Photosynthesis

• Plants are called producers in food chains
• Photosynthesis


  An endothermic reaction in which energy is transferred from the environment to the chloroplasts by light
• Leaves


  • Where most photosynthesis takes place, in specialised mesophyll cells packed with chloroplasts containing chlorophyll to absorb as much light energy as possible
• Photosynthesis


  Can be summarised into a simple equation
• Photosynthesis is an endothermic reaction
• Balanced Symbol Equation.

  • 6CO2+6H2O→C6H12O6+6O2
• carbon dioxide + water → glucose + oxygen
• Light energy → Chemical energy
• Factors that affect photosynthesis


  • Light
  • Water
  • Carbon dioxide
  • Temperature
  • Chlorophyll
• Effect of temperature on the rate of photosynthesis


  1. Lower temperature: less kinetic energy, fewer successful collisions

  2. Higher temperature: more kinetic energy, more collisions

  3. Highest temperature: enzyme denaturation, reduced rate
• Chlorophyll


  • The pigment in chloroplasts that absorbs light energy for photosynthesis
  • The more chloroplasts a plant has, the faster the rate of photosynthesis
• Factors that can affect the amount of chlorophyll


  • Diseases (such as tobacco mosaic virus)
  • Lack of nutrients (such as magnesium)
  • Loss of leaves (fewer leaves means fewer chloroplasts)
• Limiting factors


  Important in the economics of enhancing conditions in greenhouses to gain maximum rate of photosynthesis while still maintaining profit
• • The glucose produced in photosynthesis may be:
  • Used for respiration (both aerobic and anaerobic)
  • Converted into insoluble starch for storage in the stems, leaves and roots
  • Used to produce fat or oil for storage (especially in seeds)
  • Used to produce cellulose, which strengthens the cell wall
  • Combined with nitrate ions absorbed from the soil to produce amino acids for protein synthesis