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This experiment involves using a photosynthometer to investigate how temperature affects the rate of photosynthesis in the elodea.

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Introduction

Contents: Page 2 Abstract Page 3 Aim and Introduction Page 8 Prediction Page 9 Preliminary Investigation Page 12 Apparatus and Justification Page 13 Proposed Method Page 15 Analysis of Variables: Page 16 Reliability Page 17 Individual Results Page 18 Class Results Abstract: This experiment involves using a photosynthometer to investigate how temperature affects the rate of photosynthesis in the elodea. Using this apparatus makes it possible to measure the rate of oxygen production by the elodea specimen, while varying the temperature. Bubbles of oxygen molecules are collected in a capillary tube of the apparatus. When a suitable volume of gas has been collected in five minutes, it can be drawn (by a syringe) as bubbles along side the scale and the length of the bubbles measured. The volume of oxygen produced is calculated by multiplying the length of the bubble(s) by pie, which is then multiplied by 0.82 (radius of the tube). The results from this experiment have revealed that an increase in temperature correlates to an increase in the rate of photosynthesis up to 45o C. Beyond this temperature, the rate of photosynthesis starts to decrease in a non uniform manner. Aim: To investigate how temperature affects the rate of photosynthesis in the elodea specimen. Introduction: Photosynthesis is trapping or fixation of carbon dioxide followed by its reduction to carbohydrate (triose phosphate), using hydrogen from water. The necessary energy comes from the absorbed light energy. Light nCo2 + nH2O ======> (CH2O)n + O2 At high light intensities the rate of photosynthesis increases as the temperature is increased over a limited range. At low light intensities, increasing the temperature has a little effect in increasing the rate of photosynthesis1. Research has suggested that photochemical reactions (reactions dependant on light) are generally not affected by temperature. Having said this, research had also stressed that temperature can have a significant impact on the rate of photosynthesis. ...read more.

Middle

Ice b). Water maintained at 45o C c). Water at room temperature (tap water) Proposed Method: * Get hold of the elodea specimen and place it in the boiling tube. * Put the boiling tube in a beaker surrounded by ice. * Ensure the thermometer is standing upright in the beaker. * Note the initial temperature and maintain this throughout the experiment, either by means of adding or reducing the ice content. * Place the electric bench lamp towards the elodea specimen * Allow the elodea specimen to settle for five minutes or so. * On the fifth minute start timing for a further five minutes and count the amount of bubbles observed. Note: The same procedure must be carried out for the other two experiments, only altering the content outside the boiling tube. In order to keep the water temperature at 45o C, it is advised that cool water or some heated water (from the kettle) is added depending on the temperature observed. Prediction: I predict that when the elodea specimen is placed in ice, a few (one or two) oxygen bubbles will be observed, therefore photosynthesis will be limited. When the elodea specimen is placed in water at 45o C, more bubbles will be seen and hence the rate of photosynthesis will increase At room temperature, some bubbles will be seen but much less compared to the 45o C investigation, since the temperature is in between. Results: Ice: Time (minutes) Number of bubbles observed 1 1 2 1 3 3 4 0 5 0 Total: 5 Water maintained at 45o C: Time (minutes) Number of bubbles observed 1 3 2 10 3 12 4 3 5 1 Total: 29 Water at room temperature (tap water): Time (minutes) Number of bubbles observed 1 0 2 2 3 3 4 3 5 3 Total: 11 Discussion: From looking at my results, it appears to be that my prediction is reasonably accurate. ...read more.

Conclusion

The temperature can be maintained by means of adding or removing ice to the water baths. > Due to the limited number of water baths, there may well be the case of sharing a water bath to five others. This means five additional bench lamps would have an impact on my results (as light intensity increases rate of photosynthesis). The lamps may also contribute to the water baths getting hotter than required. Therefore it would be wise to carry out the investigation individually. > When the apparatus are set up, the syringe (on top of the capillary tube) must be pulled to draw the water into the capillary tube. This will remove any air bubbles initially present in the capillary tube and thus leaving no ambiguity. Results: Table: showing the results I obtained during the investigation Temperature (o C) Length of Oxygen bubble (mm) Volume of Oxygen (mm) Rate of photosynthesis (mm3/min) Average rate of photosynthesis (mm3/min) 0.00 1.00 2.01 0.40 0.67 0.00 2.00 4.02 0.80 0.00 2.00 4.02 0.80 10.00 4.00 8.04 1.60 1.87 10.00 6.00 12.06 2.41 10.00 4.00 8.04 1.60 15.00 8.00 16.08 3.22 2.68 15.00 6.00 12.06 2.41 15.00 6.00 12.06 2.41 20.00 8.50 17.09 3.42 3.02 20.00 8.00 16.08 3.22 20.00 6.00 12.06 2.41 25.00 9.00 18.09 3.62 3.49 25.00 9.00 18.09 3.62 25.00 8.00 16.08 3.22 30.00 8.00 16.04 3.21 4.02 30.00 10.00 20.11 4.02 30.00 12.00 24.13 4.83 35.00 12.00 24.13 4.83 5.23 35.00 14.00 28.14 5.63 35.00 13.00 26.13 5.23 40.00 4.50 4.50 1.81 1.81 40.00 5.00 5.00 2.01 40.00 4.00 4.00 1.61 45.00 3.00 6.03 1.21 1.41 45.00 4.00 8.04 1.61 45.00 3.50 7.04 1.41 50.00 2.00 4.02 0.80 0.87 50.00 2.50 5.03 1.01 50.00 2.00 4.02 0.80 55.00 3.00 6.03 1.21 1.07 55.00 3.00 6.03 1.21 55.00 2.00 4.02 0.80 60.00 0.50 1.01 0.20 0.33 60.00 1.00 2.01 0.40 60.00 1.00 2.01 0.40 65.00 1.00 2.01 0.40 0.27 65.00 1.00 2.01 0.40 65.00 0.00 0.00 0.00 Table: Showing the results obtained from the class ...read more.

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