Testing the Effects of Water Temperature on the Cellular Respiration of Yeast
Introduction - Anna
The purpose of this lab is to test whether water temperatures outside of a certain range will increase or decrease the amount of cellular respiration of yeast. The hypothesis statement that will be tested is: if the temperature of water is too far outside of the optimum range for the cellular respiration of yeast cells, then the rate of cellular respiration will decrease. Cellular respiration only occurs under certain conditions, this lab is designed to test the limits of that range, temperature wise. The independent variable in this lab will be the temperature of the water that is used to activate cellular respiration measured in degrees Celsius. The dependent variable is how tall the resulting foam (created by CO2 being released by the yeast cells) is, in centimeters. The control temperature of water for this lab is 32 degrees Celsius; the foam will be measured after six minutes have passed.
The terms “cellular respiration” are key to this experiment. To provide background, cellular respiration is the process heterotrophs use to release usable energy from food when O2 is available. Heterotrophs are organisms that depend on food for energy; unlike autotrophs which produce their own food through photo, or chemosynthesis. Cellular respiration is considered to be the opposite of photosynthesis, it keeps the oxygen and carbon dioxide in the atmosphere balanced. During photosynthesis, CO2 and H2O are taken in and O2 is released as a byproduct. Cellular respiration uses and takes in O2 and in turn releases CO2 and H2O back into the air. The formula used is 6O2+C6H12O6—>6CO2+6H2O+Energy.
There are three basic steps in cellular respiration: glycolysis, the Krebs cycle, and the electron transport chain. For a quick overview; the bulk of the energy that is released from the sugar, in the form of ATP, is during the electron transport chain. Glycolysis does not require O2 to work so it is considered anaerobic. The electron transport chain uses oxygen molecules as the final high-energy electron acceptor. Because of this, it is considered aerobic; as well as the Krebs cycle even though it does not directly need oxygen.
Methodology and Procedure - Pruthvi
The first thing we did was put our goggles on. Then we gathered all of our materials. We gathered four test tubes, one 200mL beaker, a 100mL graduated cylinder, a thermometer, a ruler, two pieces of foil, a dry erase marker, a stopwatch and a test tube holder. After we placed all of our supplies on the table, Anna took a piece of foil and went back to the yeast and sugar station. She molded the foil into a small bowl to hold the sugar. She placed the empty foil bowl on the scale and zeroed it. After that, she carefully placed small scoops of sugar on the foil until the scale read two grams. Then she picked up the foil and took it back to our lab station. She handed me the foil with the sugar and I carefully poured it into the first test tube. Then this step was repeated for the rest of the test tubes. After they all had two grams of sugar in them, we went to the yeast and sugar station again with the second piece of foil. She made the foil into a bowl again; then placed the foil on the scale and zeroed it out. After that, she measured out two grams of yeast on the scale. She took the foil back to the station where she poured the yeast into a test tube with sugar in it. Then she repeated this step for all the test tubes. After they all had two grams of sugar and two grams of yeast, I evenly mixed the yeast and sugar. Then I took the dry erase marker and marked each test tube so I could tell them apart. I took the graduated cylinder to the sink and filled it up with 25mL of lukewarm water. After that I took the water back to the lab station. I took the thermometer and placed it in the water, after a couple of seconds the thermometer read 32°C. I took the thermometer out of the water and placed it on a dry paper towel, and I took the stopwatch out. I cleared the stopwatch and Anna carefully poured the water into the test tube that was marked “C,” which stood for control. When all of the water was in the test tube, I started the stopwatch and marked the current water level. After that, Anna shook the test tube so the yeast and sugar would get wet; then we waited for six minutes. After the six minutes, I measured how much the foam had increased. After I recorded all the data we cleaned the test tube and put it in the holder. Next, I asked Mrs. Bonebrake to heat up some water. After she heated up the water, I carefully poured it in a beaker. Then I poured 25mL of the water into the graduated cylinder. Then, I took the graduated cylinder back to the lab station. Next, I put the thermometer in the graduated cylinder which read 75°C. Then I took out the stopwatch again. We poured the hot water into the test tube that was marked “H,” which represents hot water. Then, I started the stopwatch right away and marked the current water level. I shook the test tube so that the yeast and sugar mixed with the water. Then, Anna and I waited six minutes. I got the ruler and measured how much the foam grew. I recorded the data and cleaned up the lab station. Anna put parafilm on top of the remaining two test tubes and put them away. Then I cleaned up all of the materials that I used.
The next day, I gathered all of the materials and prepped the lab station and got the two test tubs. Anna took the graduated cylinder and filled it up with 25mL of warm water. Then, she took the water to the lab station where I put the thermometer into the graduated cylinder. The thermometer read 50°C. Then we poured the water into the test tube that was marked “O,” which represents other. I started the stopwatch right away and marked the current water level. Then, Anna and I waited six minutes. I got the ruler and measured how much the foam grew. We recorded this data in our notebooks. After that, I filled a bucket with ice. After I got the ice, I waited a couple of minutes so the ice could melt and poured the cold water into the graduated cylinder. I filled the graduated cylinder to 25mL and put in the thermometer. The thermometer read 8°C. Then, we poured the ice water into the test tube that was marked “F” which represented frozen. I then started the stopwatch right away and marked the current water level. I shook the test tube so that all of the yeast and sugar became wet. Then Anna and I waited six minutes and recorded the data. Lastly, we cleaned up our lab station which concluded our experiment.
Data and Results - Anna
Water Temperature (degrees C)
Height of Foam (cm)
Control
32
1
Trial 1
75
5.5
Trial 2
50
5
Trial 3
8
0
As the foam grew, it expanded downwards as well as upwards
In the last trial with 8 degree C water, the yeast stayed in clumps and did not mix well like the trials with warmer water; the yeast clumps floated up and down
Discussion and Analysis - Pruthvi
Our results were different than what we had predicted. We learned lot through the data we collected. We had predicted that if the water temperature was outside the optimal range then the rate of cellular respiration would decrease. Our results showed us that our prediction was both right and wrong. The hot water made the yeast cells grow rapidly and the cold water caused no reaction. The hypothesis relates to the results because the cold water prevented cellular respiration.
During the first trial, we noticed that the foam was expanding upwards and downwards. With this observation we inferred that the water and sugar was being used up since the overall volume of the water had decreased. We also inferred that the foam was using water because as the foam grew, the water level decreased. In the hot water trial, we noticed that the foam grew quickly. I inferred that the hot water was turned into sugar water as the sugar dissolved. Since the water was now sugar water, the yeast cell could easily access the sugar. In the 50°C trial, the foam also grew rapidly. I inferred that heat had played a major role in cellular respiration. In the cold water trial, we saw that there was no growth at all; and the yeast, sugar, and water were not mixing well. I inferred that a little heat is required to start cellular respiration. In the overall experiment, we observed a couple of interesting things. The increase of growth between the control and the 50°C trial was very large. While the increase of growth between the 50°C and the hot water trial was very minimal; the control, 50°C trial, and hot water trial were all evenly spaced out in temperature. With this data I can conclude that there is a maximum point of growth in cellular respiration.
The data about the cold water trial does support our hypothesis. The cold water trial showed us if the water is too cold then cellular respiration is not possible. Our hypothesis says that if the water temperature outside of optimal range then cellular respiration will decrease. Well this trial was very outside of the optimal range of temperature for cellular respiration.
Some possible sources of error could be temperature change. The more different types of container we put the water in, the more likelihood the water temperature would change. To fix this problem I would suggest to make sure the water is constantly monitored.
The hot water trial and 50°C trial both did not support my hypothesis.
My data shows me that temperature has a big effect on cellular respiration.
Some limitations are the room temperature and the amount of time the yeast is exposed.
Some other question I would like to test would be; what is the lowest temperature in which cellular respiration is possible.
Introduction - Anna
The purpose of this lab is to test whether water temperatures outside of a certain range will increase or decrease the amount of cellular respiration of yeast. The hypothesis statement that will be tested is: if the temperature of water is too far outside of the optimum range for the cellular respiration of yeast cells, then the rate of cellular respiration will decrease. Cellular respiration only occurs under certain conditions, this lab is designed to test the limits of that range, temperature wise. The independent variable in this lab will be the temperature of the water that is used to activate cellular respiration measured in degrees Celsius. The dependent variable is how tall the resulting foam (created by CO2 being released by the yeast cells) is, in centimeters. The control temperature of water for this lab is 32 degrees Celsius; the foam will be measured after six minutes have passed.The terms “cellular respiration” are key to this experiment. To provide background, cellular respiration is the process heterotrophs use to release usable energy from food when O2 is available. Heterotrophs are organisms that depend on food for energy; unlike autotrophs which produce their own food through photo, or chemosynthesis. Cellular respiration is considered to be the opposite of photosynthesis, it keeps the oxygen and carbon dioxide in the atmosphere balanced. During photosynthesis, CO2 and H2O are taken in and O2 is released as a byproduct. Cellular respiration uses and takes in O2 and in turn releases CO2 and H2O back into the air. The formula used is 6O2+C6H12O6—>6CO2+6H2O+Energy.
There are three basic steps in cellular respiration: glycolysis, the Krebs cycle, and the electron transport chain. For a quick overview; the bulk of the energy that is released from the sugar, in the form of ATP, is during the electron transport chain. Glycolysis does not require O2 to work so it is considered anaerobic. The electron transport chain uses oxygen molecules as the final high-energy electron acceptor. Because of this, it is considered aerobic; as well as the Krebs cycle even though it does not directly need oxygen.
Methodology and Procedure - Pruthvi
The first thing we did was put our goggles on. Then we gathered all of our materials. We gathered four test tubes, one 200mL beaker, a 100mL graduated cylinder, a thermometer, a ruler, two pieces of foil, a dry erase marker, a stopwatch and a test tube holder. After we placed all of our supplies on the table, Anna took a piece of foil and went back to the yeast and sugar station. She molded the foil into a small bowl to hold the sugar. She placed the empty foil bowl on the scale and zeroed it. After that, she carefully placed small scoops of sugar on the foil until the scale read two grams. Then she picked up the foil and took it back to our lab station. She handed me the foil with the sugar and I carefully poured it into the first test tube. Then this step was repeated for the rest of the test tubes. After they all had two grams of sugar in them, we went to the yeast and sugar station again with the second piece of foil. She made the foil into a bowl again; then placed the foil on the scale and zeroed it out. After that, she measured out two grams of yeast on the scale. She took the foil back to the station where she poured the yeast into a test tube with sugar in it. Then she repeated this step for all the test tubes. After they all had two grams of sugar and two grams of yeast, I evenly mixed the yeast and sugar. Then I took the dry erase marker and marked each test tube so I could tell them apart. I took the graduated cylinder to the sink and filled it up with 25mL of lukewarm water. After that I took the water back to the lab station. I took the thermometer and placed it in the water, after a couple of seconds the thermometer read 32°C. I took the thermometer out of the water and placed it on a dry paper towel, and I took the stopwatch out. I cleared the stopwatch and Anna carefully poured the water into the test tube that was marked “C,” which stood for control. When all of the water was in the test tube, I started the stopwatch and marked the current water level. After that, Anna shook the test tube so the yeast and sugar would get wet; then we waited for six minutes. After the six minutes, I measured how much the foam had increased. After I recorded all the data we cleaned the test tube and put it in the holder. Next, I asked Mrs. Bonebrake to heat up some water. After she heated up the water, I carefully poured it in a beaker. Then I poured 25mL of the water into the graduated cylinder. Then, I took the graduated cylinder back to the lab station. Next, I put the thermometer in the graduated cylinder which read 75°C. Then I took out the stopwatch again. We poured the hot water into the test tube that was marked “H,” which represents hot water. Then, I started the stopwatch right away and marked the current water level. I shook the test tube so that the yeast and sugar mixed with the water. Then, Anna and I waited six minutes. I got the ruler and measured how much the foam grew. I recorded the data and cleaned up the lab station. Anna put parafilm on top of the remaining two test tubes and put them away. Then I cleaned up all of the materials that I used.
The next day, I gathered all of the materials and prepped the lab station and got the two test tubs. Anna took the graduated cylinder and filled it up with 25mL of warm water. Then, she took the water to the lab station where I put the thermometer into the graduated cylinder. The thermometer read 50°C. Then we poured the water into the test tube that was marked “O,” which represents other. I started the stopwatch right away and marked the current water level. Then, Anna and I waited six minutes. I got the ruler and measured how much the foam grew. We recorded this data in our notebooks. After that, I filled a bucket with ice. After I got the ice, I waited a couple of minutes so the ice could melt and poured the cold water into the graduated cylinder. I filled the graduated cylinder to 25mL and put in the thermometer. The thermometer read 8°C. Then, we poured the ice water into the test tube that was marked “F” which represented frozen. I then started the stopwatch right away and marked the current water level. I shook the test tube so that all of the yeast and sugar became wet. Then Anna and I waited six minutes and recorded the data. Lastly, we cleaned up our lab station which concluded our experiment.
Data and Results - Anna
Discussion and Analysis - Pruthvi
Our results were different than what we had predicted. We learned lot through the data we collected. We had predicted that if the water temperature was outside the optimal range then the rate of cellular respiration would decrease. Our results showed us that our prediction was both right and wrong. The hot water made the yeast cells grow rapidly and the cold water caused no reaction. The hypothesis relates to the results because the cold water prevented cellular respiration.
During the first trial, we noticed that the foam was expanding upwards and downwards. With this observation we inferred that the water and sugar was being used up since the overall volume of the water had decreased. We also inferred that the foam was using water because as the foam grew, the water level decreased. In the hot water trial, we noticed that the foam grew quickly. I inferred that the hot water was turned into sugar water as the sugar dissolved. Since the water was now sugar water, the yeast cell could easily access the sugar. In the 50°C trial, the foam also grew rapidly. I inferred that heat had played a major role in cellular respiration. In the cold water trial, we saw that there was no growth at all; and the yeast, sugar, and water were not mixing well. I inferred that a little heat is required to start cellular respiration. In the overall experiment, we observed a couple of interesting things. The increase of growth between the control and the 50°C trial was very large. While the increase of growth between the 50°C and the hot water trial was very minimal; the control, 50°C trial, and hot water trial were all evenly spaced out in temperature. With this data I can conclude that there is a maximum point of growth in cellular respiration.
The data about the cold water trial does support our hypothesis. The cold water trial showed us if the water is too cold then cellular respiration is not possible. Our hypothesis says that if the water temperature outside of optimal range then cellular respiration will decrease. Well this trial was very outside of the optimal range of temperature for cellular respiration.
Some possible sources of error could be temperature change. The more different types of container we put the water in, the more likelihood the water temperature would change. To fix this problem I would suggest to make sure the water is constantly monitored.
The hot water trial and 50°C trial both did not support my hypothesis.
My data shows me that temperature has a big effect on cellular respiration.
Some limitations are the room temperature and the amount of time the yeast is exposed.
Some other question I would like to test would be; what is the lowest temperature in which cellular respiration is possible.