This document defines terms related to cells and the growing plant. It provides definitions for terms like bacteria, cell, chloroplast, diffusion, epidermal tissue, fungi, greenhouse, leaf, limiting factor, photosynthesis, stomata, tissue, and xylem. It describes the structures and functions of plant and bacterial cells, plant tissues and organs, and some of the key processes involved in plant growth like photosynthesis and diffusion.

1. B2a – Cells and the Growing Plant
Term Definition Image
Bacteria Single-celledmicroorganism, 1-5μm inlength(very
small). The DNA isnot enclosedinanucleus.
Bacterial cellshave cytoplasm, acell membrane,and
a cell wall.
Cell Buildingblock of livingthings.
Cell Membrane A thinlayerarounda cell that controlsthe movement
of substancesintoandoutof the cell.
Cell Wall Rigidcellulose layeroutside the cellmembraneina
plantor bacterial cell.
Chlorophyll Greensubstance foundinchloroplasts,where light
energyistrappedforphotosynthesis.
Chloroplast Small discinthe cytoplasmof plantcells,containing
chlorophyll. Photosynthesisoccursinthe
chloroplasts.
Community All the populationsof organismsthat live together
and interactinthe same area.
Concentration
Gradient
Difference inconcentrationof asubstance fromone
regiontoanother.
Cytoplasm Jelly-like contentsof acell,inside the cell membrane.
Cellularstructuresare suspendedinthe cytoplasm,
and thisiswhere manyof the cell’sreactionsoccur.
Differentiation Developmentof cellsintotypesthatare specialized
for a particularfunction.
Diffusion The spreadingof the particlesof a gas or a substance
insolution,resultingin anetmovementfroma
regionof highconcentrationtoa regionof lower
concentration. The biggerthe difference in
concentration,the fasterthe diffusionhappens.
Digestive System Organ systemthatdigestfoodintosmallerparticles
and absorbs these intothe body.

2. Distribution Detail of where speciesare foundoverthe total area
where theyoccur. For example,woodlicemayhave
a highdistributionoveralog.
Epidermal Tissue Tissue oncell thickon the surface of plantroots,
stems,and leaves,thatprotectsthe organs.
Fungi Organismswithcellscontainingamembrane,
cytoplasm,nucleus,andacell wall. The fungal cell
wall ismade of chitinratherthancellulose of aplant
cell wall.
Greenhouse Structure where plantscanbe grownunder
controlledconditions.
Leaf Plantorgan specializedforphotosynthesis.
LimitingFactor Factor such as carbon dioxide level,light,or
temperature,whichwill affectthe rate of
photosynthesisif itisshortsupply. Increasingthe
limitingfactorwill increase the rate of
photosynthesis.
Mean Average of a collectionof data.
Median Middle value of a collectionof data.
Microscope Instrumentusedtoview small objects. A light
microscope magnifiesuptoabout1500x; an electron
microscope giveshighermagnifications.
Mode Most popularvalue ina collectionof data.
Multicellular Beingbuiltof manycells,all workingtogetherasan
organism.
Nucleus Structure inside acell thatcontrolsthe cell’s
activities. Itcontainschromosomesmade of DNA.
Organ Collectionof differenttissuesworkingtogetherto
performa functionwithinanorganism;examples
include the stomachinan animal anda leaf ina
plant.

3. Organ System Collectionof differentorgansworking togetherto
performa majorfunctionwithinanorganism;an
example isthe digestivesysteminananimal.
Palisade Layer A layerof tall columnarcellscontainingchloroplasts,
where the majorityof photosynthesisoccursina
leaf.
Palisade Mesophyll
Cells
Tall columnarcellscontainingchloroplasts,where
the major of photosynthesisoccursina leaf.
PermanentVacuole Fluid-filledcavityinaplantcell.
Phloem Planttissue made upof livingcellsthathasthe
functionof transportingfoodsubstancesthroughthe
plant.
Photosynthesis Processbywhichplantsbuildcarbohydratesfrom
carbon dioxide andwaterusingenergyfromsunlight.
Population The numberof organismsof a speciesinagivenarea.
Rate of Photosynthesis How quicklyaplantisphotosynthesizing. The rate is
affectedbyfactorsincludingcarbondioxide level,
light,andtemperature.
Relationship Interactionbetweendifferentspecieslivingtogether
inthe same area,such that one speciesaffects
another. Anexample of thisisa predator-prey
relationship.
Sampling Countinga small numberof a large total population
on orderto studyitsdistribution.
Specialized Specializedcellshave structure wellsuitedtotheir
function.
Stomata Poreson the surface of a leaf thatallowswater,
carbon dioxide,andoxygentomove inandout of the
leaf.
Tissue Group of cellsof similarstructure andfunction
workingtogether,suchasmuscle tissue inananimal
and xyleminaplant.

4. Xylem Planttissue made upof dead cellsthat hasthe
functionof transportingwateranddissolved
substancesthroughthe plant.

5. B2b – Genes and Proteins, Inheritance, Gene Technology, and Speciation
Term Definition Image
Aerobic Using/inthe presence of oxygen.
Allele Versionof agene,suchas blue eyesorbrowneyes.
AminoAcid Moleculescontainingcarbon,hydrogen,nitrogen,
and oxygen. Manyaminoacidsjointogethertomake
a protein.
Amylase Enzyme that catalysesthe breakdownof starchto
sugar molecules.
Anaerobic Withoutusing/notinthe presence of oxygen.
Antibody Special proteininthe bodythatcan bindto a
particularantigenanddestroya particularpathogen.
Asexual Reproduction Reproductionwithoutgametes/sex cells,using
mitosis.
Breathing Movementsof the ribcage and diaphragmthatcause
air to enterandleave the lungs.
Carbohydrase Enzyme that catalysesthe breakdownof large
carbohydrate molecules,suchasstarch,to smaller
sugar molecules.
Catalyst Substance thatspeedsupa reactionwithoutbeing
usedup inthe reaction
Chromosome Structure ina cell nucleusthatconsistsof one
molecule of DNA thathas condensedandcoiledinto
a linearstructure.
Denatured Describesthe state of a proteinwhenitsshape has
alteredanditcan nolongercarry out itsfunction.

6. Detergent Substance addedtowaterto improve itscleaning
properties.
Digestion Breakingdownof large moleculesintosmaller,
soluble particlesthatcanbe absorbed.
Digit Fingeror toe.
Diploid Describesacell that hasa nucleuswithtwosetsof
chromosomes;abodycell.
DNA
(deoxyribonucleicacid)
Chemical thatcarriesthe geneticcode.
DNA Bases Moleculesarrangedinpairswithineachmolecule of
DNA. C pairs withG and A pairs withT.
DNA Fingerprinting Technique thatanalysespartsof the DNA of an
individualandcomparesitwiththatof other
individuals/DNA samplestofindoutwhether
someone committedacrime or establishif
individualsare related.
Dominant Visiblecharacteristicpresentinanorganismeven
whenonlyone alleleof the gene ispresent.
Endangered Describesaspeciesthathas low numbersandisin
dangerof becomingextinct.
Enzyme Biological catalystmade of protein. Enzymes
catalyse chemical reactionsinlivingorganisms.
Evolution Gradual change inan organismovertime.
Extinction End of a species,whenall itsmembershave diedout.
F1 Generation Firstfilial (daughter) generation:the offspringfroma
geneticcrossbetweentwo true-breedingparents.

7. Fatigue Build-upof lacticacidinmusclesthatstopsthem
fromcontracting efficiently.
Fermenter Large containerusedforgrowinglarge numbersof
microorganisms.
Fertilization Fusionof male andfemale gamete nuclei.
Fossil Preservedremainsof ancientlivingthings.
Fructose Type of sugar,whichtastessweeterthanglucose.
Gamete Sex cells. Male gametesare spermandfemale
gametesare eggs. Gameteshave half the normal
numberof chromosomes.
Gene Lengthof DNA that codesfora specific
characteristic/protein.
Glucose Type of sugar.
Glycogen Large insolublecarbohydrate molecule;similarto
starch but foundonlyinanimal cells,some bacterial
cells,andsome fungi.
Growth Increase insize,usuallywithanincrease incell
numbers.
Haploid Describesacell that hasa nucleuswithonlyone set
of chromosomes;asex cell.
Heart Rate Numberof timesperminute aheartheats.
Hormone Chemical made bya glandand carriedinthe bloodto
itstarget organ(s).

8. Inheritance Factor Term usedbyMendel. We know call thisa gene.
Isolation Separationof twopopulationsof aspeciessothat
theycannot interbreed. Forexample,bya
geographical barriersuchas an oceanor mountain
range.
Isomerase Type of enzyme thatrearrangesthe atomsina
molecule.
Lactic Acid Chemical made fromthe incompletebreakdownof
glucose duringanaerobicrespiration.
Lipase Enzyme that catalysesthe breakdownof fats(lipids)
to fattyacids and glycerol.
Meiosis Type of cell divisionthatoccursto formsex cells,
resultinginfourgeneticallydifferentcells.
Mitochondria Structuresinanimal andplant cellswhere aerobic
respirationtakesplace.
Mitosis Type of cell divisionthat occursinbody cells,
resultingintowgeneticallyidentical cells.
Monohybrid
Inheritance
Inheritance patternof asingle characteristic,
determinedbyone gene (thatmayhave twoalleles).
Mucus Slimysubstance made inspecial cells/glands.
Mutation Change inthe structure of a gene. A mutationmay
resultinthe gene codingfora different
protein/characteristic.
Optimum Best.
OxygenDebt Lack of oxygeninmuscle cells. Oxygenisneededto
oxidize lacticacidinthe muscle tocarbon dioxide
and water.

9. Protease Enzyme that catalysesthe breakdownof proteinto
aminoacids.
Protein Large molecule (polymer) made of manyaminoacids
joinedtogether. Proteinshave manyfunctions,
includingstructural (asinmuscle),hormones,
antibodies,andenzymes.
Recessive Visiblecharacteristicthatisonlypresentinan
organismif twoallelesof the same gene are present.
Respiration Processbywhichlivingthingsrelease energyfrom
carbohydrates,alsoproducingcarbondioxideand
water.
Sex Chromosomes Chromosomesinvolvedwithdeterminingthe sex of
an individual. Inhumans,if youhave twoX
chromosomesyouare female,if youhave one X
chromosome andone Y chromosome,youare male.
Speciation Separate evolutionof two populationsof the same
speciestoformtwoseparate species.
Specific Enzymesare specific;theyacton onlyone substrate.
Starch Large insolublecarbohydrate molecule,storedin
plantcells.
StemCell Undifferentiatedcell thatcandivide by mitosisandis
capable of differentiatingintoanyof the cell types
foundinthat organism.
Substrate Substance acteduponby an enzyme inachemical
reaction. The substrate moleculesare changedinto
productmolecules.
Tract A systemof tubesinthe body,such as the digestive
tract or respiratorytract.
Zygote (Usually) diploidcellresultingfromthe fusionof an
eggand a sperm.

10. C2a – Structures, Properties, and Uses
Term Definition Image
Actual Yield Amountof product foundby experiment.
Alkali Metal An elementinGroup1 of the periodictable (lithium,
sodium,potassium, rubidium, caesium, francium).
Alloy Mixture of a metal withone ormore otherelements.
The physical propertiesof analloyare differentfrom
those of the elementsinit.
AtomicNumber The numberof protonsinthe nucleusof an atom.
Buckminsterfullerene Form of carbon consistingof moleculescontaining60
carbon atomsjoinedtogethertoforma hollow
sphere.
Chromatogram The record obtainedin chromatography.
Compound Substance made upof twoor more different
elementschemicallycombined.
CovalentBond Sharedpairof electronthatholdstwoatoms
together.
Delocalized Describeselectronsthatare free to move througha
structure.
Diamond Form of the elementcarboninwhicheachcarbon
atom isjoinedtofourothercarbon atoms bystrong
covalentbonds.
DisplayedFormula Descriptionof acovalentlybondedcompoundof
elementthatusessymbolsforatoms. Italsoshows
the covalentbondsbetweenatoms.
Dot and CrossDiagram Diagram thatshowshow the electronsare arranged
ina molecule orinions.

11. Double CovalentBond Strongbond betweentwoatomsthatconsistsof two
sharedpairsof electrons.
Electrode Conductorthrough whichan electriccurrententers
or leavesameltedordissolvedioniccompoundin
electrolysis.
Electron Sub-atomicparticle foundoutside the nucleusof an
atom.It has a charge of -1 and a verysmall mass
comparedto protonsand neutrons.
Formula Descriptionof acompoundor elementthatuses
symbolsforatoms. It showshow manyatoms of
each type are in the substance.
Fullerene Form of the elementcarbonbasedonhexagonal
ringsof carbon atoms.
Gas Chromatography Methodof separatingand identifyingamixture of
substance,andcomparingthe amountsof the
differentsubstancesinthe mixture. Heliumor
nitrogengascarrieschemicalsfroma sample through
a chromatographycolumn.
Giant Covalent
Structure
Three-dimensional networkof atomsthatare joined
togetherbycovalentbondsina regularpattern.
Giant IonicLattice Regular,three-dimensionalpatternof ionsheld
togetherbystrongelectrostaticforces.
Giant Metallic
Structure
Regular,three-dimensionalpatternof positively
chargedmetal ionsheldtogetherbyasea of
delocalizedelectrons.
Graphite Form of the elementcarboninwhicheachcarbon
atom isjoinedtothree othercarbonatoms bystrong
covalentbondstoforma layerof carbon atoms.
There are manyof these layersinapiece of graphite.
The layersare heldtogetherbydelocalizedelectrons
that move betweenthe layers.

12. Halogen An elementinGroup7 of the periodictable (fluorine,
chlorine,bromine,iodine,astatine).
HighDensity
Poly(ethene)
Form of poly(ethene) whosemoleculesdonot
containside branchessothat theycan pack closely
together. HDPEis rigidandnot transparent.
IntermolecularForces Relativelyweakforcesbetweenamoleculeandits
neighbours.
Ion Atomor group of atoms that have gainedorlost
electronssoithas become electricallycharged.
IonicBonding Strongelectrostaticforce of attractionbetween
oppositelychargedions. Ionicbondsactin all
directions.
IonicCompound Compoundmade upof positively andnegatively
chargedions.
Isotope Atomwiththe same numberof protonsbut a
differentnumberof neutrons.
Low Density
Poly(ethene)
Form of poly(ethene) whosemoleculescontainside
branchesso that theydonot pack closelytogether.
LDPE is flexibleandtransparent.
Lubricant Substance thathelpsmovingpartsslide overeach
othereasily.
Macromolecule Three-dimensional networkof atomsthatare joined
togetherbycovalentbondsina regularpattern.
Mass Number The total numberof protonsand neutronsinthe
nucleusof an atom.
Mass Spectrometer Instrumentthatidentifiessubstancesquicklyand
accuratelyand can give theirrelativemolecular
masses.

13. MaximumTheoretical
Yield
Amountof product,calculatedfromthe reaction
equation,whichwouldbe obtainedif none waslost
whenthe reactionwascarriedout.
Metal Halide A compoundmade upof a metal anda halogen.
MetallicBonding Forcesof attractionbetweenpositivelycharged
metal ionsanddelocalizedelectronsina metal.
Mobile Phase In chromatography,the solventthatcarries
chemicalsfroma sample throughachromatography
columnor alonga piece of chromatographypaper.
Mole The relative formulamassof a substance ingrams.
MolecularFormula Descriptionof acompoundor an elementthatuses
symbolsforatoms. It showsthe relative numberof
atomsof each type inthe substance.
= H2O
MolecularIonPeak Peakon a mass spectrographwhose massrepresents
the relative formulamassof the moleculebeing
analysed.
Molecule Particle made upof twoor more atoms chemically
joinedtogether.
Nanoparticle Tinyparticle made upof onlya few hundredatoms.
It measuresbetween1– 100 nm across.
Nanoscience The study of nanoparticles.
Nanotube Sheetsof carbonatoms arrangedinhexagonsthat
are wrappedaroundeachotherto forma cylinder
witha hollowcore.
Neutron Sub-atomicparticle foundinthe nucleusof anatom.
It has nocharge and a relative massof 1.
Nucleus The relativelyheavycentral partof an atom, made
up of protonsand neutrons.

14. Oxide Ion An atomof oxygenthathasgainedtwoelectronsto
forman ion withtwonegative charges,O2-
.
PaperChromatography Methodof separatingsubstancesinamixture by
allowingasolutionof the mixture toflow alonga
sheetof special paper. If the substancesinthe
mixture travel atdifferentspeeds,theywill be
separated.
Percentage byMass The percentage bymass of an elementina
compoundisequal tothe number of grams of the
elementin100 grams of the compound.
% 𝒎𝒂𝒔𝒔 =
𝒎 𝒆𝒍𝒆𝒎𝒆𝒏𝒕
𝒎 𝒄𝒐𝒎𝒑𝒐𝒖𝒏𝒅
× 𝟏𝟎𝟎
Percentage Yield actual yeild
maximum theoretical yeild
× 100
Proton Sub-atomicparticle foundinthe nucleusof anatom.
It has a charge of +1 and a relative massof one.
Relative AtomicMass The relative atomicmassof an elementcompares
the mass of atoms of the 12
Ccarbon atom. It is
workedoutby addingtogetherall the Ar valuesfor
the atoms inthe formula. Its symbol isMr.
Relative FormulaMass The relative formulamassof a substance isthe mass
of a formulaunitof that substance comparedto
mass of a 12
C carbon atom. It isworkedoutby
addingtogetherall the Ar valuesforthe atoms inthe
formula. Itssymbol isMr.
RetentionTime In chromatography,the time ittakesfora chemical in
a mixture tomove throughthe stationaryphase.
Reversible Reaction Reactioninwhichthe productsof a reactioncan
react to produce the original reactants.
Shape MemoryAlloy Alloythat,whenbentortwisted,keepsitsnew
shape,butwhenheatedwill returntoitsoriginal
shape.
StationaryPhase In chromatography,the mediumthroughwhichthe
mobile phase passes.
Sub-AtomicParticle Describesparticlesfromwhichatomsare made,
includingprotons,neutrons,andelectrons.
ThermosettingPolymer Polymerthatdoesnotmelt.

15. Thermosoftening
Polymer
Polymerthatsoftenseasilyonheatingandthatcan
be mouldedintonew shapes.
Yield Amountof the requiredproduct made ina reaction.

16. C2b – Rates, Energy, Salts, and Electrolysis
Term Definition Image
ActivationEnergy Minimumamountof energythatparticlesneedto
orderto react whentheycollide.
Alkali Soluble base. Soluble hydroxidesneutralizeacids.
Anhydrous Describesasalt thatdoesnot have itswaterof
crystallization.
Base Metal hydroxide oroxide. Basesneutralizeacids.
Bauxite The most commonor of aluminium,containingthe
mineral aluminiumoxide.
Brine Concentratedsodium chloride solution.
Catalyse To speedupa reactionusinga catalyst.
Catalyst Substance thatspeedsupa reactionwithoutbeing
usedup inthe reaction
Collide Particlescollidewhentheycome intocontactasone
or both of them are moving.
Cryolite Substance inwhichaluminaoxide dissolvesinan
aluminiumelectrolysiscell,sothatthe processcan
take place at a lowertemperature thanwouldbe the
case if pure aluminiumoxide wereused.
Crystallization Processbywhichsolidcrystalsare obtainedfrom
solution.
Electrolysis Processbywhichmeltedordissolvedionic
compoundsare brokendownbypassingan electric
currentthrough them.

17. Electrolyte Solutionof anionicsubstance thatisbrokendownin
an electrolysiscell.
Electroplating Coveringanobjectwitha thincoatingof metal
duringan electrolysisreaction. The objecttobe
platedisthe negative electrode inanelectrolysiscell.
EndothermicReaction Reactioninwhichenergyistransferredfromthe
surroundingstoa reactingmixture.
ExothermicReaction Reactioninwhichenergyistransferredtothe
surroundings,inthe formof heat,light,andsound
for example.
Half Equation Equationthat describesthe lossorgainof electrons
by a reactant atomor ion,but isnot balancedin
termsof electrical charge.
Hydrated Describesasalt thatcontainswaterof crystallization
inits structure,suchas CuSO4•5H2O.
HydrogenIon A hydrogenatomthat haslostits electron(basically,
it’sa proton),H+
.
Hydroxide Ion Ionwiththe formulaOH-
. It makessolutionsalkaline.
NeutralizationReaction Reactioninwhichhydrogenionsreactwith
hydroxide ionstoformwater.
Oxidation Processinwhichoxygenisaddedtoan elementor
compound,orby which an atom or ionloses
electrons.
pH Scale Scale that describesthe concentrationof hydrogen
ionsina solution.
Rate of Reaction Amountof product made perunitof time,or,the
amountof reactantconsumedperunitof time.
Reduction Processin whichoxygenisremovedfroma
compound,oran atom or iongains electrons.

18. Salt Compoundthatcontainsmetal ionsandthat can be
made froman acid.
Soluble Substance thatdissolvesinagivensolvent.
Successful Collision Collisionbetween reactantparticlesthatresultsina
reaction.
Surface Area In a chemical reactioninvolvingasolid,the areaof
the solidthatis incontact withthe otherreactants.

19. P2a – Forces and Motion
Term Definition Image
Accelerate To speedup,slow down,orchange direction.
Acceleration Change invelocitypersecond,canbe speedingup,
slowingdown,orchangingdirection. Measuredin
m/s2
.
AirResistance Resistive force thatslowsdownobjectsmoving
throughair.
BrakingDistance Distance movedbya vehicle whenitslowsdownand
stopsafterthe brakeshave beenapplied.
BrakingForce Usedto stop or slowdowna movingobjectsuchas a
car.
Deceleration Negative acceleration,accelerationinthe opposite
directiontothe motion,slowingdown.
DirectlyProportional Describesthe relationshipbetweentwovariables. If
one increase bya factor the otherincreasesbythe
same factor (ie.if one doubles,sodoesthe other).
Distance-Time Graph Graph showingdistance on the y-axisandtime on
the x-axis. Itshowsthe distance travelledfroma
certainpointat a particularmoment.
ElasticPotential Energy Energystoredinstretchedor compressedobjects.
Equal and Opposite Describesthe pairof forcesproducedwhen objects
interact:equal insize andactingin opposite
directions.
Extension Change inlengthof an objectwhena force isapplied.
Fluid A liquidorgas (anythingthatflows).

20. Force Pushor pull that changesthe wayan objectismoving
or its shape. Measuredinnewtons(N).
Friction Force that acts tostop or slow downtwoobjectsthat
are slidingagainsteachother.
Gradient Slope of a graph.
Gravitational Field
Strength
Strengthof the force of gravityon a planet. OnEarth
it isapproximately10 N/kg.
Gravitational Potential
Energy
Energystoredinan objectthat isin a higherposition
than itssurroundings.
Joule A unitformeasuringenergyrepresentedbyJ,the
workdone by a force of one newtonmovingone
metre inthe directionof the force.
KineticEnergy Energydue to the movementof anobject.
Law of Conservationof
Momentum
Law that statesthat momentumisconservedin
collisions. Total momentumof a systembefore a
collisionorexplosionisthe same asthe total
momentumof the systemaftera collisionor
explosion.
Limitof Proportionality Pointbeyondwhichthe extensionof anobjectisno
longerdirectlyproportiontothe force applied.
Mass Amountof matterin an object. Measuredin
kilograms(kg).
Momentum Mass of an objectx velocity.
Newton Unit of force,representedbyN.

21. Pairof Forces Two equal andopposite forcesproducedwhen
objectsinteract.
Power How muchenergya device useseachsecond. Given
inwatts or kilowatts.
ReactionTime Time takenfromseeingahazard to startingto press
the brake pedal.
RegenerativeBraking A type of vehicle thatconvertssome of the kinetic
energyintoa useful formof energy(eg.chemical
energyinthe battery).
Resistive Force Force in the opposite directiontothe directionof
motion.
ResultantForce Single force thatwouldhave the same overall effect
of all the forcesactingon an objectcombined.
Speed Distance travelled inacertaintime. Usually
measuredinm/s.
SpeedCamera Camerausedto findthe speedof a vehicle.
Stationary Notmoving,at rest.
StoppingDistance Sumof the thinkingdistance andbrakingdistance.
Terminal Velocity Maximumvelocityof anobjectwhenthe forcesonit
are balanced. Usuallyappliedtoobjectsfallingunder
gravity.
ThinkingDistance Distance travelledbyavehicle inthe reactiontime.
Velocity How fastsomethingismovinginacertaindirection.

22. Velocity-TimeGraph Graph withvelocityonthe y-axisandtime onthe x-
axis. It showsthe velocityof anobjectat a particular
moment.
Watt A unitusedto measure power. Definedasthe power
of a device thattransfersone joule of energyper
second.
Weight Force on an objectdue to the force of gravityon a
planet.
Work Done Energytransferred,measuredinjoules. Workdone
isequal to the force appliedx distance movedinthe
directionof the force.

23. P2b – Electricity and Radiation
Term Definition Image
Activity Numberof radioactive decayspersecond.
AlternatingCurrent
A. C.
Currentthat continuallyreversesdirection.
AlphaParticle Veryionizing,butnotverypenetratingformof
ionizingneutrons(ahelium nucleus).
AtomicNumber The numberof protonsinthe nucleusof an atom.
Attract Pull towards.
BackgroundRadiation Radiationaroundusall of the time froma varietyof
natural and man-made sources.
Battery Scientificname fortwoor more cellsconnected
together.
Beta Particle Ionizingformof radiation. Itisa fastelectionfrom
the nucleus.
Black Hole A verysmall,dense objectwithgravitysostrongnot
evenlightcanescape. The resultof the supernovaof
a massive star.
Cell A device thattransferschemical energyintoelectrical
energy.
ChainReaction One reactiongoingonto create another,which
createsanother,andso on,such as nuclearfissionis
a chain reactioninside anuclearreactor.
Charge Propertyof some objects(like electronsand
protons). Theycan be positive ornegative.

24. ConventionalCurrent Model usedto representchargesmovingthrougha
circuit. Conventioncurrentgoesfrompositive to
negative (oppositedirectionof electionflow).
Coulomb Unit of electriccharge.
Current Movementof chargedparticles(usuallyelectrons)
througha material.
Current-Potential
Difference Graph
Graph withcurrenton the y-axisandpotential
difference onthe x-axis. Itshowshow the current
variesfordifferentpotential differences.
Diode Circuitcomponentthatconductselectricityinone
directiononly. Ithasa veryhighresistance inthe
reverse direction.
DirectCurrent
D. C.
Currentthat goesinonlyone direction.
Double-Insulated Describesanappliance inwhichall the live
componentsare sealedawayfromthe case,sothey
cannot become live.
Earth Pin/wire thatcarriesenergysafelyawayfromthe
device tothe groundif there isa fault.
Electron Sub-atomicparticle foundoutside the nucleusof an
atom.It has a charge of -1 and a verysmall mass
comparedto protonsand neutrons.
ElectrostaticCharge Charge from electronsthathave beenmovedtoor
froman insulator.
FilamentLamp Lamp containingacoil of wire thatglowswhenan
electriccurrentflowsthroughit.
Frequency Numberof cyclesof potential difference persecond
for an alternatingcurrent. MeasuredinHertz(Hz).

25. Fuse Thinpiece of wire thatmelts(andbreaksthe circuit)
if too much currentflowsthroughit.
Gamma Knife A special machine foundinhospitalsthatuses
gamma rays to kill canceroustumoursbyfocusing
themon the tumourand minimizingthe exposure to
surroundingtissues.
Gamma Ray Verypenetratingbutnotvery ionizingformof
ionizingradiation. Itisa highfrequency
electromagneticwave.
Half-Life The time takenfor half of the radioactive nuclei ina
substance todecay,or the time takenforthe activity
froma substance tohalve.
InsulatingMaterial Doesnot allowelectronstomove easilythroughit.
Ion Atomor group of atoms that have gainedorlost
electronssoithas become electricallycharged.
IonizingRadiation Alpha,beta,andgamma radiationthatremoves
electronsfromthe atomsof the material itpasses
through.
Isotope Atomwiththe same numberof protonsbut a
differentnumberof neutrons.
Light-Dependent
Resistor
Special type of resistorwhose resistance decreases
whenthe intensityof lightfallingonitincreases.
Light-EmittingDiode Diode thatemitslightwhenanelectriccurrentflows
throughit.
Live Pin/wire thattransfersenergytoanappliance.
Mass Number The total numberof protonsand neutronsinthe
nucleusof an atom.

26. Nebula Huge cloudof gas and dustin space (mainly
hydrogen).
Neutral Pin/wire thatcompletesthe circuit.
Neutron Sub-atomicparticle foundinthe nucleusof anatom.
It has nocharge and a relative massof 1.
NeutronStar A small,dense objectthatremainsaftera supernova.
NuclearFission Splittingof alarge nucleuswhenitabsorbsa
neutron,intotwoor more smallernuclei.
NuclearFusion Fusingtwoatomsto form a single,largernucleus,
releasingenergy.
Nucleus The relativelyheavycentral partof an atom, made
up of protonsand neutrons.
Oscilloscope Device thatcan be usedtodetermine the frequency
and potential differenceof anA.C.supply.
Parallel Circuit Circuitwithcomponentsconnectedside byside so
that there ismore than one path to take aroundthe
circuit.
Plutonium239 Isotope of plutoniumthatcanbe usedto generate
heatin nuclearpowerstations.
Potential Difference Difference involtagebetweentwopointsinacircuit.
Measuredinvolts(V). Alsoameasure of the
difference Ienergycarriedbythe electronsbetween
these twopoints.
Proton Sub-atomicparticle foundinthe nucleusof anatom.
It has a charge of +1 and a relative massof one.
Protostar Ball of hot,dense gason itsway to becomingastar.

27. Radioactive Decay Breakdownof an unstable nucleus,givingoutalpha
particles,betaparticles,orgammarays.
Random Havingno setpatternin whichatomswill decay.
RedGiant The resultwhena smallerstarbeginstodie. It
expandsandcools, formingared giant.
RedSuperGiant Whena large star beginstodie,itexpandsandcools,
forminga giganticredsupergiant.
Repel Pushaway.
Residual Current
CircuitBreaker
Circuitbreakerthatdetectsa difference incurrent
betweenthe liveandneutral wire.
Resistance Measure of howdifficultitisforelectronstopass
througha component. Measuredinohms(Ω).
Resistor Circuitcomponentthatreducesthe currentflowing
ina circuit.
Series Circuitwithcomponentsthatare connectedendto
endso that there isonlyone wayaroundthe circuit.
StaticElectricity Buildupof charge from electronsthathave been
movedtoor froman insulator.
Sterilizing Usingionizingradiation(usuallygammarays) tokill
microorganismsonmedical equipment.
Supernova What happenswhenamassive starexplodesatthe
endof itslife.
Switch Circuitcomponentthatcan switchthe circuiton or
off by closingormakinga gap in the circuit.

28. Thermistor Special type of resistorwhose resistance decreases
as the temperature increases.
Time Base Tie interval representedbyeachhorizontal square on
an oscilloscope.
Time Period Time for one complete cycle of potential difference
for an alternatingcurrent.
Uranium235 Isotope of uraniumthatcan be usedto generate heat
innuclearpowerstations.
Variable Resistor Resistorwhose resistance canbe changed.
Voltage See potential difference.
White Dwarf White-hotcore leftafterthe outerlayersof a red
giantbreakaway.