Photosynthesis

• Photosynthesis uses energy to change water and carbon dioxide into glucose and oxygen.
• Photosynthesis takes place in the chloroplasts which contain pigments like chlorophyll which absorbs light.
• Photosynthesis is an endothermic process.
• $6CO_2+$$6H_2O\rightarrow C_6H_{12}O_6+$$6O_2$


  Symbol equation for photosynthesis.
• Plants use glucose for respiration which converts glucose into various other useful substances.
• Plants use glucose to make cellulose which strengthens plant cell walls.
• Plants combine glucose and nitrate ions to make amino acids which are then made into proteins.
• Plants can turn glucose into lipids and store in seeds.
• Plants store glucose as insoluble starch.
• The limiting reactant is a factor that stops a reaction from going any faster.
• The rate of photosynthesis can be affected by

  • Light intensity
  • Concentration of CO2
  • Temperature
  • Amount of chlorophyll
• If the temperature is too low the enzymes will work slowly and if the temperature is too high the enzymes will denature


  The peak of the graph shows the optimum temperature for the enzymes

  
• The intensity of light increases the rate of photosynthesis until it is no longer the limiting factor


  Light effects rate of photosynthesis

  
• The carbon dioxide concentration increased the rate of photosynthesis until it is no longer the limiting factor


  Carbon dioxide concentration affects the rate of photosynthesis.

  
• Rate of photosynthesis practical

  • A source of white light is placed at a specific distance away from the pondweed
  • The pondweed is left to photosynthesise for a set amount of time
  • Oxygen released will be collected in a capillary tube which contains water
  • A syringe draws out the gas bubble and the length of the gas bubble is measured
  • This is repeated to get and average
  • This can be repeated with a different distance of the light
• $Light\:Intensity \propto \frac{1}{distance^2}$


  Light intensity is inversely proportional to distance squared
• Greenhouses are a common way to artificially create an ideal environment for plants
• Greenhouses advantages

  • Trap the suns heat so temperature does not become a limiting factor
  • Provides artificial light if needed
  • Can control carbon dioxide levels
  • Better crop
  • Keeps plants safe from diseases