Photosynthetic rate HT: Bioenergetics: Biology: GCSE (9:1)

• Photosynthetic rate


  The rate at which plants take in carbon dioxide, water and the energy from sunlight to produce glucose
• Chlorophyll


  A green pigment in plants that absorbs light energy used to carry out photosynthesis

  
• Role of enzymes

  Photosynthesis is an enzyme-controlled reaction where the enzymes are needed to convert carbon dioxide into glucose
• Temperature


  Increases the rate of reaction up to an optimum rate, after which the denaturation of enzymes will occur

  
• Sunlight


  Is needed as an energy source for photosynthesis to occur

  
• Carbon dioxide (CO2)


  Enters the plant through the stomata during gas exchange and is the source of carbon needed to make glucose

  
• Temperature effect


  Photosynthesis rate increases to an optimum and then decreases due to denaturing enzymes

  
• Light intensity effect


  Photosynthesis rate increases and then plateaus due to another limiting factor such as temperature or carbon dioxide

  
• Carbon dioxide concentration effect

  Photosynthesis rate increases and then plateaus due to another limiting factor such as temperature or light intensity

  
• Chlorophyll effect


  Plants with diseases or variegated leaves may have less chlorophyll which reduces the rate of photosynthesis

  
• Limiting factor


  An environmental factor that prevents photosynthetic rate from increasing

  
• Three main limiting factors

  Temperature, light intensity and carbon dioxide concentration

  
• Plateau


  Where a graph levels off and no longer increases past a certain point

  
• Inverse-square law

  Light intensity is inversely proportional to the square of the distance from a light source

  
• Inversely proportional relationship


  As the distance of light from a plant increases, the light intensity decreases