Photosynthesis

• Set up a beaker with pondweed inside
• Place the beaker 10cm away from the light source
• Turn the light on and leave the pondweed for 5 minutes
• Count the number of bubbles produced in a fixed period of time or measure how much gas is collected in a fixed period of time using a gas syringe
• Repeat to identify anomalees and calculate averages
• Repeat for different distances and temperatures
• You leave the pondweed 5 minutes after the lamp has been turned on before counting bubbles to give the pondweed time to acclimatise
• Use a lamp with a LED bulb
• Sodium hydrogen carbonate may be added tot he water to ensure that there is an excess of carbon dioxide
• Bubbles are produced by the pondweed during the photosynthesis experiment because oxygen is a product of photosynthesis and so when the pondweed photosynthesises it makes bubbles of the gas that we can count
• The temperature can be controlled by adding the pondweed sample to a beaver of water to help maintain the temperature
• Discs would rise to the surface because they have made oxygen which causes them to float to the surface