The equation for photosynthesis is:
How photosynthesis works. The process mainly takes place inside the cells of plants, mainly in the leaves. Firstly the plant needs water; this is absorbed from the soil, through the roots and is carried up the stem by water vessels within the veins. Next the plant needs carbon dioxide, this absorbed from the through pores in the leaf known as stomata. Inside cells in the leaves the carbon dioxide is mixed with water to make sugar, but in order for these to be able to mix a source of energy is needed, this energy is gained from sunlight. The sunlight is absorbed from a green pigment in plants called chlorophyll. The chlorophyll is present within the chloroplast of the leaf cells, which the reaction takes place in. Chloroplasts are small green structures found in the cytoplasm of plant cells. Chlorophyll is the substance that gives plants there green colour. It is able to absorb energy from this light. The water molecules are split into hydrogen and oxygen molecules, the oxygen escapes into the atmosphere while the hydrogen is mixed with the carbon dioxide to create sugar.
Prediction: I predict that if there is a higher amount of light intensity on the plant the rate of photosynthesis is going to increase due to there being more energy available to be used to create sugar. As the light gets further away from the plant a weaker source of energy will be reaching the plant and therefore there will be a decrease in the amount of photosynthesis occurring.
Safety: Test should be fairly safe as the only real dangerous features are the lamp is it may become hot and the beakers in case you drop one and the glass smashes.
Fair Testing: To make it fair test we shall do the experiment a number of times for each distance, make sure light source is the exact distance away from the beaker.
Apparatus:
Light source (lamp)
Elodea (aqua plant)
Test tube
Beaker
Stopwatch
Funnel
Sodium hydrogen carbonate
Spatula
Water
Method:
- We shall firstly set up the apparatus as in the diagram below.
- We shall then set the lamp at 10 cm and start the stopwatch.
- We shall then set the lamp at 20cm then 30 and so on up to 50cm.
- We shall do it again to make it fair.
- We shall then record our results.
- And then plot our graph.
Diagram:
By Owen Davies
Results:
Evaluation: During the experiment I found that my prediction was correct in saying that if there is a higher amount of light intensity on the plant the rate of photosynthesis is going to increase, therefore as the light gets further away from the plant a weaker source of energy will be reaching the plant.
Conclusion: To make this experiment better I could have done it more times and I could have used a different plant, this would have helped my results and my graph to show my point. I think the experiment worked fine and it proved my prediction and theory was correct.
By Owen Davies