Factors affecting the rate of photosynthesis The rate at which photosynthesis occurs is affected by a number of factors, including: Light intensity Carbon dioxide concentration Temperature
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Activity How temperature affects the rate of photosynthesis
Use a water plant such as pondweed (Elodea) for this experiment. Photosynthesis produces oxygen. By counting the number of bubbles coming out from the Elodea stem you can estimate the rate of photosynthesis.
Lamp
Apparatus Three beakers One test tube Glass funnel Elodea Bench lamp
Method 1. Prepare water baths at the following temperatures: 10o
C, 25o C and 40o Gas Water Pondweed
Fig. 9 How temperature affects the rate of photosynthesis.
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2. Set up the experiment as shown in the diagram in Fig. 9. 3. Place the lamp at a fixed distance from the apparatus. 4. Allow the Elodea to adjust to its surroundings for a few minutes before beginning the experiment.
5. Record the number of bubbles produced by the Elodea per minute, at each temperature. Repeat three times and find the average number of bubbles produced per minute.
6. Draw a graph to illustrate your results. Put temperature on the x-axis and number of bubbles on the y-axis. Analyse your data and draw a conclusion about the effect of temperature on the rate of photosynthesis.
