Page 29 - Ranger SPM 2022 Biology

Biology SPM Chapter 2 Leaf Structure and Function

Aim: To study the effect of temperature on rate of photosynthesis
Hypothesis: As temperature increases, photosynthesis rate also increases until the
optimum temperature
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Materials and apparatus: Water weeds (Hydrilla sp.), 0.2% of sodium hydrogen
carbonate solution, distilled water, 60 W light bulb, 500 ml beaker, water bath,
boiling tube, retort stand, stopwatch and metre rule
Results:

Temperature Total number of gas bubbles Photosynthesis (min )
–1
(°C) released in 5 minutes
10 2 0.4
20 10 2.0
30 25 5.0

35 30 6.0
40 3 0.6
50 0 0.0
Form 5

Rate of photosynthesis (min –1 ) 6 Temperature (ºC)
8

4
2
0

Discussions: 10 20 30 35 40 50
1. 0.2% of sodium hydrogen carbonate solution supplies carbon dioxide to the
water weeds.
2. Based on the results obtained, as the temperature increased (10 °C until 35 °C),
more gas bubbles were released per 5 minutes.
3. From the graph, photosynthesis rate decreased after the optimum temperature
until it became zero at 50 °C. The enzymes involved in photosynthesis were
denatured by the high temperatures.
Conclusion:
Rate of photosynthesis increases as the temperature increases until it reaches its
optimum temperature. The hypothesis was accepted.

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F5 Chapter 2.indd 224 3/29/22 4:35 PM