Photosynthesis

• Photosynthesis


  A chemical reaction in which energy is transferred from the environment as light from the Sun to the leaves of a plant. This is an endothermic reaction.
• Chlorophyll


  • The green pigment in chloroplasts in the leaves that absorbs the light energy
  • Leaves are well-adapted to increase rates of photosynthesis
• Limiting factor


  Anything that limits the rate of a reaction when it is in short supply
• Limiting factors for photosynthesis

  • Light intensity
  • Temperature
  • Carbon dioxide concentration
  • Amount of chlorophyll
• Less chlorophyll in the leaves


  Reduces the rate of photosynthesis
• More chlorophyll produced by plants in well-lit areas


  Increases the photosynthesis rate
• Photosynthesis


  Carbon dioxide + water -> glucose + oxygen
• Limiting factors and photosynthesis rate

  • At low temperatures, the rate is low because reactant molecules have less kinetic energy
  • At high temperatures, the enzymes are denatured and the rate quickly decreases
  • Increasing carbon dioxide concentration increases the rate of photosynthesis until another factor becomes limiting
  • Increasing light intensity increases the rate of photosynthesis until another factor becomes limiting
• Inverse square law


  As the distance of a light source from a plant increases, the light intensity decreases in inverse proportion to the square of the distance
• Commercial greenhouses control limiting factors to get the highest possible rates of photosynthesis so they can grow plants as quickly as possible or produce the highest yields, whilst still making profit
• Uses of glucose produced in photosynthesis


  • Converted into insoluble starch for storage
  • Used for respiration to release energy
  • Used to produce cellulose to strengthen cell walls
  • Used to produce fat or oil (lipids) for storage
  • Used to produce amino acids for protein synthesis
• Retrieval


  Learn the answers to the questions below then cover the answers column and write as many as you can. Check and repeat
• B11 questions
• Where does photosynthesis occur?

  • Chloroplasts in the leaves of a plant
• Chlorophyll


  The green pigment in the leaves
• Photosynthesis


  A type of endothermic reaction
• Energy used in photosynthesis

  Light energy
• Word equation for photosynthesis

  Carbon dioxide + water -> Glucose + oxygen
• Balanced symbol equation for photosynthesis

  6CO2 + 6H2O -> C6H12O6 + 6O2
• Limiting factor


  Anything that limits the rate of a reaction when it is in short supply
• Limiting factors of photosynthesis

  • Temperature
  • Carbon dioxide concentration
  • Light intensity
  • Amount of chlorophyll
• Light intensity


  Increasing light intensity increases the rate of photosynthesis until another factor becomes limiting
• Carbon dioxide concentration


  Increasing carbon dioxide concentration increases the rate of photosynthesis until another factor becomes limiting
• Temperature


  Increasing temperature increases the rate of photosynthesis as the reaction rate increases, but at high temperatures enzymes are denatured so the rate of photosynthesis quickly decreases
• Inverse square law for light intensity

  Light intensity is inversely proportional to the square of the distance from the light source
• Limiting factors are important in the economics of growing plants in greenhouses to produce the maximum rate of photosynthesis while making profit
• How plants use the glucose produced in photosynthesis

  • Convert it into insoluble starch for storage
  • Produce fat or oil for storage
  • Produce cellulose to strengthen the cell wall
  • Produce amino acids for protein synthesis