Interaction of Limiting Factors

• What are the three key factors that can be altered to study their effect on photosynthesis?

  Light intensity, carbon dioxide, temperature
• How does light intensity affect the rate of photosynthesis?

  It increases with higher light intensity
• How can you test the effect of light intensity on photosynthesis?

  By placing a light source at different distances
• What does the inverse square law describe?

  The relationship between distance and light intensity
• What happens to light intensity when the distance from the light source is doubled?

  It falls by a factor of four
• What is the formula for relative light intensity according to the inverse square law?

  $1 / \text{distance from light source}^2$
• Does relative light intensity have a unit?

  No, it does not have a unit
• How is relative light intensity compared?

  With a source placed at a distance of 1 m
• What happens to the units when calculating relative light intensity?

  The units are cancelled out
• What organism can be used to investigate the rate of photosynthesis?

  Elodea (pondweed)
• How is the rate of photosynthesis measured using Elodea?

  By counting the number of bubbles produced per minute
• What does the volume of oxygen given off indicate in photosynthesis?

  It measures the rate of photosynthesis
• What are the three key factors that can be altered to study their effect on the rate of photosynthesis?

  • Light intensity
  • Carbon dioxide concentration
  • Temperature
• How can light intensity be altered in a photosynthesis experiment?

  By placing a light source at different distances
• How can carbon dioxide concentration be increased in the experiment?

  By adding potassium hydrogen carbonate powder
• What does potassium hydrogen carbonate do in the experiment?

  It releases carbon dioxide to the atmosphere
• How can temperature be varied in the photosynthesis investigation?

  By placing the apparatus in water baths
• What is the purpose of measuring the rate of photosynthesis?

  To understand how different factors affect it