you go down a group or across a period The periodic table

Triceps The muscle that straightens the arm Skeleton and muscles

U

Ultrasound Sound with a frequency too high for humans to hear Sound

Umbilical cord Joins the foetus to the placenta Human reproduction

Unbalanced forces Forces that do not cancel out Forces

Unicellular Made of one cell Cells

Universal indicator Shows a range of colours for pH Acids and alkalis

Universe Everything that exists, including all the galaxies Gravity and space

Unlike poles Two different poles, which attract Magnets and electromagnets

Unreactive Hardly ever takes part in chemical reactions Metals and reactivity

Upthrust Upward push from a liquid or a gas Forces

Upthrust The upward push of a liquid or a gas on an object in it Pressure, moments and stretching

Uterus The organ where a baby develops, also called the womb Human reproduction

V

Vacuole Bag of cell sap Cells

Vacuum A space with no particles in it Particles and states of matter

Vacuum A space with no particles in it Sound

Vagina Receives sperm, and is the way out for a baby at birth Human reproduction

Variation The differences between living things Genetics and evolution

Vibration A back and forth movement that repeats Sound

Villi Tiny finger-shaped bumps that line the small intestine Food and digestion

Vitamins Needed in small amounts, and named with letters such as A, C and D Food and digestion

Volt The unit of potential difference Electricity

Voltmeter Measures potential difference Electricity

Volume How loud or quiet a sound is, in decibels (dB) Sound

W

Water resistance Drag from moving through water Forces

Wave A vibration that carries energy from place to place, but not matter Sound

Wavelength The distance from one peak of a wave to the next Sound

Weathering The wearing down of rock by physical, chemical or biological processes Earth and atmosphere

Weight The pull of gravity on an object Forces

Weight The force of gravity on an object, measured in newtons Gravity and space

Withdrawal symptoms Unpleasant effects felt when an addicted person stops taking a drug Drugs and health

Word equation Shows the reactants and products of a reaction in words Respiration

Word equation Shows a reaction using the names of the substances Chemical reactions

Work done The energy transferred when a force moves an object Pressure, moments and stretching

X

Xylem Tubes that carry water up from the roots Photosynthesis

Y

Year The time the Earth takes to orbit the Sun once Gravity and space

Yeast A fungus made of single cells, used to make bread and beer Respiration