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Cellular Respiration Lab

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Susan Lee

on 16 November 2013

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Transcript of Cellular Respiration Lab

Part One: Measuring O2 consumption of germinating versus non-germinating peas in room temperature and 10°C water baths using microrespirometer
Purpose/Summary:

The purpose of part one of the lab is to study cellular respiration in germinating versus non-germinating peas by measuring and comparing their consumption of O2 in milliliters using microrespirometers submerged in water baths.
In part one, students compared the cellular respiration rate of germinating and non-germinating peas for the two experimental groups as well as glass beads for the control group. Additionally, students compared how temperature affects cellular respiration by manipulating the temperatures of some water baths to 10°C while leaving some water baths at room temperature. In order to properly use the respirometers, students also needed to know the ideal gas law (PV=nRT) in order to quantify O2 consumption rates.
Cellular Respiration Lab
by Dhakshi Balakumar, Susan Lee, Josh Saha, Jenae Wilson, and Derek Wu

5th period
Independent Variables:
Type of pea seed (germinated/non-germinated)
Temperature of water bath (°C)

Dependent Variables:
Consumption of O2 (mL)
Part One Procedure Summary:
Methods
Purpose of KOH: Because CO2 is produced during cellular respiration, it will be removed by the KOH, which will absorb the CO2 so it won’t interfere with the experiment and instead form the solid K2CO3. Therefore, this experiment can eliminate additional factors affecting the results, so the respirometer will only measure the one variable, the consumption of oxygen gas.

Purpose of glass beads: The glass bead respiration chamber serves as the control for a unit of comparison to the two experimental groups.

Purpose of Equilibration in water baths: Equilibration must take place prior to officially beginning count because the respirometers need time to adjust to the temperature to become a constant and eliminate additional variables that could affect the results.
Background
Balanced chemical formula:
C6H12O6 + 6O2 → 6CO2 + 6H2O + energy

So, in other words, glucose reacts with oxygen in order to form carbon dioxide gas, water, and energy. The energy leaves in the forms of ATP, NADP+, and NADPH. The key products in cellular respiration are ATP, NADP+, and NADPH (In alcohol fermentation the products are ethanol, carbon dioxide, and ATP and in Lactic Acid fermentation the products are lactic acid and ATP.)

The ATP is later used by the cell in order to perform all of its vital chemical processes such as; shipping, transporting in and out of the cell, and performing various other functions.
The CO2 and H2O gas are exhaled through respiration and released into the environment, where they will be used along with sunlight to power photosynthesis, which provides the molecules needed to power cellular respiration, thus creating a cycle.
Part One: Data
group data slopes:
0.02 mL/min=germinating
0.0023 mL/min=non-germinating
0.001 mL/min=beads
Part Two (Student-designed): Measuring O2 consumption of mealworms in room temperature and 10°C water baths using microrespirometers

Purpose/Summary:

The purpose of part two of the lab is to observe cellular respiration in animals, and in this case, mealworms.
In part two, students measured the cellular respiration rate of mealworms by measuring their consumption of O2 in milligrams using the microrespirometers in water baths. Additionally, students compared how temperature affects cellular respiration by manipulating the temperatures of some water baths to 10°C while leaving some water baths at room temperature.

Independent variables:
temperature of water bath (Room or 10° C)

Dependent variables:
O2 consumption (g) over time

Part Two Procedure:
Part Two: Data
Conclusions:
Part One & Two
Corrected difference was calculated by subtracting the given recording at a certain time from the original recording. The purpose for this was to see the change in the amount of oxygen, which shows the amount of oxygen consumed.

The slope of the graphs are the average rate of consumption of oxygen in milliliters over a time period of twelve minutes. Therefore, this slope represent the average respiration rate.
class average slopes (room temp.):
0.0203 mL/min=germinating
0.0028 mL/min=non-germinating
class average slopes (10 C):
0.0117 mL/min=germinating
0.0403 mL/min=non-germinating

Background
The ideal gas law is an approximation of different
behaviors gases will undergo in numerous conditions.
PV=nRT
P= pressure of gas
V= volume of gas
n= amount of molecules in gas
R= specific gas constant
T= temperature of gas

Respirometers are used to measure the change in gas volume. This instrument can show the overall rate of cellular respiration in the germinated and dormant peas.The oxygen gas is being consumed by the cells while carbon dioxide is diffusing out of the cells.

Two variables that can affect the respirometer measurements are temperature and pressure. Volume and pressure have an indirect relationship. As volume increases, the pressure of the substance will decrease proportionally. Temperature and volume are directly proportional. As temperature increases, the volume will also
increase and vice versa.

Background
Germination in plants is the process when a dormant seed sprouts and grows into a seedling during ideal conditions. Germinated seeds require a lot of energy in order to break their seed coat. Therefore, respiration is required in order to get this energy and therefore, they have a relatively high metabolism rate. On the other hand, dormant seeds require very little respiration and therefore, they have a relatively small metabolism rate. So, overall, germinated seeds have a higher metabolism rate than dormant seeds because of the amount of energy they require for their respective processes.

Adaptive value of dormancy in seeds: Seeds can remain dormant during unfavorable conditions so the embryo will only grow at suitable times. Dormant seeds are able to survive without water; therefore, if there is a drought, the plants can survive. Additionally, these seeds are easily transported by animals and wind, so the plants can easily colonize vast areas. The seed coat protects the embryo and provides food for it until it can grow on its own.
The rate of respiration is greater in germinating peas than in non-germinating peas. Additionally, temperature and respiration rates are directly proportional to one another. The peas contained in the respirometers placed in the water at 10 degrees Celcius carried on cellular respiration at a lower rate than the peas in respirometers placed in the room temperature water. The non-germinating peas consumed far less oxygen than the germinating peas. Although germinating and non-germinating peas are both alive, germinating peas require a larger amount of oxygen to be consumed so that the seed will continue to grow and survive.
The results of the student-designed lab is consistent with the relationship between temperature and enzyme activity. At higher temperatures, enzyme activity increases, and conversely decreases at lower temperatures. This is because the heat causes the molecules (substrate) to move at a more rapid speed and collide more with the active site of enzymes, thus increasing the reaction rate of the enzyme. In the student-designed lab with mealworms, the data indicates that the mealworms that were submerged in the room temperature bath had a higher respiration rate then the mealworms in the 10°C water bath.
Hypothesis: Germinated peas will respire at a faster rate than glass beads.
Null Hypothesis: Germinated peas have the same respiration rate as glass beads.

T test value: 2.942

This T test value gives us a p-value between .02 and .01 (exactly .0187,) which is low enough to disprove the null hypothesis, and therefore prove the hypothesis.
Numerous errors could have occurred during the experiment. The cotton placed in the vials could have been at different lengths. To avoid this mistake, the cotton is supposed to take up 1.5 centimeters of the vial. The potassium hydroxide was placed on the cotton balls to react with the carbon dioxide. Thirty drops were placed inside the respirometer. If the pipette was not used correctly, each drop of KOH could have come out a different size, so each vial would have a different amount of the solution. After everything was placed into the respirometers, they needed to be sealed tightly so air and water could not make it inside. To avoid leaky respirometers, each individual in the group could take turns securing the respirometer together. One set of the experiment was done in water at 10˚C. Ice needed to be constantly added to keep the water at the same temperature. If the temperature increased, that could affect the respiration rate and speed it up. Movement during this experiment could have also affected the respiration rates. When a person bumps or shakes the table and vials the pressure could fluctuate. When the pressure changes the volume changes. It is easier to stand away from the tables and walk carefully, so the data does not change drastically.
SLOPES
Mealworms at Room temperature= 0.0067 g/min
Mealworms at 10 C=-0.001 g/min
5. Set up a sling by placing a long strip of masking tape over the water bath; then, put the chambers in the water and lay the pipette portion onto the sling in such a way so the numbers are readable. Leave them like this for 7 minutes, so they can adapt to the new temperature.

6. After, put just a drop of food coloring to the pipette tip and then gently place the pipettes into the water until they are completely submerged. The food coloring will help identify the exact O2 level.

7. Wait for 3 minutes, and then take the first recording; this will be the initial value. Every 3 minutes until the 12 minutes are up, measure and record the O2 level.

8. Clean up using proper safety protocols.
Glass beads at 10C= 0.0027 g/min
Glass beads at room temperature= 0 g/min
Part One Procedure Summary:
Methods
1. Set up the water bath in the black tub that is deep enough to submerge the chambers. Room temperature water should be at 22 degrees Celcius.

2. Prepare 3 respirometer vials by filling it up with 1.5 cm of cotton. Then, soak the cotton with KOH by adding 30 drops of KOH using a pipette. After, layer it off with nonabsorbent cotton (fiber.)

3. Using a 100 mL graduated cylinder, measure the volume of solids by filling it with 50 mL of water and 25 germinating peas. Determine the water displacement and repeat for the other two.

4. Finish setting up the chamber by adding the solids into the respirometer, sealing it with a rubber stopper/pipette, and placing the metal washer around the pipette to weigh it down in the water.
1. Set up the water bath in the black tub that is deep enough to submerge the chambers. Room temperature water should be at 22 degrees Celcius and cold temperature water should be at 10 degrees Celcius.
2. Prepare 4 respirometer vials by filling it up with 1.5 cm of cotton. Then, soak the cotton with KOH by adding 30 drops of KOH using a pipette. After, layer it off with nonabsorbent cotton (fiber.)
3. Gently get 10 mealworms and measure their mass in a weighing boat; make sure to zero the weighing scale. Repeat this once again for the second experimental group in cold temperature water. Then, using an electronic scale, measure the mass (g) of the glass beads to equal the mass of the mealworms.
4. Finish setting up the chamber by adding the solids into the respirometer, sealing it with a rubber stopper/pipette, and placing the metal washer around the pipette to weigh it down in the water.
5. Set up a sling by placing a long strip of masking tape over the water bath; then, put the chambers in the water and lay the pipette portion onto the sling in such a way so the numbers are readable. Leave them like this for 7 minutes, so they can adapt to the new temperature.
6. After, put just a drop of food coloring to the pipette tip and then gently place the pipettes into the water until they are completely submerged. The food coloring will help identify the exact O2 level.
7. Wait for 3 minutes, and then take the first recording; this will be the initial value. Every 3 minutes until the 12 minutes are up, measure and record the O2 level.
8. Clean up using proper safety protocols.
Non-germinated seeds had a much slower rate of respiration than germinated seeds because they are dormant, and therefore require much less energy; additionally, they do not do as much respiration, which doesn’t consume as much oxygen. Germinated seeds had a much higher rate of respiration because they’re actively growing, requiring much more energy, and going through respiration faster, so consequently, consuming more oxygen. Germination causes the seed to go out of dormancy and into growth; importantly, growth requires energy, while dormancy does not require as much.
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