2.22 describe experiments to investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon dioxide and chlorophyll

Testing plant for presence of starch:

1.      Place leaf in boiling water for 1 minute to soften it

2.      Turn off the Bunsen burner and Place leaf into test tube half full of ethanol and lace the test tube in the hot water for 10 minutes

3.      Spread the leaf out on a Petri dish and cover it with iodine

4.      Return the leaf to the hot water for about a minute

5.      If starch is present the leaf will turn black and blue

Experiments to test the limiting factors:

1.      Light intensity:

·         Move the light bulb to a measured distance away from water plant

·         Measure the volume of oxygen released by the plant in set period of time

·         Move the light bulb to a different distance to vary the intensity

2.      Carbon dioxide:

·         Add a concentration of sodium hydroxide carbonate (eg 0.1%) to the plant’s water

·         Measure the volume of oxygen over set amount of time

·         Add a different concentration of oxygen each time

3.      Temperature:

·         Change the temperature of the plant’s water

·         Measure the volume of oxygen produced over set period of time