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Aim: Verify the relationship between light intensity and photosynthesis

IV ~ Distance between plant and light source DV ~ Rate of photosynthesis

  1. Put pondweed in test tube, add sodium hydrogen carbonate (produces CO2)
  2. Place lamp at a set distance measured with a metre ruler and make sure you are in a dark room

  1. Submerge the test tube in a beaker of water, making sure there is no air at the top.

  2. Start stopwatch and count how many bubbles are released in 1 minute

  3. Or fill the test tube with water and use a capillary tube connected to a gas syringe to collect the oxygen produced in a minute

  4. At the end of the experiment, use the syringe to draw out the gas bubble and measure the length of the bubble with a ruler

  1. Repeat 2 more times with the light source at the same distance and calculate mean
  2. Repeat the whole experiment with the light source at a range of distances

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Control variables

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