Investigate what changes the rate of photosynthesis.

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Investigating the rate of

 Photosynthesis

Aim

To investigate what changes the rate of photosynthesis.

Variables

  For the experiment there are two types of variables, them being dependent and independent. The dependant variable is the condition that will be used to experiment with, in this case the light intensity. The independent variables are those that are either kept constant or change.

  The possible variables for this experiment are:

  • Distance of the lamp
  • Power of light (light bulb)
  • Length of elodea
  • Amount of water
  • Size of test tube
  • Time spent counting

  If the power or the amount of light varies, this will affect the results as I know from scientific knowledge that the more light there is the higher the rate of photosynthesis will be. The length of the elodea will have a dramatic effect on the results, as I know from a past experiment that the bigger the elodea the higher the rate of photosynthesis will be therefore it is crucial to keep it constant. The amount of water will mainly depend on the size on the test tube, but it is important to keep them constant, if they were to change it would affect the results. The main factor of keeping the experiment a fair one is to spend the same time on counting the bubbles each time. If they time spent counting was to be different, this wouldn’t give an accurate set of results, so it is vital to keep that constant.

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  The dependent or the input variable for this experiment is the distance of the lamp from the test tube and elodea. Therefore my experiment will be based on how light intensity affects the rate of photosynthesis.

Apparatus

  • Lamp
  • Elodea
  • Ruler
  • Test tube
  • Test tube holder
  • Stopwatch

Procedure

1) Anchor the pondweed to the bottom of the boiling tube, with the cut end projecting upwards. Three-quarters fill the tube with water.

2) Place the boiling tube x cm from a bench lamp. [measure of the light intensity].

3) Wait ...

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