Photosynthesis

• What are the reactants for Photosynthesis?

  Carbon dioxide and water
• How does water enter a plant?

  Through the roots and travels upwards through the xylem.
• How does Carbon Dioxide enter a plant and via what process?

  Enters via the stomata through diffusion
• What are the products for Photosynthesis?


  Glucose and oxygen
• What is also needed for photosynthesis to occur?


  Sunlight and (thermal/heat) energy is needed
• Where does photosynthesis occur in a plant?


  Chloroplasts
• Where does photosynthesis occur in a leaf?


  The Palisade Mesophyll part of a leaf as this is the part that contains chloroplasts
• What type of reaction is Photosynthesis?

  Enzyme-based reaction
• Is Photosynthesis exothermic or endothermic?

  Endothermic
• What factors affect the rate of photosynthesis?

  Temperature (optimum temp prevents enzyme denaturing)

  Light Intensity

  Carbon Dioxide Concentration

  Amount of chlorophyll
• What equipment would you use to investigate the effect of light intensity on the rate of photosynthesis?

  Elodea plant (Pondweed)

  light source

  large glass beakers

  metre ruler

  paper clip

  Sodium-Hydrogen Carbonate (SHC)

  boiling tube
• Step 1 of the Photosynthesis practical is...

  Fill a boiling tube one third full with Sodium Hydrogen Carbonate
• Step 2 of the Photosynthesis practical is...

  Place the pondweed in the boiling tube
• Step 3 of the Photosynthesis practical is...


  Use the paper clip to weigh the pondweed down to the bottom of the boiling tube.
• Step 4 of the Photosynthesis practical is...

  Fill up a glass beaker with tap water
• Step 5 of the Photosynthesis practical is...

  Place the boiling tube in the glass beaker and lean it on the side of the beaker
• Step 6 of the Photosynthesis practical is

  Place a metre ruler next to the glass beaker
• Step 7 of the Photosynthesis practical is..

  Start by counting the bubbles that the plant releases for one minute and record your findings.
• Step 8 of the Photosynthesis practical is...

  Place a lamp (or any light source) at 10 cm away from your beaker - keep it switched off
• Step 9 of the Photosynthesis practical is...

  Turn the light source on for a minute and count and record the number of bubbles released by the plant
• Step 10 of the Photosynthesis practical is..

  Move the lamp along 10 cm
• Step 11 of the Photosynthesis practical is..


  Repeat from Step 9 until you have recorded the bubbles released at every length up to 60 cm
• How can we make the Photosynthesis practical more accurate?

  Use a gas syringe to collect the volume of gas produced.

  Repeat the experiment at least twice at each distance and calculate the mean volume of gas produced at each distance.

  Use of a heat shield between the lamp and plant to prevent heating of the plant - or use a LED lamp that is more efficient.