The rate of photosynthesis

• What three factors affect the rate of photosynthesis?

  Light, CO₂, and temperature
• How does light intensity affect the rate of photosynthesis?

  Rate increases with light intensity until a limit
• What happens to the rate of photosynthesis beyond a certain light intensity?

  It no longer increases due to limiting factors
• How can you change the light intensity in a lab experiment?

  By moving a lamp closer or further away
• What type of graph is produced when plotting the rate of photosynthesis against lamp distance?


  A weird-shaped graph
• What is necessary to obtain a proper graph of photosynthesis rate?

  Measure light intensity with a light meter
• What is the first important factor that slows down the rate of photosynthesis?

  Not enough light
• Why does the rate of photosynthesis stop increasing with high light intensity?

  Because temperature or CO₂ becomes limiting
• What is the second important factor that slows down the rate of photosynthesis?

  Too little carbon dioxide
• What are the key points about light's role in photosynthesis?

  • Light provides energy for photosynthesis
  • Rate increases with light intensity
  • Rate plateaus at a certain light level
  • Limiting factors become temperature or CO₂
• What is one of the raw materials needed for photosynthesis?

  CO₂
• How does the amount of CO₂ affect the rate of photosynthesis?

  It increases the rate up to a point
• What happens to the rate of photosynthesis after CO₂ reaches a certain level?

  The rate no longer increases
• What indicates that CO₂ is no longer the limiting factor in photosynthesis?

  The graph flattens out with increased CO₂
• What factors must be in plentiful supply for photosynthesis to occur efficiently?

  Light and CO₂
• What is the limiting factor for photosynthesis when theres large amounts of light and CO₂?

  Temperature
• What conditions are necessary for most effective photosynthesis?

  • Plenty of light
  • Sufficient CO₂
  • Appropriate temperature
• What happens to the rate of photosynthesis if light or temperature needs to be increased?

  The rate will not be optimal
• What does the graph of photosynthesis rate show when CO₂ is increased?

  It flattens out after a point
• What does a flat graph indicate about CO₂'s role in photosynthesis?

  CO₂ is no longer limiting the process
• What is the effect of low temperatures on photosynthesis enzymes?

  They work more slowly
• Why is high temperature a limiting factor for photosynthesis?

  It damages the enzymes needed for photosynthesis
• At what temperature do enzymes for photosynthesis get damaged?

  About 45 °C
• Why can greenhouses reach high temperatures?

  Because they can trap heat if not managed
• What are the assumptions of temperature on photosynthesis?

  • Low temperatures slow down enzyme activity
  • High temperatures can damage enzymes
  • Optimal temperature is important for effective photosynthesis