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Effects of Hydrocarbonate (HCO3) On Photosynthesis.

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Introduction

Effects of Hydrocarbonate (HCO3) On Photosynthesis. In the experiment we placed 2 pieces of Eloda (pondweed) into a syringe. We then filled the syringe with water up to the brim. The nozzle of the syringe was attached to a capillary tube. The barrel of the syringe was then put back on the syringe just enough to not allow any air to get into the apparatus. The syringe was pushed down to push all of the air out of the capillary tube and then pulled back up slowly to form a meniscus. The meniscus was then marked and a lamp placed 8cm away from the apparatus to produce the light needed for the plant to photosynthesise. The meniscus was then measured every 5 minutes for 30 minutes. The process was then repeated but instead of using water in the syringe hydrocarbonate solution was used. These were 0.01, 0.0125, 0.0166, 0.025, 0.5 moles per dm3 . The results we achieved were as a class and are below: Group Becky +Jo Becky +Amy Amy +Andy Conc. Water Water Water Movement meniscus (mm) 5 1 3 46 10 6 9 120 15 19 15 160 20 33 21 220 25 63 27 255 30 113 315 Group Robyn +Becky Group Tewy Keri +Nicola Becky +Robyn Conc. ...read more.

Middle

However this does not work with all of the results. The results achieved for the water prove this. There is a large variation in distances travelled and they do not seem to correspond with the other results. The results the class achieved for the 0.0100M concentration seem to also be anomalous; they do not fit into the pattern. These results were not clarified by the repetition of the concentration therefore we are fully aware of the effects of the 0.0100M concentration. From the results a pattern emerges that the length of the meniscus increases with time. This can be explained by the plant photosynthesising and/or respiring and therefore producing gases. The gases will be released and rise to the top of the syringe and therefore push the meniscus down the capillary tube. The anomalous results we achieved were probably due to mistakes in the experimental procedure and the set up of the experiment. Some of the results may also have been corrupted because of factors that were not considered when setting up the experiment. The first assumption that was made in the experiment that may have affected the results is that we were measuring the effect of the hydrocarbonate in the solution. The movement of the meniscus could have occurred for a number of reasons. We may have been measuring the effect that the lamp had of the solution. ...read more.

Conclusion

The solution would have to have gaseous molecules dissolved in it do that the plant can carry out its process that we are observing therefore some of the gases that the plant produces will therefore be reabsorbed into the solution ready for reuse. This could affect the results if one solution was dissolving more of the gaseous molecules than another's. One observation that I made during the experiment was that in the conical flasks containing the hydrocarbonate solutions sediment was in the bottom. This indicates that the solutions were not exact. This difference in molarity may have affected the results. The sediment also suggests that the solution may been saturated. This means that no more solid can be dissolved in the solution. We have to take into account that the plant is limiting by CO2 concentration. This means that after a certain point the hydrocarbonate in the solution will not increase the rate of photosynthesis. This is because the plant needs a number of substances to carry out photosynthesis and carbon dioxide is one of the main reactants. This means that it will always become a limiting factor. The solution will probably have a steady amount of gaseous molecules dissolved in it but there will never be enough to keep increasing the rate of reaction. This will therefore cause the rate of reaction to level of and continue at a steady pace. 1 ...read more.

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