PHOTOSYNTHESIS

• What is the word equation for photosynthesis?

  Carbon Dioxide + Water -> Glucose + Oxygen
• Is photosynthesis an endothermic or exothermic reaction?

  Endothermic
• How can various factors change the rate of photosynthesis?

  • Temperature: Increases rate until enzymes denature
  • Carbon dioxide concentration: Increases rate until it's no longer limiting
  • Light intensity: Increases rate until it's no longer limiting
  • Chlorophyll concentration: Affects rate if minerals are lacking
• How are the products of photosynthesis used by plants?

  • Respiration for energy
  • Converted into insoluble starch for storage
  • Converted into fats or oils for storage
  • Used to make cellulose for cell walls
  • Used to make amino acids for proteins
• What is the equation for photosynthesis?

  Carbon Dioxide + Water -> Glucose + Oxygen
• Why is energy required to produce glucose molecules by photosynthesis?

  Because the reactions are endothermic
• What supplies the energy needed for photosynthesis?

  Sunlight
• What green chemical traps sunlight in plants?

  Chlorophyll
• Where is chlorophyll found in plant cells?

  Chloroplasts
• What is the limiting factor in photosynthesis?

  The factor stopping the reaction going faster
• How does temperature affect the rate of photosynthesis?

  It increases the rate to a point
• Why does increasing temperature increase the rate of photosynthesis?

  More energy is provided for the reaction
• Why does the rate of photosynthesis drop to zero at approximately 45°C?

  Enzymes controlling photosynthesis are destroyed
• How does carbon dioxide concentration affect the rate of photosynthesis?

  It increases the rate to a point
• Why does increasing carbon dioxide concentration increase the rate of photosynthesis?

  CO2 is needed in the reaction
• What happens when an increase in $CO_2$ has no further effect on photosynthesis?


  $CO_2$ is no longer the limiting factor
• How does light intensity affect the rate of photosynthesis?

  It increases the rate to a point
• Why does increasing light intensity increase the rate of photosynthesis?

  More energy is provided for the reaction
• What happens when an increase in light has no further effect on photosynthesis?

  Light is no longer the limiting factor
• How does chlorophyll concentration vary in the short term?

  It does not vary
• When might chlorophyll concentration change in plants?

  If plants lack minerals
• During photosynthesis, what form of energy is sunlight converted into?

  Chemical energy in glucose
• How can you determine the limiting factor by looking at a graph of photosynthesis rate?

  Identify the factor that plateaus
• How can greenhouses be used to increase the rate of photosynthesis?

  By controlling lighting, temp and CO2
• How can farmers increase the growth rate of their crops using greenhouses?

  By controlling lighting, temp and CO2
• In the provided graph, what is the limiting factor at low light intensity?

  Light intensity
• In the provided graph, what is the limiting factor at high light intensity?

  Temperature
• What practical investigation is described in the text?

  Effect of light on photosynthesis
• What is observed to measure the rate of photosynthesis in the pondweed experiment?

  Oxygen output
• In the sample method, what is placed in a beaker and illuminated with a lamp?

  A piece of pondweed
• What is recorded in the pondweed experiment to measure the rate of photosynthesis?

  Number of bubbles in one minute
• Why is it important to take multiple readings in the pondweed experiment?

  To calculate a mean
• Why is sodium hydrogen carbonate added to the water in the pondweed experiment?

  To provide carbon dioxide
• What is the independent variable in the pondweed experiment?

  Light intensity
• What is the dependent variable in the pondweed experiment?

  Number of bubbles in one minute
• What are the control variables in the pondweed experiment?

  • Piece of pondweed
  • Temperature
  • Concentration of carbon dioxide
• What is the main hazard to be aware of in the pondweed experiment?

  Water being dropped on the bulb
• What happens to light intensity when doubling the distance from the lamp?

  It reduces by a quarter
• What is the inverse square law?

  Doubling distance reduces light by quarter
• How might the glucose produced in photosynthesis be used by the plant?

  During respiration to provide energy