Our Modified Photosynthesis Experiment – five4fightin~ Aim: To find out if the temperature of the water affects photosynthesis in plants. Hypothesis: The plant in warmer water/higher temperature will have the highest rate of photosynthesis.
Approach: There will be 3 set-ups, including the main control. Each set-ups will have different temperature- Warm (40 Degrees C), Cold (17 Degrees C), and room temperature (37 Degrees C). The calculation of the rate of the photosynthesis is done by using an oxygen sensor to check the oxygen content in the water.
Apparatus: -
1 Data logger 1 Oxygen Sensor 1 Temperature Sensor 3 Beakers 3 Test Tubes 1 Test Tube rack 1 Lamp 1 Stopwatch Bunsen Burner Igniter [To light up Bunsen Burner] Tripod Stand
Materials: -
3 Hydrillas Tap Water Sodium Hydrogen Carbonate Ice Cubes Boiling Water
Variables: Remains constant: Type of Plant, Amount of water, Environment, Amount of Light & Sodium Hydrogen Carbonate. Dependent variable: Temperature of water Measurable variable: Oxygen content of water
Procedure: Your main control set-up should look something like the set-up on the left.
Step 1: In the first set-up, boil water and let it cool to 40 degrees C by stirring the water to let heat escape easily. Temperature of the water can be checked using the temperature sensor and running the MultiLab function in the Nova. Step2: Next, place the hydrilla into a test tube filled with tap water. Make sure the hydrilla is fully submerged in the water. Add 2 small tea spoon of Sodium Hydrogen Carbonate into the test tube with the hydrilla in it. Step 3: Place the test tube into the beaker filled with warm water. This should be labelled as set-up A. Place this set-up under the lighted lamp. Dip the oxygen sensor into the test tube and begin calculating the amount of oxygen it produced. Using the stopwatch, time it to 10 minutes. Step 4: After 10 minutes, record the result. [Note: Do not pour away the warm water; let it cool for the next set-up, that is the main control. Water is precious – save it] Step 5: Next, set-up the 2nd set-up. Put some ice into the beaker with tap water filled in it. Measure the temperature to 17 degrees C. Step 6: Repeat step 2 Step 7: Place test tube into the beaker filled with cool water. This should be labelled as setup B. Place this set-up under the lighted lamp. Dip the oxygen sensor into the test tube and begin calculating the amount of oxygen it produced. Using the stopwatch, time it to 10 minutes Step 8: After 10 minutes, record the result Step 9: Next, set-up the 3rd set-up, which is the main control for the experiment. Using the beaker from set-up 1, measure the temperature of the water. Make sure the temperature is 37 degrees C. Step 10: Repeat step 2 Step 11: Place the test tube into the beaker filled with the water of temperature 37 Degrees C. This should be labelled as set-up C. Place this set-up under the lighted lamp. Dip the oxygen sensor into the test tube and begin calculating the amount of oxygen it produced. Using the stopwatch, time it to 10 minutes Step 12: After 10 minutes, record the result Step 13: Draw conclusion
Conclusion: Yes, temperature does indeed affect the rate of photosynthesis as shown in our experiment whereby photosynthesis occurred at a faster rate at a temperature of 37 Degree Celsius.
Results: Set-up A B C
Temperature Cold Water [170c] Warm Water [400c] Mean Water [370c]
Oxygen Content 7.94 mg/L 6.98 mg/L 8.18 mg/L
Discussion: We came up with the theory that “the plant in warmer water/higher temperature will have the highest rate of photosynthesis� which seems to be correct, but only to a certain extent according to our experiment. The plant in water of room temperature, about 37 Degree Celsius has the highest oxygen content of 8.18 mg/L, and the plant in the warm water of temperature 40 Degree Celsius has the lowest oxygen content of only 6.98 mg/L. At temperatures around 0oC the enzymes stop working as they are inactive and at very high temperatures the enzymes are denatured. An optimum temperature ranging from 28 degrees C to 38 Degrees C is a good temperature range for the highest rate for photosynthesis. Therefore the enzymes in set-up C have denatured causing the plant to not being able to photosynthesize and the oxygen content being lower. As for Set-up A, the oxygen content is still quite acceptable, 7.94 mg/L, higher than the warm water but still lower than the room temperature water which has 0.24mg/L more than it. Since both the stages of photosynthesis require enzyme activity, the condition of the enzymes, be it inactive or denatured due to the temperature, does in the end affect the rate of photosynthesis.
Experimental Errors: The range of temperature we measured could be more chosen with more reasons instead of randomly picking in a range. It would also be better to have more measurements to find the optimum temperature of the plant. Due to the time constraint and everyone mistaking the ph sensor for the oxygen sensor, there was very little time to conduct the experiment. Each set-up had a 'photosynthesis' time of only 3 minutes, which is very short, thus, it might cause the experiment results to be inaccurate. We used the oxygen sensor which was more realizable than counting bubbles but there were still inaccuracies in the experiment. Our results are the average of the oxygen content recorded throughout the experiment. Due to the rush, we were a little not careful and run the MultiLab program before we removed the oxygen sensor from the room temperature water and placed it into the desired set-up. So the final results were a little different. We changed our experiment a little from our previous methods. Instead of using an overturned funnel and a test tube covering the nozzle.
Learning Points: glenn > Not only did I learn how complicated it is to plan such a small and simple experiment but I also learnt more in-depth about the enzymes denaturing and being inactive due to temperature change and because of this, ‘stage 1’ of photosynthesis is not fulfilled and photosynthesis cannot take place fast.