An Experiment to Show the Relation Between Light Intensity and Photosynthesis

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An Experiment to Show the Relation Between Light Intensity and Photosynthesis


Photosynthesis takes places in the leaves of plants, mostly in the

palisade layer of the leaf. Photosynthesis is the plants way of

creating energy for itself(sugar), for growth, repair, storage and

energy production.

The test will be to find out the relationship between light intensity

(voltage) and the rate of photosynthesis. Photosynthesis is:

Carbon dioxide + water + sunlight ---> oxygen + carbohydrate + water


6CO2 + 12H2O + sunlight ---> 6O 2 + C6 H12O 6 + 6H2 O

Oxygen is a product of photosynthesis; therefore we will be measuring

the amount or rate of this product being produced.

Plan and Pulmonary test

Text Box: Prior to the official test I conducted a pulmonary test.

This was so that I could identify any initial problems and work out

how to resolve them. Some problems I encountered where; that the plant

clearly took a few minutes to adjust to its optimum rate of

photosynthesis at the specific light intensity. In order to combat

this problem in the official test I would leave the plant subjected to

the required light intensity for 3 minutes prior to measuring and

recording the volume of oxygen produced. To allow it to

photosynthesise at its optimum rate.

To make it a fair test the plant was sealed off in a box and no other

light was allowed to enter the box, as this could affect the plants

rate of photosynthesis. The wattage was controlled by a transformer

and the pond weed was placed inside the box directly under the light

bulb and surrounded by foil. To give the plant Carbon Dioxide we added

sodium hydrogen carbonate powder (this bubbles to produce Co2

bubbles).To attempt to control the temperature the test tube

containing the pond weed (Canadian) was placed in a water bath- the

water would absorb some of the heat. The plant was subjected to

different wattages of light and the amount of oxygen (rate of
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