Experiment to Show the Rate of Photosynthesis

Experiment to Show the Rate of Photosynthesis

Aim: Experiment to show the rate of photosynthesis when pondweed is

under different life intensities.

Prediction: I predict that the closer the light is to the pondweed the

(or the higher the light intensity) the more oxygen will be produced

until a certain point where the temperature or carbon dioxide levels

will be the limiting factor. The further away the light, the slower

the oxygen bubbles will be produced so the less light the less

photosynthesis will occur which is needed for the plant to make food.

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The rate increases (A) but only to a certain extent. Then they

don't increase any more because of the other limiting factors of the

carbon dioxide levels and temperature.

[IMAGE]

Method:

v Lamp

v Sodium Hydrogen Carbonate

v 1 Meter Ruler

v Water

v Beaker

v Stopwatch

v Pondweed

v Measuring Cylinder

v Scales

* Set up apparatus like above with the light source 5 cm from the

beaker and cut the end of the pondweed.

* Some potassium hydrogen carbonate might have to be added which

provides carbon dioxide for the plant which is needed for

photosynthesis. Then wait for the plant to 'acclimatise'.

* Count the number of bubbles seen in 1 minute which is a way of

measuring the rate of photosynthesis.

* A row of dots on paper while counting can represent each bubble

counted.

* Move the light 10cm away. Wait 2 minutes and then count the bubbles

again.

* Repeat this at 15cm, 20cm then 5cm intervals until the bubbling

stops and repeat each measurement twice to get a more accurate result

and find the average.

Fair Testing:

Changing variable: Light intensity

Variables kept the same:

* Amount of pondweed-

Why: More pondweed, the higher the rate of photosynthesis

How: Weigh pondweed with scales

* Water to absorb heat distance