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Key terms and Spelling List - Year 8 Science
  • Organisms
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    EnzymesSubstances that speed up the chemical reactions of digestion. 
    Dietary fibreParts of plants that cannot be digested, which helps the body eliminate waste. 
    Lipids(fats and oils) A source of energy. Found in butter, milk, eggs, nuts. Protein: Nutrient your body uses to build new tissue for growth and repair. Sources are meat, fish, eggs, dairy products, beans, nuts and seeds.  
    StomachA sac where food is mixed with acidic juices to start the digestion of protein and kill microorganisms. 
    Small intestineUpper part of the intestine where digestion is completed and nutrients are absorbed by the blood. 
    Large intestineLower part of the intestine from which water is absorbed and where faeces are formed. 
    Gut bacteriaMicroorganisms that naturally live in the intestine and help food break down. 
    BreathingThe movement of air in and out of the lungs. 
    Trachea (windpipe)Carries air from the mouth and nose to the lungs. 
    BronchiTwo tubes which carry air to the lungs. 
    BronchiolesSmall tubes in the lung. 
    AlveoliSmall air sacs found at the end of each bronchiole. 
    RibsBones which surround the lungs to form the ribcage. 
    DiaphragmA sheet of muscle found underneath the lungs. 
    Lung volumeMeasure of the amount of air breathed in or out. 
  • Matter
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    ElementsWhat all substances are made up of, and which contain only one type of atom. 
    AtomThe smallest particle of an element that can exist. 
    MoleculesTwo to thousands of atoms joined together. Most non-metals exist either as small or giant molecules. 
    CompoundPure substances made up of two or more elements strongly joined together. 
    Chemical formulaShows the elements present in a compound and their relative proportions. 
    PolymerA molecule made of thousands of smaller molecules in a repeating pattern. Plastics are man-made polymers, starch is a natural polymer. 
    Periodic tableShows all the elements arranged in rows and columns. 
    Physical propertiesFeatures of a substance that can be observed without changing the substance itself. 
    Chemical propertiesFeatures of the way a substance reacts with other substances. 
    GroupsColumns of the Periodic table. 
    PeriodsRows of the Periodic table. 
  • Reactions
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    FuelStores energy in a chemical store which it can release as heat. 
    Chemical reactionA change in which a new substance is formed. 
    Physical changeOne that changes the physical properties of a substance, but no new substance is formed. 
    ReactantsSubstances that react together, shown before the arrow in an equation. 
    ProductsSubstances formed in a chemical reaction, shown after the reaction arrow in an equation. 
    ConservedWhen the quantity of something does not change after a process takes place. 
    CatalystsSubstances that speed up chemical reactions but are unchanged at the end. 
    Exothermic reactionOne in which energy is given out, usually as heat or light. 
    Endothermic reactionOne in which energy is taken in, usually as heat. 
    Chemical bondForce that holds atoms together in molecules. 
  • Forces
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    FluidA substance with no fixed shape, a gas or a liquid. 
    PressureThe ratio of force to surface area, in N/m2, and it causes stresses in solids. 
    UpthrustThe upward force that a liquid or gas exerts on a body floating in it. 
    Atmospheric pressureThe pressure caused by the weight of the air above a surface. 
    EquilibriumState of an object when opposing forces are balanced. 
    DeformationChanging shape due to a force. 
    Linear relationshipWhen two variables are graphed and show a straight line which goes through the origin, and they can be called proportional. 
    NewtonUnit for measuring forces (N). 
    Resultant forceSingle force which can replace all the forces acting on an object and have the same effect. 
    FrictionForce opposing motion which is caused by the interaction of surfaces moving over one another. It is called 'drag' if one is a fluid. 
    TensionForce extending or pulling apart. 
    CompressionForce squashing or pushing together. 
    Contact forceOne that acts by direct contact. 
  • Genes
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    SpeciesA group of living things that have more in common with each other than with other groups. 
    VariationThe differences within and between species. 
    Continuous variationWhere differences between living things can have any numerical value. 
    Discontinuous variationWhere differences between living things can only be grouped into categories. 
    PopulationGroup of organisms of the same kind living in the same place 
    Natural selectionProcess by which species change over time in response to environmental changes and competition for resources. 
    ExtinctWhen no more individuals of a species remain. 
    BiodiversityThe variety of living things. It is measured as the differences between individuals of the same species, or the number of different species in an ecosystem. 
    CompetitionWhen two or more living things struggle against each other to get the same resource. 
    EvolutionTheory that the animal and plant species living today descended from species that existed in the past. 
  • Energy
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    Thermal conductorMaterial that allows heat to move quickly through it. 
    Thermal insulatorMaterial that only allows heat to travel slowly through it. 
    TemperatureA measure of the motion and energy of the particles. 
    Thermal energyThe quantity of energy stored in a substance due to the vibration of its particles. 
    ConductionTransfer of thermal energy by the vibration of particles. 
    ConvectionTransfer of thermal energy when particles in a heated fluid rise. 
    RadiationTransfer of thermal energy as a wave. 
    WorkThe transfer of energy when a force moves an object, in joules. 
    LeverA type of machine which is a rigid bar that pivots about a point. 
    Input forceThe force you apply to a machine. 
    Output forceThe force that is applied to the object moved by the machine. 
    DisplacementThe distance an object moves from its original position. 
    DeformationWhen an elastic object is stretched or squashed, which requires work. 
  • Electromagnets
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    Magnetic forceNon-contact force from a magnet on a magnetic material. 
    Permanent magnetAn object that is magnetic all of the time. 
    Magnetic polesThe ends of a magnetic field, called north-seeking (N) and south-seeking poles (S). 
    ElectromagnetA non-permanent magnet turned on and off by controlling the current through it. 
    SolenoidWire wound into a tight coil, part of an electromagnet. 
    CoreSoft iron metal which the solenoid is wrapped around. 
  • Earth
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    Global warmingThe gradual increase in surface temperature of the Earth. 
    Fossil fuelsRemains of dead organisms that are burned as fuels, releasing carbon dioxide. 
    Carbon sinkAreas of vegetation, the ocean or the soil, which absorb and store carbon. 
    Greenhouse effectWhen energy from the sun is transferred to the thermal energy store of gases in Earth's atmosphere. 
    Natural resourcesMaterials from the Earth which act as raw materials for making a variety of products. 
    MineralNaturally occurring metal or metal compound. 
    OreNaturally occurring rock containing sufficient minerals for extraction. 
    ExtractionSeparation of a metal from a metal compound. 
    RecyclingProcessing a material so that it can be used again. 
    ElectrolysisUsing electricity to split up a compound into its elements. 
  • Waves
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    UltrasoundSound waves with frequencies higher than the human auditory range. 
    Ultraviolet (UV)Waves with frequencies higher than light, which human eyes cannot detect. 
    MicrophoneTurns the pressure wave of sound hitting it into an electrical signal. 
    LoudspeakerTurns an electrical signal into a pressure wave of sound. 
    Pressure waveAn example is sound, which has repeating patterns of high-pressure and low-pressure regions. 
    WavesVibrations that transport energy from place to place without transporting matter. 
    Transverse waveWhere the direction of vibration is perpendicular to that of the wave. 
    TransmissionWhere waves travel through a medium rather than being absorbed or reflected. 
  • Ecosystem
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    Aerobic respirationBreaking down glucose with oxygen to release energy and producing carbon dioxide and water. 
    Anaerobic respiration (fermentaReleasing energy from the breakdown of glucose without oxygen, producing lactic acid (in animals) and ethanol and carbon dioxide (in plants and microorganisms). 
    FertilisersChemicals containing minerals that plants need to build new tissues. 
    PhotosynthesisA process where plants and algae turn carbon dioxide and water into glucose and release oxygen. 
    ChlorophyllGreen pigment in plants and algae which absorbs light energy. 
    StomataPores in the bottom of a leaf which open and close to let gases in and out. 
  • Working Scientifically