(no subject)
Cellular Respiration
Amy Rayo
Period 4
November 2, 2006
Cellular Respiration
Objective:
The objectives of this lab were to understand respiration, dormancy, and germination, how a respirometer works in terms of gas laws, the general processes of metabolism in living organisms, how the rate of cellular respiration relates to the amount of activity in a cell, how the rate of cellular respiration relates to the amount of activity in a cell. In addition, we should be able to calculate the rate of cell respiration fro experimental data, relate gas production to respiration rate, test the rate of cellular respiration in germinating versus nongerminated seeds in a controlled experiment, and finally how to test the effect of temperature on the rate of cell respiration in germinating versus non germinated seeds in a controlled experiment.
Background Information:
Aerobic Cellular respiration is the release of energy from organic compounds by metabolic chemical oxidation in the mitochondria within each cell. Cellular respiration involves a series of enzyme-mediated reactions. The equation below shows the complete oxidation of glucose. Oxygen is required for this energy-releasing process to occur.
C6H12O6 + 6O2 -----> 6 CO2 + 6 H2O + 686 kilocalories of energy / mole of glucose oxidized
By measuring the relative volume of O2 consumed by germinating and non-germinating, the rate of cellular respiration could be measured. A respirometer is a device used to measure the rate of respiration of a living organism by measuring its rate of exchange of oxygen and carbon dioxide. The apparatus works based on the principle of gas laws.
PV =nRT
This law implies that if temperature and pressure are kept constant, then the volume of the gas is directly proportional to the number of molecules of gas. Also that if the temperature and volume remain constant, then the pressure of the gas changes in direct proportion to the number of molecules of gas present. A simple respirometer designed to measure oxygen uptake or CO2 release consists of a sealed container with the living specimen together with cotton wads soaked with potassium hydroxide to absorb the carbon dioxide given off during respiration.
CO2 + 2 KOH ----> K2CO3 + H2O
Since the carbon dioxide is being removed, the change in the volume of gas in the respirometer will be directly related to the amount of oxygen consumed. In the experimental apparatus if water temperature and volume remain constant, the water will move toward the region of lower pressure. During respiration, oxygen will be consumed. Its volume will be reduced, because the carbon dioxide produced is being converted to a solid. The net result is a decrease in gas volume within the tube, and a related decrease in pressure in the tube. The vial with glass beads alone will permit detection of any changes in volume due to atmospheric pressure changes or temperature changes.
Hypothesis:
If the seeds were to be in warm conditions, then the rate of oxygen will be higher at room temperature than at 10 degree Celsius. Also, since the rate of cellular respiration increases while in optimal conditions, then a germinating seed will produce more oxygen than a nongerminating seed
Materials:
3 respirator tube
A tray of water at room temperature
Wads of Cotton dipped in Potassium Hydroxide
Beads
Germinating Peas
Non-germinating Peas
100 mL Graduated Cylinder
Procedures:
Prepare a room-temperature bath (approx. 25 degrees Celsius) and a cold-water bath (approx. 10 degrees Celsius).
Find the volume of 25 germinating peas by filling a 100mL graduated cylinder 50mL and measuring the displaced water.
Fill the graduated cylinder with 50mL water again and drop 25 non-germinating peas and add enough glass beads to attain an equal volume to the germinating peas.
Using the same procedure as in the previous two steps, find out how many glass beads are required to attain the same volume as the 25 germinating peas.
To assemble 3 respirometer, obtain 3 vials, each with an attached stopper and pipette. Number the vials. Place a small wad of absorbent cotton in the bottom of each vial and, using a dropper, saturate the cotton with 15% KOH (potassium hydroxide). It is important that the same amount of KOH be used for each respirometer.
Place a small wad of dry, nonabsorbent cotton on top of the saturated cotton.
Place the first set of germinating peas, dry peas & beads, and glass beads in the three vials, respectively. Insert the stopper with the calibrated pipette. Place a weighted collar on each end of the vial. Several washers around the pipette make good weights.
Make a sling of masking tape attached to each side of the water baths. This will hold the ends of the pipettes out of the water during an equilibration period of 7 minutes. Vials 1, 2, and 3 should be in the room temperature bath.
After 7 min., put all six set-ups entirely into the water. A little water should enter the pipettes and then stop. If the water continues to enter the pipette, check for leaks in the respirometer.
Allow the respirometers to equilibrate for 3 more minutes and then record the initial position of the water in each pipette to the nearest 0.01mL (time 0). Check the temperature in both baths and record. Record the water level in the six pipettes every 5 minutes for 20 minutes.
Obtain data for the 10ºC baths from the other group who have followed the same procedures in 10ºC water.
Data:
Table 5.1: Measurement of O2 Consumption by Soaked and Dry Pea Seeds at Room Temperature and 10°C using volumetric methods
Temp
(°C) Time
(min) Beads alone Germinating Peas Dry Peas and Beads
Reading at time X Diff.* Reading at time X Diff.* Corrected
Diff. D Reading at time X Diff.* Corrected
Diff. D
Room
25°C 0 8.50 6.90 8.40
5 8.40 0.10 4.90 2.00 1.90 8.10 0.30 0.20
10 8.30 0.20 2.50 4.40 4.20 7.90 0.50 0.30
15 8.20 0.30 0.10 6.80 6.50 7.70 0.70 0.40
20 8.15 0.35 -2.10 9.00 8.65 7.60 0.80 0.45
With Ice
10°C 0 8.30 7.50 8.50
5 8.30 0.00 6.35 1.15 1.15 8.45 0.05 0.05
10 8.25 0.05 5.60 1.90 1.85 8.40 0.10 0.05
15 8.25 0.05 4.80 2.70 2.65 8.35 0.15 0.10
20 8.20 0.10 4.10 3.40 3.30 8.30 0.20 0.10
* Difference = (initial reading at time 0) - (reading at time X)
D Corrected Difference = (initial pea seed reading at time 0 - pea seed reading at time X) - (initial bead reading at time 0 - bead reading at time X)
Analysis of Results:
In this investigation, you are investigating both the effect of germination versus nongermination and warm temperature versus cold temperature on respiration rate. Identify the hypothesis being tested in this activity?
If the seeds were to be in warm conditions, then the rate of oxygen will be higher at room temperature than at 10 degree Celsius. Also, since the rate of cellular respiration increases while in optimal conditions, then a germinating seed will produce more oxygen than a nongerminating seed
This activity uses a number of controls. Identify at least three of the controls, and describe the purpose of each control.
Number of peas held constant
Same volumes used for peas, peas/beads, or beads
Water baths held at constant temperature
Respirometers and pipettes used are the same for all treatments
Wads of cotton are the same size
Volume of KOH is the same in each tube
Equilibration times are the same for all respirometers.
Graph the results from the corrected difference column for the germinating peas and dry peas at both room temperature and 100C.
a. What is the independent variable? Time (in minutes)
b. What is the dependent variable? Oxygen consumed (mL)
Describe and explain the relationship between the amount of oxygen consumed and time.
At the warmer temperature, room temperature, the amount of oxygen consumed was the highest due to how these were the seed’s optimal conditions. On the other hand, the dried peas were deprived of nutrients, hence a deviation from optimal conditions, as a result their rate of cellular respiration was slower. There is a direct relationship between the amount of time passed and the amount of oxygen consumed.
From the slope of the four lines on the graph, determine the rate of oxygen consumption of germinating and dry peas during the experiments at room temperature and 10ºC. Recall that rate = deltaY/delta X.?
Why is it necessary to correct the readings from the peas with the readings from the beads?
Due to how the beads served as a control , which allows accounting for changes that we are unable to control, such as the environment. =
Explain the effect of germination (versus non-germination) on peas seed respiration.
The germinating seeds are growing, hence they must be using cellular respiration in order to acquire the nutrients needed to grow. The rate of cellular respiration was also higher in the germinating seeds due to the same reason.
Graph 5.2 is a sample graph of possible data obtained for oxygen consumption by germinating peas up to 8ºC. Draw in predicted results through 45ºC. Explain your prediction.
As the temperature increased, the enzymes denatured causing a deficiency in germination.
What is the purpose of KOH in this experiment?
The function of the KOH is to react with the carbon dioxide and produce a product of cellular respiration. By having the Carbon Dioxide converted to a solid, the Carbon Dioxide will have less influence in the volume readings. As a result, any change in volume of the gas in the respirometer is due to the decrease in the amount of oxygen consumed by the respiring cells.
CO2 + 2 KOH ----> K2CO3 + H2O
Why did the vial have to be completely sealed around the stopper?
To avoid any outside interference to come inside the vial, and to keep the water in.
If you used the same experimental design to compare the rates of respiration of a 25 g. reptile and a 25 g. mammal, at 100C, what results would you expect? Explain your reasoning.
Cellular Respiration rate would be higher in the mammal since they are warm-blooded. Thus the mammal would consume more oxygen at 10ºC.
If respiration in a small mammal were studied at both room temperature (21ºC) and 10ºC, what results would you predict? Explain your reasoning.
It would be higher at the colder temperature due to how the animal would keep its body temperature stable, and in order to achieve that a higher respiration rate is needed. . The results would reveal higher respiration rate and higher oxygen consumption than the warmer temperature.
Explain why water moved into the respirometer pipettes.
As the seeds respired (underwent cellular respiration) they consumed oxygen and gave off carbon dioxide. The carbon dioxide reacted with the KOH to form a solid of negligible volume. Therefore there was a decrease in the volume of gas in the vial and in the pipette. Since the pipette tip was open to the water bath, water moved into the pipette, occupying the space left when the oxygen was consumed by the germinating seeds and the carbon dioxide was removed from the air by the KOH.
Design an experiment to examine the rates of cellular respiration in peas that have been germinating for 0, 24, 48, and 72, hours. What results would you expect? Why?
Following the same protocol as outlined in this lab. We can determine the optimal temperature of the water for this experiment. Set up respirometers which have one of the following:
seeds that have not begun to germinate
seeds that have been germinating for 24 hours
seeds that have been germinating for 48 hours
seeds that have been germinating for 72 hour
One would expect that there would be no oxygen consumed by the seeds that had not begun to germinate. The most oxygen would be consumed by the seeds that had been germinating for the longest period of time. The other two sets of seeds would consume intermediate amounts of oxygen, with more being consumed in the seeds that had been germinating longer.
These results would be expected because non-germinating seeds aren’t performing cellular respiration at a rate measurable with this type of apparatus. As seeds germinate, more and more cells are present. In each cell, oxygen is needed as the final electron acceptor in the electron transport system. Therefore, the longer the seeds have been germinating, the more cells there are respiring, and the more oxygen will be consumed.
Conclusion
The purpose of the experiment was to observe the rate of cellular respiration by relating it directly to the rate of oxygen consumption. Furthermore, the effect of temperature on rate of cellular respiration was investigated. The rate of cellular respiration should be optimal for room temperature and thus should occur best in germinating seeds at room temperature. Respirometers were set up with germinating peas, dry peas & beads, and beads alone, equal volume of each. The KOH absorbent cotton was added to consume any CO2 produced during cellular respiration. The beads served as control to account for atmospheric changes. After being equilibrated, the respirators were submerged in the water. As expected, the results of the data revealed the most oxygen consumption to have occurred in germinating seeds at room temperature (0.4293 mL O2 / min). This is because the rate of cellular respiration is highest under these conditions. At 10ºC the rate of respiration is significantly lower (0.1733 mL O2 / min) relative to room temperature. Germinating peas undergo cellular respiration, while in dry peas the cellular respiration is minimal. At room temperature the dry peas rate of oxygen consumption was (0.0253 mL O2 / min), as expected. At 10ºC the rate was even lower (0.0057 mL O2 / min), since almost no cellular respiration occurred at such low temperature in dry peas. The results revealed the relation between gas production and respiration rates as well as demonstrated the effect of temperature on the rate of cellular respiration. Sources of errors include the validity of the seals, since if there could have been a leak. Also, the absorbent cotton balls that were used for the KOH could have been too saturated. Another source of error could be at the temperature of the water baths. If a close eye wasn’t kept on the temperature, the ten degree Celsius would have fallen in degrees. Further research could be conducted using reptiles vs. mammals, and observing the rate of respiration in live animals.
Amy Rayo
Period 4
November 2, 2006
Cellular Respiration
Objective:
The objectives of this lab were to understand respiration, dormancy, and germination, how a respirometer works in terms of gas laws, the general processes of metabolism in living organisms, how the rate of cellular respiration relates to the amount of activity in a cell, how the rate of cellular respiration relates to the amount of activity in a cell. In addition, we should be able to calculate the rate of cell respiration fro experimental data, relate gas production to respiration rate, test the rate of cellular respiration in germinating versus nongerminated seeds in a controlled experiment, and finally how to test the effect of temperature on the rate of cell respiration in germinating versus non germinated seeds in a controlled experiment.
Background Information:
Aerobic Cellular respiration is the release of energy from organic compounds by metabolic chemical oxidation in the mitochondria within each cell. Cellular respiration involves a series of enzyme-mediated reactions. The equation below shows the complete oxidation of glucose. Oxygen is required for this energy-releasing process to occur.
C6H12O6 + 6O2 -----> 6 CO2 + 6 H2O + 686 kilocalories of energy / mole of glucose oxidized
By measuring the relative volume of O2 consumed by germinating and non-germinating, the rate of cellular respiration could be measured. A respirometer is a device used to measure the rate of respiration of a living organism by measuring its rate of exchange of oxygen and carbon dioxide. The apparatus works based on the principle of gas laws.
PV =nRT
This law implies that if temperature and pressure are kept constant, then the volume of the gas is directly proportional to the number of molecules of gas. Also that if the temperature and volume remain constant, then the pressure of the gas changes in direct proportion to the number of molecules of gas present. A simple respirometer designed to measure oxygen uptake or CO2 release consists of a sealed container with the living specimen together with cotton wads soaked with potassium hydroxide to absorb the carbon dioxide given off during respiration.
CO2 + 2 KOH ----> K2CO3 + H2O
Since the carbon dioxide is being removed, the change in the volume of gas in the respirometer will be directly related to the amount of oxygen consumed. In the experimental apparatus if water temperature and volume remain constant, the water will move toward the region of lower pressure. During respiration, oxygen will be consumed. Its volume will be reduced, because the carbon dioxide produced is being converted to a solid. The net result is a decrease in gas volume within the tube, and a related decrease in pressure in the tube. The vial with glass beads alone will permit detection of any changes in volume due to atmospheric pressure changes or temperature changes.
Hypothesis:
If the seeds were to be in warm conditions, then the rate of oxygen will be higher at room temperature than at 10 degree Celsius. Also, since the rate of cellular respiration increases while in optimal conditions, then a germinating seed will produce more oxygen than a nongerminating seed
Materials:
3 respirator tube
A tray of water at room temperature
Wads of Cotton dipped in Potassium Hydroxide
Beads
Germinating Peas
Non-germinating Peas
100 mL Graduated Cylinder
Procedures:
Prepare a room-temperature bath (approx. 25 degrees Celsius) and a cold-water bath (approx. 10 degrees Celsius).
Find the volume of 25 germinating peas by filling a 100mL graduated cylinder 50mL and measuring the displaced water.
Fill the graduated cylinder with 50mL water again and drop 25 non-germinating peas and add enough glass beads to attain an equal volume to the germinating peas.
Using the same procedure as in the previous two steps, find out how many glass beads are required to attain the same volume as the 25 germinating peas.
To assemble 3 respirometer, obtain 3 vials, each with an attached stopper and pipette. Number the vials. Place a small wad of absorbent cotton in the bottom of each vial and, using a dropper, saturate the cotton with 15% KOH (potassium hydroxide). It is important that the same amount of KOH be used for each respirometer.
Place a small wad of dry, nonabsorbent cotton on top of the saturated cotton.
Place the first set of germinating peas, dry peas & beads, and glass beads in the three vials, respectively. Insert the stopper with the calibrated pipette. Place a weighted collar on each end of the vial. Several washers around the pipette make good weights.
Make a sling of masking tape attached to each side of the water baths. This will hold the ends of the pipettes out of the water during an equilibration period of 7 minutes. Vials 1, 2, and 3 should be in the room temperature bath.
After 7 min., put all six set-ups entirely into the water. A little water should enter the pipettes and then stop. If the water continues to enter the pipette, check for leaks in the respirometer.
Allow the respirometers to equilibrate for 3 more minutes and then record the initial position of the water in each pipette to the nearest 0.01mL (time 0). Check the temperature in both baths and record. Record the water level in the six pipettes every 5 minutes for 20 minutes.
Obtain data for the 10ºC baths from the other group who have followed the same procedures in 10ºC water.
Data:
Table 5.1: Measurement of O2 Consumption by Soaked and Dry Pea Seeds at Room Temperature and 10°C using volumetric methods
Temp
(°C) Time
(min) Beads alone Germinating Peas Dry Peas and Beads
Reading at time X Diff.* Reading at time X Diff.* Corrected
Diff. D Reading at time X Diff.* Corrected
Diff. D
Room
25°C 0 8.50 6.90 8.40
5 8.40 0.10 4.90 2.00 1.90 8.10 0.30 0.20
10 8.30 0.20 2.50 4.40 4.20 7.90 0.50 0.30
15 8.20 0.30 0.10 6.80 6.50 7.70 0.70 0.40
20 8.15 0.35 -2.10 9.00 8.65 7.60 0.80 0.45
With Ice
10°C 0 8.30 7.50 8.50
5 8.30 0.00 6.35 1.15 1.15 8.45 0.05 0.05
10 8.25 0.05 5.60 1.90 1.85 8.40 0.10 0.05
15 8.25 0.05 4.80 2.70 2.65 8.35 0.15 0.10
20 8.20 0.10 4.10 3.40 3.30 8.30 0.20 0.10
* Difference = (initial reading at time 0) - (reading at time X)
D Corrected Difference = (initial pea seed reading at time 0 - pea seed reading at time X) - (initial bead reading at time 0 - bead reading at time X)
Analysis of Results:
In this investigation, you are investigating both the effect of germination versus nongermination and warm temperature versus cold temperature on respiration rate. Identify the hypothesis being tested in this activity?
If the seeds were to be in warm conditions, then the rate of oxygen will be higher at room temperature than at 10 degree Celsius. Also, since the rate of cellular respiration increases while in optimal conditions, then a germinating seed will produce more oxygen than a nongerminating seed
This activity uses a number of controls. Identify at least three of the controls, and describe the purpose of each control.
Number of peas held constant
Same volumes used for peas, peas/beads, or beads
Water baths held at constant temperature
Respirometers and pipettes used are the same for all treatments
Wads of cotton are the same size
Volume of KOH is the same in each tube
Equilibration times are the same for all respirometers.
Graph the results from the corrected difference column for the germinating peas and dry peas at both room temperature and 100C.
a. What is the independent variable? Time (in minutes)
b. What is the dependent variable? Oxygen consumed (mL)
Describe and explain the relationship between the amount of oxygen consumed and time.
At the warmer temperature, room temperature, the amount of oxygen consumed was the highest due to how these were the seed’s optimal conditions. On the other hand, the dried peas were deprived of nutrients, hence a deviation from optimal conditions, as a result their rate of cellular respiration was slower. There is a direct relationship between the amount of time passed and the amount of oxygen consumed.
From the slope of the four lines on the graph, determine the rate of oxygen consumption of germinating and dry peas during the experiments at room temperature and 10ºC. Recall that rate = deltaY/delta X.?
Why is it necessary to correct the readings from the peas with the readings from the beads?
Due to how the beads served as a control , which allows accounting for changes that we are unable to control, such as the environment. =
Explain the effect of germination (versus non-germination) on peas seed respiration.
The germinating seeds are growing, hence they must be using cellular respiration in order to acquire the nutrients needed to grow. The rate of cellular respiration was also higher in the germinating seeds due to the same reason.
Graph 5.2 is a sample graph of possible data obtained for oxygen consumption by germinating peas up to 8ºC. Draw in predicted results through 45ºC. Explain your prediction.
As the temperature increased, the enzymes denatured causing a deficiency in germination.
What is the purpose of KOH in this experiment?
The function of the KOH is to react with the carbon dioxide and produce a product of cellular respiration. By having the Carbon Dioxide converted to a solid, the Carbon Dioxide will have less influence in the volume readings. As a result, any change in volume of the gas in the respirometer is due to the decrease in the amount of oxygen consumed by the respiring cells.
CO2 + 2 KOH ----> K2CO3 + H2O
Why did the vial have to be completely sealed around the stopper?
To avoid any outside interference to come inside the vial, and to keep the water in.
If you used the same experimental design to compare the rates of respiration of a 25 g. reptile and a 25 g. mammal, at 100C, what results would you expect? Explain your reasoning.
Cellular Respiration rate would be higher in the mammal since they are warm-blooded. Thus the mammal would consume more oxygen at 10ºC.
If respiration in a small mammal were studied at both room temperature (21ºC) and 10ºC, what results would you predict? Explain your reasoning.
It would be higher at the colder temperature due to how the animal would keep its body temperature stable, and in order to achieve that a higher respiration rate is needed. . The results would reveal higher respiration rate and higher oxygen consumption than the warmer temperature.
Explain why water moved into the respirometer pipettes.
As the seeds respired (underwent cellular respiration) they consumed oxygen and gave off carbon dioxide. The carbon dioxide reacted with the KOH to form a solid of negligible volume. Therefore there was a decrease in the volume of gas in the vial and in the pipette. Since the pipette tip was open to the water bath, water moved into the pipette, occupying the space left when the oxygen was consumed by the germinating seeds and the carbon dioxide was removed from the air by the KOH.
Design an experiment to examine the rates of cellular respiration in peas that have been germinating for 0, 24, 48, and 72, hours. What results would you expect? Why?
Following the same protocol as outlined in this lab. We can determine the optimal temperature of the water for this experiment. Set up respirometers which have one of the following:
seeds that have not begun to germinate
seeds that have been germinating for 24 hours
seeds that have been germinating for 48 hours
seeds that have been germinating for 72 hour
One would expect that there would be no oxygen consumed by the seeds that had not begun to germinate. The most oxygen would be consumed by the seeds that had been germinating for the longest period of time. The other two sets of seeds would consume intermediate amounts of oxygen, with more being consumed in the seeds that had been germinating longer.
These results would be expected because non-germinating seeds aren’t performing cellular respiration at a rate measurable with this type of apparatus. As seeds germinate, more and more cells are present. In each cell, oxygen is needed as the final electron acceptor in the electron transport system. Therefore, the longer the seeds have been germinating, the more cells there are respiring, and the more oxygen will be consumed.
Conclusion
The purpose of the experiment was to observe the rate of cellular respiration by relating it directly to the rate of oxygen consumption. Furthermore, the effect of temperature on rate of cellular respiration was investigated. The rate of cellular respiration should be optimal for room temperature and thus should occur best in germinating seeds at room temperature. Respirometers were set up with germinating peas, dry peas & beads, and beads alone, equal volume of each. The KOH absorbent cotton was added to consume any CO2 produced during cellular respiration. The beads served as control to account for atmospheric changes. After being equilibrated, the respirators were submerged in the water. As expected, the results of the data revealed the most oxygen consumption to have occurred in germinating seeds at room temperature (0.4293 mL O2 / min). This is because the rate of cellular respiration is highest under these conditions. At 10ºC the rate of respiration is significantly lower (0.1733 mL O2 / min) relative to room temperature. Germinating peas undergo cellular respiration, while in dry peas the cellular respiration is minimal. At room temperature the dry peas rate of oxygen consumption was (0.0253 mL O2 / min), as expected. At 10ºC the rate was even lower (0.0057 mL O2 / min), since almost no cellular respiration occurred at such low temperature in dry peas. The results revealed the relation between gas production and respiration rates as well as demonstrated the effect of temperature on the rate of cellular respiration. Sources of errors include the validity of the seals, since if there could have been a leak. Also, the absorbent cotton balls that were used for the KOH could have been too saturated. Another source of error could be at the temperature of the water baths. If a close eye wasn’t kept on the temperature, the ten degree Celsius would have fallen in degrees. Further research could be conducted using reptiles vs. mammals, and observing the rate of respiration in live animals.