required practical 6 - investigating the effect of light intensity on the rate of photosynthesis in pondweed

Set up equipment as so and count bubbles produced in 1 minute. Move light source back 10cm and repeat.

Problems + improvements

Human error, counting bubbles produced incorrectly - clicker counter or have multiple counters

External light sources - dark room, blackout curtains

Sizes of bubble may vary - gas syringe or count 2 for large bubble ½ for small

Lamp also increases temperature - standard dose by keeping test tube in water bath

Using a gas syringe also can be used to adapt the method to enable you to compare the volume of oxygen given off at each light intensity