6 Single layer of cells around the leaf: Upper and lower epidermis Flat, no chloroplaststo allow light to pass through
7 Waxy layer covering the upper epidermis CuticleWaxy layer covering the upper epidermisPrevents water loss
8 Layer of rectangular shaped cells found below the upper epidermis Palisade mesophyllLayer of rectangular shaped cellsfound below the upper epidermisCells arranged side by side, no spaces– traps as much sunlight as possibleMany chloroplasts – lots of photosynthesis
9 Layer of round cells below palisade cells Spongy mesophyllLayer of round cells below palisade cellsFewer chloroplasts, less photosynthesisAir spaces
10 oxygen, carbon dioxide and water Intercellular spacesSpaces between the spongy mesophyll cellsAllows diffusion ofoxygen, carbon dioxide and waterbetween inside the leaf and the air outside
11 Guard cells and Stomata A stoma is a small porefound between the cells of the lower epidermisGuard cellStomaTwo guard cells surround each stomaThey allow the stoma to open and close,controlling movement of gases in and out of the leaf
12 Contain vascular bundles made up of Midrib and VeinsContain vascular bundles made up ofxylem and phloemXylem carries water to the leaf cells from the rootsPhloem carries sucrose sugar made in the leaf cellsto other parts of the plant
13 ADAPTATIONSOF A LEAFFORPHOTOSYNTHESISCOMPLETE THE TABLEUSING PAGE 10 & 11
14 stomata investigation When stomata are open, water evaporates from the leaf.There are fewer stomata on the surface of a leafthan underneath becauseit is cooler under the leaf (less sunlight), so less water is lost.
21 How the materials for photosynthesis get to a palisade cell Watertravels from the roots up the xylem to the leavesCarbon dioxideenters the leaf through the stomataLightenters through the clear epidermis
22 How the materials for photosynthesis get to a palisade cell LIGHTworksheetHow the materials for photosynthesis get to a palisade cellchloroplastxylemWATERLEAF STRUCTURE WORKSHEETCARBON DIOXIDE
23 USING THE PRODUCTS OF PHOTOSYNTHESIS Glucose is the main product of photosynthesis.It is used in respiration to release energy.Glucose is also converted into other substances.Read page 22 and then complete the worksheet making notes on how the following are used by the plant.aminoacidsstarchcelluloselipids
24 ON TESTING A LEAF FOR STARCH Links to photos of girls carrying out exptTAKE NOTES FROM PAGE 19ON TESTING A LEAF FOR STARCH
29 results Leaf before testing Leaf after boiling in ethanol blue/black: contains starchorange: no starch
30 factors needed for photosynthesis experiments to showfactors needed for photosynthesisdestarchsoda limesodalimecarbon dioxidestencilLIGHTvariegatedchlorophyll
31 PHOTOSYNTHESIS experiments Worksheet In these experiments it is necessary to destarch the plant. Leave in dark for 48 hours. This removes any starch in the leaves andshows that if the starch test is positive, starch must have been made during the experiment.PHOTOSYNTHESISexperimentsWorksheet
32 1613 testing for OxygenBBC - Learning Zone Class Clips - Testing for oxygen produced by underwater plants - Science Video
33 CARBON DIOXIDE DISSOLVED IN WATER VOLUME OF oxygenCARBON DIOXIDE DISSOLVED IN WATEROxygenbubblesLIGHTLABEL PHOTO. PUPILS MAKE OWN NOTES ON HOW TO MEASURE RoP USING P20 TEXT BOOKMeasuring the rate of photosynthesis
34 pond weed produces bubbles of oxygen during photosynthesis. we can measure the rate at which PS occurs bycounting the number oxygen bubbles produced per minuteor by measuring the volume of oxygen produced per hour
35 experiments can be used to measure the rate of photosynthesis under different conditionslight intensity:a lamp is placed at different distances from the pondweedthe closer the lamp the more light is available for PSand the faster the rate of PS
36 to make this experiment a FAIR TEST only the light intensity should be changed;the carbon dioxide concentration,temperature, and pondweedmust remain the same
37 sodium bicarbonate releases carbon dioxide CO2 concentration:sodium bicarbonate releases carbon dioxidethe pondweed is set up with different concentrations of sodium bicarbonatethe higher the concentration of sodium bicarbonatethe more carbon dioxide is available for PSso the rate of PS increases
38 to make this experiment a FAIR TEST only the carbon dioxide concentration should be changed;the light intensity,temperature, and pondweedmust remain the same
39 the temperature of the water is increased by placing the beaker in a water bathat higher temperatures there is more energy availablefor chemical reactions to occurso the rate of PS increasesBUT very high temperature kill the plant, so PS slows and stops
40 to make this experiment a FAIR TEST only the temperature should be changed;the light intensity,carbon dioxide concentration,and pondweedmust remain the same
41 6021 Raw materials & products BBC - Learning Zone Class Clips - Plants and photosynthesis - Science Video
43 limiting factorsPhotosynthesis occurs at a maximum rate if all of the raw materials are readily available (light, carbon dioxide, water). Temperature also affects the rate of any chemical reaction.If any of these is in short supply it will limit the rate at which photosynthesis can occur.The substance limiting photosynthesis is called a limiting factor.
44 At the start of the graph increasing the light intensity increases the rate of photosynthesis. This shows that light is limiting the reaction and is the limiting factor.At the end of the graph the rate is constant. It does not increase any further, even though more light is available. This means that light intensity is no longer limiting the reaction and some thing else , such as temperature or carbon dioxide concentration, must be limiting the rate of photosynthesis.
46 By increasing the temperature the materials have more energy to react By increasing the temperature the materials have more energy to react. At the start this has no effect on the rate of photosynthesis compared to the lower temperature.The rate of photosynthesis is still limited by light intensity.In the middle of the graph the higher temperature provides more kinetic energy and therefore reactions can occur more quickly, more of the light can be used.At the end of the graph, even at higher temperatures, the rate of photosynthesis will level out. At this point another factor must be limiting the rate of photosynthesis e.g. carbon dioxide concentration.
49 Crop ProductionIn crop production it may be possible and profitable to control the environmental conditions to increase productivity.
50 GREENHOUSE Increase CO2 Burn fossil fuels e.g. paraffin Pipe in from canistersHUMIDITYOpen/close windows to control humidityGREENHOUSEMore photosynthesisMore growthBigger yieldLIGHTArtificial lightsused to increaselight intensity, daylength ANDseason lengthHEATUse electric heatersBurn fossil fuelsFERTILISERSOrganic e.g. manureInorganic e.g. NPK
51 The grower must consider the cost of increasing carbon dioxide concentration and temperature in the greenhouse.The cost of the raw materials must be balanced by the increase in productivity to maximise profit.
52 (It is the reverse equation for Photosynthesis!!) Balancing gasesAll living organisms respire during the day AND night .Remember:-Glucose + O CO2 + Water + EnergyThis is the equation for respiration(It is the reverse equation for Photosynthesis!!)
53 In plants the glucose and oxygen produced in photosynthesis can be used for respiration. The carbon dioxide and water produced in respiration can be used photosynthesis.Sometimes the two processes balance each other out.
54 Photosynthesis and respiration happen during the day Only respiration happens at nightHydrogen carbonate indicator can be used to show this relationship
55 Tube 1Tube 2Tube 3Tube 4PondweedMuslinWater BeetlesTinfoilRed – normal CO2Yellow – high CO2Purple – low CO2
56 Tube 1The tinfoil stops light getting to the plant. This is like night when there is no photosynthesisbut respiration still continues so CO2 is released from the plant, turning the hydrogen carbonate indicator yellow.
57 Tube 2There is a lot of light available to the plant.During the day the rate ofphotosynthesis is greater than therate of respiration so all the CO2 is taken up by the plant. The low CO2 level makes the hydrogen carbonate indicator purple.
58 THIS IS CALLED THE COMPENSATION POINT Tube 3The muslin reduces the light, this mimics dawn and dusk when the rate of photosynthesis is equal to the rate of respiration. All the CO2 released in photosynthesis is used in respiration (we say there is no net output of gas). The bicarbonate indicator does not change colour, it remains red.THIS IS CALLED THE COMPENSATION POINT
59 Tube 4The water beetles are respiring and therefore producing more CO2 than can be taken up in photosynthesis, causing the hydrogen carbonate indicator to turn yellow.