|Leaf Structure. -Cuticle -Upper epidermis -Palisade mesophyll cell -Bundle sheath cell -Xylem -Phloem -Lower epidermis Spongy mesophyll cells -Guard cell -Stoma -Cuticle -Vein
|Carbon Dioxide + Water -> Glucose + Oxygen
|1. Keep leaf in dark cupboard (48hrs) Then place in light for 24 hrs. This will prove that any starch formed was formed during the experiment. 2.Boil the leaf in water 3.Place in boiling hot ethanol (to remove the chlorophyll) 4.Dip the leaf back in water to soften it 5.Spread across a white tile and add iodine
|Colour Change for iodine red/brown------>blue/black
|Showing Chlorophyll is needed for photosynthesis A plant with variegated leaves is de-starched and then allowed to photosynthesise (light,carbon dioxide and water all present). Iodine is added, if chlorophyll is present, the iodine will turn blue/black, if not it will remain brown
|Showing light is needed for photosynthesis A plant is de-starched and then some of its leaves are covered in black paper/silver foil. The plant is then allowed to photosynthesis for 24 hours. The leaf is then tested for starch. If it has worked the covered section of the leaf should have no starch present and the rest should have starch present.
|Showing Carbon Dioxide is needed for Photosynthesis You can remove carbon dioxide from the atmosphere by adding KOH (potassium hydroxide) or soda lime (sodium and calcium hydroxide). So to test, pace aplant in a glass jar with KOH and one without any extra substances. If it has worked correctly, the glass jar with KOH should have nostarch present and the other one should have starch present.
|-Soda lime and Potassium Hydroxide solution (any hydroxide) remove Carbon Dioxide from the air. -Hydrogen carbonate solutions add carbon dioxide to water
|How to measure the rate of Photosynthesis. 1. Collect the volume of Oxygen produced over a period of time. 2.Collect the glucose produced over a period of time 3.Measure the volume of Carbon Dioxide taken into the plant over a period of time
|Factors effecting the rate of photosynthesis Light Intensity- If you increase light intensity you will increase the rate of photosynthesis. Light intensity will only increase the rate up to a certain point and then the rate 'levels off'. At this point something else must be the limiting factor
|Carbon Dioxide concentration- also has an effect on the rate of photosynthesis. If you increase the Carbon Dioxide concentration you increase the rate of photosynthesis- up until a certain point and then some other factor limits the reaction rate. The concentration of carbon dioxide can be changed using different concentrations of sodium hydrogencarbonate solution.
|Temperature- an increase in temperature will increase the rate of photosynthesis. However if you continue to increase the temperature the reaction will slow down and eventually stop as you destroy (denature) the enzymes controlling the reaction
|Oxygen- used by the plant in respiration- any excess is removed from the leaf by diffusion through the stomata Glucose- very quickly converted into starch. This starch can then be stored. The starch can be quickly broken back into glucose when necessary to be used in respiration or converted into other essential plant products -
|Cellulose- This is the main component of plant cell walls Amino acids and lipids- The glucose that is produced can be converted into amino acids and eventually proteins by a series of reactions in plant cells. Lipids can be used as an energy store. Starch- In the storage parts of a plant, e.g roots. Many of the foods we eat contain starch from plants
|Colour of Hydrogen Carbonate Indicator High Carbon Dioxide levels-YELLOW Normal Carbon Dioxide Levels-RED Low Carbon Dioxide Levels-PURPLE
|Hydrogen Carbonate indicator- can help scientists find out what gases are moving in and out of plants. Compensation Point- Rate of photosynthesis=Rate of respiration
|Economic implications in crop production- Farmers and crop growers want to make sure that they get the maximum rate of photosynthesis in plants that they are growing because this will give bigger plants with lots of stored starch. They do this by making sure they have all the raw materials needed for photosynthesis (co2, water, heat + light) It is easier to control the factors affecting photosynthesis in a greenhouse than open air.
|Examples of environmental factors that can be increased/enhanced are- -increasing temperature -increasing carbon dioxide levels -increasing light intensity -increasing fertiliser applications -increasing water availability
|Paraffin heaters- are often used to increase both temperature and carbon dioxide levels. Water sprinklers and artificial lighting are also frequently used. All of these things cost money but hopefully will ensure a bigger profit as the productivity of the plant is increased
|variegated elodea light absorption mesophytic leaf intercellular spaces