the amount of carbon dioxide, as this affects the amount of glucose produced.
the light intensity ,as this provides the energy required to split water into hydrogen and oxygen.
And the temperature, as photosynthesis is controlled by enzymes which work faster as temperature increases, but once the optimum temperature is exceeded the enzyme molecules denature stopping the reaction . the law of limiting factors states that the rate of photosynthesis is limited by the factor that is in the shortest or lowest supply . for example the limiting factor at night would be light, in summer it would be carbon dioxide and in winter it would be temperature.
Prediction
I predict in my experiment the rate of photosynthesis will increase as the light intensity does . I predict this due to the fact that as light intensity increases this will provide the chloroplasts with more energy to split the water into hydrogen and oxygen making the reaction faster.
VARIABLES AND FAIR TEST
These are the variables in my experiment :-
Light intensity
Amount of water
Amount of elodea
Amount of heat
How close the lamp is to the elodea
How thick the beaker glass is
The temperature of the water
To make sure my test is fair I wont change any of these variables throughout my experiment, except for light intensity , how close the lamp is to the elodea and the temperature as this will increase as the beaker is moved closer to the lamp.
APPARATUS
The apparatus required for this experiment is :-
A lamp
A stopwatch
Water
Elodea
A metre rule
A beaker
A test tube
A funnel
DIAGRAM
OUTLINE PLAN
In this investigation I am going to use a pond weed called Elodea to see the amount of bubbles (oxygen) that are given off when the light intensity is controlled at different distances.
PRELIMINARY INVESTIGATION
I carried out a preliminary investigation to find out what the best distances are so I can get as accurate and credible results as possible
From my preliminary results I have found out that the most sensible distances to use in my experiment are from 10cm-60cm as these were the distances I got results that can be used .
BLANK TABLE OF RESULTS
This is how I am going to record the results from my experiment
METHOD
1. Collect all the apparatus needed for this experiment (as seen in the apparatus list).
2. Darken the room and make sure the only light in the room is from the light source you are going to be using.
3. Do not start the experiment for another 5 or so minutes till the pond weed (Elodea) gets use to its surroundings .
4. Then set up the apparatus as seen in the picture diagram of the experiment. Make sure the beaker is bigger then the funnel beaker so that the water covers over the top of the funnel beaker
5. Put 2-3 spachelors of Sodium hydrogen carbonate in the water that is in the beaker do not let the sodium hydrogen carbonate touch your hands.
6. The apparatus is now set up. Draw a table of results showing the different distances that you are going to be using so you can record your results as you carry out the experiment.
7. Then using your metre ruler measure out the first distance the Elodea is going to be away from the lamp.
8. Focus the lamps light on the Elodea then using the stopwatch time 1 minute (60 seconds) on the stopwatch for that particular distance.
9. While the stopwatch is going it is advisable to have one person watching the bubbles at eye level and the other person recording the amount of bubbles (it is easier to record it by tally)
10. Then repeat the last 3 steps on the rest of the distances.
11. After you have done all the distances then repeat the test two more times recording your results as you go along. We do this so that your end result is more accurate then if you had just done the test once.
SAFETY
These are the safety rules that should be used while carrying out the experiment
-No running in the laboratory
-When using the Sodium hydrogen carbonate do not touch with your hands use a spachalor .
-Tie back long hair
-Wear safety goggles
RESULTS TABLE
