Carbon dioxide is needed for the equation to work and is needed to create glucose.
Light
Light is needed in photosynthesis to provide the initial energy to start the equation off.
Chlorophyll
Chlorophyll is needed as it us a green pigment which traps the sunlight to help the photosynthesis occur.
Water
Water is needed in this equation to create the glucose.
Controlled variables
We are going to keep all of the variables the same apart from light. New are going to do this by using the same volume of water the same piece of pond weed and use 1 spatula of sodium hydrogen carbonate each time.
Key variables
The one thing I am going to change is light intensity. I will change it by moving a lamp different distances away from the experiment. I will measure the rate of reaction by counting the number of oxygen bubbles given off.
Prediction
I predict that as I move the lamp away from the pondweed the rate of reaction will decrease. This is because light is needed in photosynthesis.
Diagram
Method
Set apparatus up as show in diagram. Put sufficient amount of water into the boiling tube and one spatula of sodium hydrogen carbonate and place the lamp 0cm away from the experiment. Record the amount of oxygen bubbles for 1 minute (use stop clock for accuracy) and repeat this three times. Next move the lamp 10cm away from the experiment and repeat what you did at 0cm away. Do this at the distances; 0cm, 10cm, 20cm, 30cm, 40cm and 50 cm and record result in a table.
Analysis
As the light is moved closer to the experiment the rate of reaction increases and more bubbles are created. This shows that as there is an increase in light the reaction of photosynthesis will be faster. My results prove to me that light is needed to make photosynthesis and the reaction will be speeded up with a higher light intensity.
Evaluation
My results did not show any noticeable anomalous data, which shows it was quite an accurate test.
There are a fair amount of things I could of changed to make the experiment more effective however with no anomalous results and the fact my prediction was correct it seems that my experiment was accurate enough. I did many things to keep my test reliable and all in all it was a success.
Alex Flaherty 11y
