The effect of light intensity on photosynthesis can be investigated in water plants such as Cabomba or Elodea, types of pond weed, which are sold in aquarium shops.
The plants will release bubbles of oxygen, a product of photosynthesis, which can be counted.
To investigate the effect of light intensity on the rate of photosynthesis.
A lamp with an LED bulb is set up at different distances from the plant in a beaker of water:
The bubbles produced over one minute periods are recorded. The rate of photosynthesis is the number of bubbles produced per minute.
Care must be taken when using water near electrical equipment. Ensure that your hands are dry when handling the lamp.
The volume of oxygen produced could be measured by collecting the gas produced in a gas syringe.
The changes in the oxygen concentration in the water could be measured using data logging equipment.
You could investigate the effect of different wavelengths of light on photosynthesis.
Use coloured acetate filters to investigate the effects of the blue, green and red parts of the spectrum on photosynthesis.