Bioenergetics paper 1

• Plants use light as their source of energy
• Photosynthesis is the reaction that plants use to trap light energy
• All the energy needed for a plant to grow comes from the light energy trapped by photosynthesis
• Photosynthesis is an endothermic reaction
• Photosynthesis takes place in the leaves of a plant
• Leaves contain the green chemical chlorophyll, which can absorb light energy
• In the first stage of photosynthesis, the plant takes in carbon dioxide and water into the leaf
• Light energy is absorbed by chlorophyll and used to convert carbon dioxide and water into glucose and oxygen
• The word equation for photosynthesis is: carbon dioxide + water -> glucose + oxygen
• Chemical formulas:

  • Carbon dioxide: CO2
  • Water: H2O
  • Glucose: C6H12O6
  • Oxygen: O2
• • At a certain point, carbon dioxide is no longer the limiting factor
  • Amount of chlorophyll in the leaf:
  • Leaves with less chlorophyll trap less light energy and have a lower rate of photosynthesis
  • Temperature:
  • Increasing temperature speeds up the enzymes involved in photosynthesis, increasing the rate
  • Enzymes denature at high temperatures, causing the rate of photosynthesis to fall
• Factors affecting the rate of photosynthesis:

  • Light intensity:
  • Rate of photosynthesis increases with increased light intensity
  • Light intensity is a limiting factor when the rate of photosynthesis increases with increased light intensity
  • At a certain point, light intensity is no longer the limiting factor
  • Carbon dioxide level:
  • Rate of photosynthesis increases with increased carbon dioxide level
  • Carbon dioxide is the limiting factor when the rate of photosynthesis increases with increased carbon dioxide level