Investigate the Factors That Affect the Rate of Respiration in Yeast

Mashrek International School Investigate the Factors that Affect the Rate of Respiration in Yeast. (Temperature) Fawzi El Ansari Biology HL Title: Investigate the Factors that Affect the Rate of Respiration in Yeast. (Temperature) Aim: The aim of this experiment is to investigate the effect of changing the temperature on the rate of respiration in yeast. This will be done by placing equal amounts of yeast in each beaker that contains the same pH solution. Each beaker will be mixed with glucose solution and then will be placed at a different temperature in which the amount of CO2 produced will be measured every one minute.

Rationale: As we all know, respiration is a process that takes place in all living organisms where it converts sugar, taken in by the organism into energy. Its formula is C6H12O6+ 6O2—-> 6CO2+ 6H2O + ATP. The yeast in this experiment will have to respire an-aerobically because there will be an absence of oxygen. The higher the temperature the more kinetic energy there is. When there is more kinetic energy, the molecules will move faster thus colliding with each other more often, so therefore there will be a higher percentage chance of an enzyme colliding with its substrate successfully.

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However, once optimum temperature is reached, the substrate can no longer bind to the active site, and the reaction will no longer take place. Here, the enzyme will begin to deform and the hydrogen bonds formed between amino acids will break, and the yeast enzyme will begin to denature. Hypothesis: If the temperature increases, then the rate of the reaction will increase and the rate of CO2 will increase until it reaches its maximum temperature and then begins to denature. Variables: Independent Variable: Temperature of yeast solution Dependent Variable: Rate at which CO2 is released by time

Controls: pH of solution kept at 7 Type of concentration of glucose sugar used Time set of experiment for all trials is 10 minutes Mass of yeast set at 4 grams. Mass of glucose set at 10 grams Materials: 1) Yeast 2) Glucose sugar 3) Stop Watch 4) Test Tubes 5) Thermometer 6) Beakers 250mL 7) Electric Water Bath 8) Distilled Water 100 mL 9) Glass Rod 10) Digital Balance 11) Measuring Cylinder 15mL Procedure: 1) Set the apparatus as shown in the diagram 2) Set the electric water bath to a temperature of 35 degrees Celsius 3) Place 10 grams of glucose powder into a beaker and add 100 mL of water.

Swirl gently to mix. 4) Pour 20 cc of glucose solution into a clonical flask and add 4 grams of yeast to it. 5) Replace the bung in the flask ensuring an air tight seal. Fill the graduated tube with water and invert carefully into the beaker of water. Do not place over the end of the delivery tube. 6) Immediately position the graduated tube over the end of the delivery tube and measure the volume of CO2 collected every 1 minute for 10 minutes. 7) Repeat the experiment using different temperatures of water, 40 C, 50 C, and 60C. 8) This is how the variables were calculated: ) The independent variable (the temperature of yeast solution) was changed every time by setting different temperatures on the electric water bath. 2) The rate of CO2 was measured by calculating the amount released from the graduated tube every one minute for ten minutes with the graduated tube being attached to the yeast and glucose solution. 3) The pH of the solution was kept at 7. 4) The same type of glucose sugar powder was used for all trials. 5) The time set for all the experiments was ten minutes and was calculated using a stopwatch. ) The mass of the yeast was measured at 4 grams for each trial using a digital balance for each trial. 7) The mass of glucose powder was measured at 10 grams using a digital balance for each. trial Calculate the rate of CO2 released from each trial and present your data. Safety Measures: * Wear Gloves At All Times * Be careful when handling items that are related to the water bath, as the water might be very hot. Data Collection: Table 1: Volume of CO2 produced from yeast during respiration at different temperatures. | Volume of CO2 produced from yeast during respiration at temperatures/mL (+/-0. )| Time/min. (+/- 1)| 35/C| 40/C| 50/C| 60/C| 0| 0. 0| 0. 0| 0. 0| 0. 0| 1| 0. 0| 8. 0| 28. 0| 10. 0| 2| 0. 0| 16. 0| 40. 0| 14. 0| 3| 0. 0| 34. 0| 54. 0| 14. 0| 4| 0. 0| 50. 0| 70. 0| 14. 0| 5| 0. 0| 64. 0| 80. 0| 14. 0| 6| 10. 0| 80. 0| 92. 0| 14. 0| 7| 10. 0| 98. 0| 106. 0| 14. 0| 8| 10. 0| 110. 0| 108. 0| 14. 0| 9| 18. 0| 130. 0| 108. 0| 14. 0| 10| 20. 0| 144. 0| 110. 0| 14. 0| Observations: During the experiment, bubbles were present from the water in the electric water baths that were set at temperatures of 50 degrees Celsius and 60 degrees Celsius.

This is because the water has passed its boiling point and began to boil. The glucose powder had a white color. The yeast powder had a mild yellow color. When the glucose solution was mixed with water, it gave a clear color. When glucose solution was mixed with the yeast, it produced a murky yellow color. Bubbles also arose when CO2 was being lost in the experiment under each desired temperature. Graph 1: Volume of CO2 produced from different temperatures and the time recorded each minute. Data Processing:

Table 2: Slope of different Temperatures of the measured results of the volume of CO2 produced from yeast during respiration. Different Temperatures/C(+/- 1)| Rate/cc/min. (+/-0. 01)| 35| 2. 11| 40| 14. 98| 50| 10. 91| 60| 0. 78| Graph 2: Slopes of different Temperatures of the measured results from the volume of CO2 produced from the respiration of yeast. y-axis x-axis Calculations: The slope was calculated on Microsoft Excel. The data collected for each volume was the input of the y-axis and the time was the input for the x-axis on the auto slope option on Excel.

Conclusion and Evaluation: In conclusion the results show the exact process of respiration on yeast. The electric water bath set at 35 degrees Celsius. Here the temperature is slowly increasing which is resulting in a gradual increase of enzyme activity. The increase in temperature of the enzyme and substrate will result in molecular collision to fit in the enzyme to become an enzyme substrate complex which leads to a faster product. At 40 degrees Celsius, respiration on yeast showed the most progress as there were more enzymes colliding and attaching with its specific substrate.

At 50 degrees Celsius the enzymes were rapidly moving at an even faster pace than at the 40 degrees Celsius, however once it reached 7 minutes, there were minimal enzymes left to fit with the substrates and the enzyme substrate complex products began to decrease. At 60 degrees Celsius, it is very obvious that the temperature has exceeded its optimum temperature. Here the rate of the enzyme activity drops rapidly as noticed in the “rate” graph because the enzymes have become denatured. These results are consistent with my hypothesis.

In my hypothesis, I stated that if the temperature increases, then the rate of the reaction will increase and the rate of CO2 will increase until it reaches its maximum temperature and then begins to denature. This has occurred in the experiment as described above. The reaction increased as the temperature increased from 35 degrees to 40 degrees to 50 degrees until it surpassed its optimum temperature and began to denature at 60 degrees Celsius. My results have been compared with a literature value obtained from the internet explorer and are very similar. Many errors occurred during this experiment.

One error that might have occurred is that when setting the electric water bath to the desired temperature, for some reason it would not reach that temperature exactly. At one electric bath that I had set to 40 degrees Celsius, when measuring it with a thermometer to make sure, the thermometer read 43 degrees Celsius, however I recorded my results as 40 degrees Celsius. This probably did not have a great affect on my experiment, however if it did have an effect, then my results for the amount of CO2 that has dispersed for the 40 degrees Celsius might differ a bit but overall it does not affect the result of my hypothesis.

A second error that might have occurred is that when placing the bung on the flask, to ensure an air tight seal, the bung might have let some air into the flask. The bung contained a hole at the top, and although it was covered with Vaseline, to ensure an air tight seal, some air might have seeped through it. This might have changed some of my results significantly when recording the amount of CO2 that has been produced from the different temperatures used in the experiment.

A third error that might have occurred is that time might not have been measured accurately due to distractions. This might have had a minimal effect on my experiment as not the right amount of CO2 produced was recorded at the correct time. A fourth error that might have occurred is that not the correct volume of CO2 produced was recorded correctly. This is related to the error with time as the units on the graduated tube were small, so maybe not the exact volume of CO2 produced was measured at the correct time.

Every experiment contains errors and all errors have a way of being improved. The first error of the electric bath problem can be fixed in two ways. The first method of improving it is to record your results based on the temperature recorded with a thermometer and not on the temperature set on the electric water bath as a thermometer will be more reliable. A second method is to check if this problem is the same on other water baths as the electric water bath you are using is not functioning properly.

It would be advised to ask a lab technician to help you in this problem. To improve the second error, it would be advised to place as much Vaseline as possible in the area of the hole and around the bung. Also place your thumb on top of the bung and placing pressure on it will help ensure an air tight seal and will also ensure better results. The improvements for the third and fourth error would be to focus on the time and maybe have a partner help you in reading the volume on the graduated cylinder as the CO2 is produced.

I do not believe I need to suggest a new hypothesis as the errors where minimal and in the end my results due make sense and are almost the same as the literature value. This is investigation could be taken further by using different types of glucose sugar in the experiment instead of one kind. By using different types of sugar, such as brown sugar etc, a more intriguing experiment will be preformed and the rate of respiration under different temperatures and different types of sugar can be recorded and compared. Literature value source- http://www. biotopics. co. uk/humans/respro. html


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