Biology Paper 1

• Limiting factor in photosynthesis

  The factor that is currently restricting the rate of photosynthesis
• Determining the limiting factor in photosynthesis

  1. Increase light intensity

  2. Increase carbon dioxide concentration

  3. Increase temperature
• Increasing light intensity


  Rate of photosynthesis increases initially
• Increasing light intensity further

  Rate of photosynthesis stops increasing
• Factors that limit photosynthesis

  • Light intensity
  • Carbon dioxide concentration
  • Temperature
  • Amount of chlorophyll in leaves
• Increasing carbon dioxide concentration

  Rate of photosynthesis increases
• Increasing carbon dioxide concentration further

  Rate of photosynthesis does not increase
• Increasing temperature


  Rate of photosynthesis increases
• If temperature is increased too much, enzymes in the leaf will start to denature and the rate of photosynthesis will fall
• Greenhouse


  Used by farmers to increase the rate of photosynthesis and crop yield
• How greenhouses increase the rate of photosynthesis

  1. Provide additional light

  2. Provide additional heat

  3. Increase carbon dioxide concentration
• Using greenhouses to increase photosynthesis is expensive, so the increase in yield has to justify the extra cost</b>
• As organisms get larger, the surface area : volume ratio falls sharply