An Experiment To Investigate The Amount Of O Given Off By Elodea With Varying Concentrations Of NaHCO

increase of light intensity has a small effect.

This graph shows if the temperature of

the plant is raised it may cause the

photosynthesis to speed up, but only to

the point where the light intensity limits

further increase.

Planning-

The experiment is meant to be a fair test. To ensure a fair test the hydrogen carbonate should be the same volume every time, make sure the beaker with the Elodea in is the same distance from the lamp. The weed should be cut at the stem before being put in the beaker. The variables that will be kept constant in the experiment are: water, chlorophyll, light and temperature. The CO varies due to the changes in the NaHCO solution concentrations.

Variables, Affecting Photosynthesis:

- CO

- H O

- Chlorophyll

- Light

- Temperature

Prediction-

The greater the sodium hydrogen carbonate solution concentration, the greater the rate of photosynthesis. The sodium hydrogen carbonate solution concentrations doubles so also the rate of photosynthesis will. When there is less concentration of carbon solution then the bubbles will be quicker and there will be more of them. So photosynthesis is quicker and more oxygen is produced.

Equipment:

- Pond weed (Elodea)

- Beaker

- Sodium hydrogen carbonate solution (NaHCO ) various amounts- 0.000M, 0.025M, 0.050M, 0.100M, 0.200M, 0.400M.

- Light (lamp)

- Stop Clock

- Paper clip

- Measuring cylinder

Diagram-

Method-

- Must follow safety precautions-wear a lab coat.

- Have a measuring cylinder filled at 100cm with NaHCO .

- Get some pondweed and attach a paperclip to it.

- Set up the equipment as in the diagram.

- Go through the different concentrations with the Elodea in.

- Put a thermometer in the beaker to make sure the temperature will be the same.

- Use a lamp near it, which will increase the rate of O bubbles.

- When the Elodea is put in the beaker start the stopwatch and count the bubbles every minute.

- 3 times for each concentration.

Results-

Concentration

Number of bubbles per min

Of NaHCO (m)

1st

2nd

3rd

Average

0

2

2

2

2

0.025

28

24

20

24

0.05

44

28

26

32.6

0.1

36

30

26

30.6

0.2

30

25

32

29

0.4

28

32

26

28.6

Conclusion-

My results support my prediction. My results get faster as there was more sodium hydrogen carbonate used. A few of my results don't follow the others, so they don't support my prediction because they are not as close to the line of best fit; this might be because the concentration of sodium hydrogen carbonate was measured wrong.

Improvements/sources of errors-

The graph curves to the left like it supposed to because the higher the concentration the more amount of bubbles dispersed. The few odd results which aren't near the line of best fit are wrong due to human error either using the wrong amount of concentration or the bubbles might have been counted wrong or the elodea was damaged so didn't produce the right amount of oxygen.

John George 4PJG