Investigating Photosynthesis

Question 1

Describe how limiting factors can be investigated using pond weed

Answer 1

• a test tube containing the pond weed and water is connected to a capillary tube full of water which is connected to a syringe (photosynthometer)
• a source of white light is placed at a specific distance from the pondweed
• the pondweed is left to photosynthesise for a set amount of time, the oxygen released will collect in the capillary tube
• at the end of the experiment the syringe is used to draw the gas bubble in the tube up alongside a length of ruler and the length of the gas bubble is measured (vol of O2)
• experiment should be repeated and average used
• can carry out experiment with light at different distances or at different temperatures