28/05/13A typical plant cell:A typical plant cell:Cell wall – madeof cellulose whichstrengthens the cellCell membrane– controls whatcomes in and outNucleus – controlswhat the cell does andstores informationLarge vacuole –contains sap andhelps support thecellCytoplasm –Chemical reactionshappen hereChloroplasts (containingchlorophyll) – this is neededfor photosynthesis
28/05/13Plant cells have three “extra” things than animal cells:Plant cells have three “extra” things than animal cells:Both types of cell have these: Only plant cellshave these:NucleusCytoplasmCell wallLargevacuoleChloroplastsCellmembrane1)2)3)5)4)6)
28/05/13Some specialised cells we’ll come across…Some specialised cells we’ll come across…Palisade cells –found near thetop of a leafand are packedwithchloroplastsGuard cells –can open orclose to let inCO2 andregulate watercontentXylem – long andcylindrical to helptransport waterRoot hair cell – bigsurface area and thincell wall forabsorption ofnutrients and water
28/05/13PhotosynthesisPhotosynthesisPHOTOSYNTHESIS is when a plant makes its own food.Photosynthesis USES:Carbon dioxideWaterEnergy (from the sun)Photosynthesis PRODUCES:OxygenGlucose
28/05/13Four things are needed for photosynthesis:Travels upfrom the rootsWATERCARBON DIOXIDEEnters the leaf through smallholes on the underneathSUNLIGHTGives the plant energyCHLOROPHYLLThe greenstuffwhere thechemicalreactionshappen
28/05/13Photosynthesis happens in thePhotosynthesis happens in the“palisade” cells in the leaf:“palisade” cells in the leaf:Palisadecells
28/05/13Equations for photosynthesis:Carbon dioxide + _____ glucose + _____6CO2 + 6H20 C6H12O6 + 6O2SunlightChlorophyllSunlightChlorophyllThe GLUCOSE produced by photosynthesis is used by theplant for _______ (through ____________). It is storedin the plant as ___________.Words – respiration, starch, water, oxygen, energy
28/05/13Three factors can affect photosynthesis:Three factors can affect photosynthesis:1. Temperature – the best temperature isabout 300C – anything above 400C will slowphotosynthesis right down2. CO2 – if there is more carbon dioxidephotosynthesis will happen quicker3. Light – if there is more lightphotosynthesis happens faster
28/05/13Drawing graphs of these factorsDrawing graphs of these factors1. TemperaturePhotosynthesis is controlled byenzymes – these are destroyedat temperatures above 400C2. Carbon dioxide3. LightPhotosynthesis increases atfirst but is then limited by alack of increase in temp or CO2Photosynthesis increases atfirst but is then limited by alack of increase in temp or light
28/05/13What is the glucose used for?What is the glucose used for?1) Glucose (sugar) can be used to make long chains of starch…GlucosemoleculesStarchmolecule2) Glucose can be used to make cellulose for cell walls…3) Glucose can be combined with nitrates to make proteins (for growth)…4) Glucose can be converted into lipids (fats or oils) to store in seeds…GlucosemoleculesGlucosemoleculesGlucosemoleculesCelluloseProteinsLipid structure
28/05/13Xylem and phloemXylem and phloemXylem vesselstransport waterfrom the root tothe leaf andstem to replacethe water lostthroughtranspiration.Phloem cells transportnutrients from the leavesto the rest of the plant.
28/05/13Plant growthPlant growthPlants also needthree importantminerals to keephealthy. Theyabsorb thesethrough their roots.Plants grow using food they make throughphotosynthesis. So what else do they need?
28/05/13The 3 main nutrients…The 3 main nutrients…Potassium: Helps the enzymes that are needed forphotosynthesis Lack of it leads to yellow leaves with deadbitsNitrates: Used to make proteins Lack of it leads to a small plant, yellowleavesPhosphates: Used to provide phosphorus to helpphotosynthesis and respiration Lack of it leads to small roots and purpleleaves
28/05/13TranspirationTranspiration1) Water evaporatesthrough the stomata2) Water passes back into theleaf through the XYLEM vesselsby osmosis3) Water is then pulled upwardsthrough the xylem tissue4) This is replaced by waterentering from the root tissue5) Water enters root hair cells byosmosis to eventually replace thewater lost through respiration
28/05/13RoothaircellsPlant roots are made of “root hair cells” which have alarge surface area and a thin cell membrane to helpabsorb water and minerals:Thin cell membraneLarge surface area
28/05/13Water lossWater lossWater loss through the stomata is biggest on ahot, dry, windy day. Plants that live in theseconditions often have a thicker waxy layer.
28/05/13Controlling water lossControlling water lossCarbon dioxide enters a leaf through the ________. Thesecells are also responsible for controlling the ______ contentof the leaf…The ______ cells control how wide thestomata opens (if at all). If too muchwater is being lost through the stomatathen the guard cells will _____ to preventfurther loss.Water and carbondioxide enter here No more waterand carbondioxide allowed in
28/05/13Turgor pressureTurgor pressureConsider a plant that’s been well watered:Because there is a _______ concentrationof water in the soil than in the ____,water will enter the plant cells through_______ and the cells will becomeTURGID (“_________”):In this case thestomata will ______ toallow carbon dioxide inand water ___ andphotosynthesis willcarry on.Words: out, swollen,higher, soil, osmosis,open
28/05/13Turgor pressureTurgor pressureConsider a plant that’s been badly watered:Because there is a lower concentration ofwater in the soil than in the plant water willleave the plant cells through osmosis andthe cells will become FLACCID (“soft”):In this case the stomata will close to stop waterfrom escaping through transpiration. Because theyare closed carbon dioxide cannot get in and sophotosynthesis stops.Turgid = “tense” Flaccid = “floppy”
28/05/13DiffusionDiffusionDiffusion is when something travels from an area of highconcentration to an area of low concentration. For example,consider the scent from a hamburger…The “scent particles” fromthis hamburger are in highconcentration here:Eventually they will“diffuse” out into this areaof low concentration:
28/05/13OsmosisOsmosisOsmosis is a “special kind of diffusion”. It’s when water diffuses from aconcentrated area to a less concentrated area through a partiallypermeable membrane (i.e. one that allows water to move through but notanything else):Water Sugar solutionIn this example the watermolecules will move from leftto right (along theconcentration gradient) andgradually dilute the sugarsolution.This is how water moves intoroot hair cells
28/05/13Active TransportActive TransportActive transport is when substances are absorbed _______ aconcentration gradient (like a ball being rolled ___ a hill).This takes place in the opposite direction to normal _______.This is how nitrates are taken in by root hair cells:Root haircells “pull”more nitrateions inThis process needs ________ (just like rolling a ball up a hillwould). This energy is provided by __________.Root hair cellalready has a largeconcentration ofnitrate ionsWords – energy, up, respiration, diffusion, against
28/05/13Plant hormonesPlant hormonesIn the shoot the growth hormonescollect on the ____ side, causing it to_____ more there and bend _____ awayfrom the force of ______.Hormones STIMULATE growth inSHOOTS.In the root hormone also collects on thelower side, but this time it _____ _____growth, causing the root to grow_______ towards gravity.Hormones RETARD growth in ROOTS.Words: upwards, downwards, slows down, lower, grow, gravity
28/05/13Other interesting facts…Other interesting facts…In shoots, light causes hormones to collect in the shaded partof the stem, causing the shoot to grow towards the sunlight.Artificial hormones can also be used to kill weeds, controlwhen a plant ripens, help many plants grow from one stem andother exciting uses…
28/05/13The Nervous SystemThe Nervous SystemThe NERVOUS SYSTEM consists mainly of the brain, thespinal cord, nerve cells (“neurones”) and receptors.Types of receptor:1) Light receptors in the eyes2) Sound receptors in the ears3) Taste receptors on the tongue4) Smell receptors in the nose5) Touch, pressure and temperature receptors in the skin6) Changes of position receptors in the ears (balance)Stimulus Receptor Coordinator Effector Response
28/05/13Examples of reactionsExamples of reactionsStimulus Receptor(i.e. the thingthat detects thestimulus)Effector(i.e. the thingthat will do thereaction)Response(i.e. actiontaken)Bright lightSour tasteLosing balanceSit on a drawingpin
28/05/13Types of nerve cellTypes of nerve cellNucleus Muscle strands(effector)Cell body1) Motor neurone 2) Sensory neurone 3) Relay neuroneImpulse ImpulseNerve cells (neurones) are elongated with branchedendings to connect to many muscles fibres.
28/05/13Conscious actionsConscious actionsA conscious action is one where the brain makes a considered response.Here’s what happens:Stimulus Receptor Sensory Neurone CoordinatorMotor Neurone Effector Response1) Receptors inyour skin detecta stimulus3) Here another sensory neuronecarries the signal to the brain4) The braindecides to moveaway the hand5) This impulse issent by MOTORNEURONES to thehand muscles (theeffectors) via thespinal chord…2) The impulse is carriedby SENSORY NEURONESto the spinal chord6) Which thenmoves the handaway
28/05/13Reflex actionsReflex actionsSometimes conscious action is too slow to prevent harm, e.g…In situations like thisthe body bypasses thebrain to produce aquicker response.Here’s how it works…
28/05/13SynapsesSynapsesNeurones never touch each other – there is a small gapbetween them called a SYNAPSE. A signal is sent from oneneurone to the next by a chemical transmitter across thesynapse. These transmitters are then destroyed.
28/05/13Seeing thingsSeeing thingsRays of light are refracted(bent) first by the corneaand then by the lens. Theyfocus on the retina.
28/05/13Seeing things at different distancesSeeing things at different distancesFor distant objects theciliary muscles relaxand the suspensoryligaments pull tightmaking the lens pullthin – the light doesn’tbend as much.For close objects theciliary muscles contractallowing the lens to gofat, thus bending thelight more.
28/05/13HomeostasisHomeostasisHomeostasis means “controlling internal conditions”:Waste products that need to be removed + howCO2UreaInternal conditions that need controlling + howTemperatureIon contentWater contentBlood glucoseProduced by respiration, removed via lungsProduced by liver breaking down amino acids,removed by kidneys and transferred to bladderIncreased by shivering, lost by sweatingIncreased by eating, lost by sweating + urineIncreased by drinking, lost by sweating + urineIncreased and decreased by hormones
28/05/13Controlling body temperatureControlling body temperatureBody temperature is controlled by the thermo-regulatory centre in the________. It is kept at 370C as this is the best temperature for__________ to work in. If the body becomes too hot then bloodvessels _________ and sweat glands release ________. If the body istoo ______ then blood vessels constrict and muscles start to__________.Words – sweat, enzymes, cold, dilate, shiver, brain
28/05/13KidneysKidneysBlood inBlood outUreter (tube that takesurine down to bladder)Kidneys are made up of twoimportant tissues – BLOODVESSELS and TUBULES.Kidneys are responsible for controlling ion, urea andwater content.
28/05/13KidneysKidneysKidneys work in 3 stages:1. ULTRAFILTRATION - Lots of water andproducts of digestion are squeezed out ofthe blood and into tubules under pressure.3. WASTE – excess water, excess ions andany urea are now removed through theureter2. SELECTIVE REABSORPTION – the bloodtakes back the things it wants (e.g. glucoseand ions) even though this means goingagainst a concentration gradient.Blood vessel Tubule
28/05/13Controlling water contentControlling water contentThe amount of water reabsorbed into the blood vessels inthe kidney is controlled by the hormone ADH:
28/05/13Controlling GlucoseControlling GlucoseThe amount of glucosein our blood (“bloodsugar level”) iscontrolled by thepancreas…
28/05/13Controlling GlucoseControlling GlucoseThe amount of glucose inour blood is controlled bythe hormones insulin andglucagon working with thePANCREAS:Glucose returns to normal
28/05/13DiabetesDiabetesDiabetes is a ________ in which a person’s blood sugar(i.e. glucose) level may rise to a _______ level. This isbecause the ______ doesn’t produce enough _________.Diabetes can be treated by __________ carefully or byinjecting extra insulin when needed. Diabetics have totest their blood sugar level before they decide how muchinsulin to _______ themselves with.Words – insulin, disease, inject,dangerous, eating, pancreas
28/05/13Smoking, drugs and alcoholSmoking, drugs and alcoholSmokingDrugsAlcohol
28/05/13SmokingSmokingCigarettes contain 3 harmful things:1. NICOTINE, which is an ___________ drug that raisesthe heart beat, narrows the arteries and so causes____ _____ _____. This leads to heart _________.2. TAR, which coats the lining of the _______ makingthem less able to take in oxygen. It also containscarcinogens which cause ______________.3. CARBON MONOXIDE, which is a _______ ____ whichjoins up with ____ blood cells making them incapable oftransporting _____________ around the body.Words – high blood pressure, oxygen, red, addictive,disease, poisonous gas, lungs, cancer
28/05/13Damaging the alveoli (emphysema)Damaging the alveoli (emphysema)Before smoking After smoking – lesssurface area