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Compare two methods used to measure the rate of photosynthesis.

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Introduction

Comparing rate of photosynthesis Natalie Loo 12A Aim: To compare two methods used to measure the rate of photosynthesis Diagram: Please see the attached sheet Results: Method 1- Disc Time taken for each disc to rise/s Rate/s-1 1 0 0.0000000 2 345 0.0028985 3 346 0.0028901 4 464 0.0021552 5 502 0.0019920 6 540 0.0018519 7 573 0.0017452 8 574 0.0017422 9 579 0.0017271 10 584 0.0017123 11 585 0.0017094 12 624 0.0016026 13 626 0.0015974 14 680 0.0014706 15 680 0.0014706 16 681 0.0014684 17 681 0.0014684 18 700 0.0014286 19 700 0.0014286 20 782 0.0012788 Method 2- Trail Column of gas/cm Time/s Rate/cm s-1 1 1.60 300 0.0053333 2 1.50 300 0.0050000 3 1.90 300 0.0063333 4 2.00 300 0.0066667 5 1.40 300 0.0046667 ...read more.

Middle

The plant type has an effect on the rate of photosynthesis. Considering the inaccuracy of the techniques, the meniscus might be misread in both methods; the timing for both methods might also be inaccurate. In method 1, the transfer of the discs into the beaker containing 3% sodium bicarbonate solution might not be quick enough. Also, when a number of discs were rising at once, the time recorded for those discs might be slightly inaccurate since I didn't record the results quick enough. To solve these problems, replication of the experiment is needed to increase the accuracy and the reliability of the results. In addition, when the beaker was placed in a well-lit place, the light intensity wasn't constant due to the changing intensity of sunlight. ...read more.

Conclusion

This can guarantee the gas column being measured is the volume of gas given off only by the aquatic plant but nothing else. The mouth of the filter funnel can't touch the bottom of the beaker too, or else water can't be circulated around the set up. Moreover, when the gas is drawn into the capillary, sometimes the meniscus can't be observed therefore results might be inaccurate. In order to overcome this difficulty, the clip needs to be entirely unscrewed with caution for the meniscus to travel along the capillary steadily. Respiration might have some effects on my results of both methods; however, the rate of photosynthesis should have exceeded respiration. In conclusion, there were inaccuracies in both methods but method 2 seemed to be a better method for measuring the rate of photosynthesis. ...read more.

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