Cellular Respiration

1. Cellular Respiration By: MaryKate, Jack, Emily, Reilly and JP

2. Background • Cellular Respiration Formula: C6H12O6+ 6O2 6CO2 + 6H2O + Heat Aerobic Respiration has 3 main steps: glycolysis, citric acid cycle and the electron transport chain Anaerobic Respiration is called fermentation. There are two types of fermentation: alcoholic and lactic acid.

3. Our lab • The cellular respiration experiment is testing to see how respiration rates change with different situations. By placing peas in a vial and changing the temperature one can examine the different rates of respiration. According to Avogadro’s Law at a constant temperature a mole of gas has the same volume as another mole of gas, therefore one must add potassium hydroxide, which creates a solid when reacted with carbon dioxide. The amount of water that enters the pipet determines how much gas has left the vial and the respiration rate.

4. Problem Statement • In this experiment we correlated the oxygen consumption of dried and germinated peas with their respective rate of cellular respiration.

5. Hypothesis • The germinating seeds will have a greater rate of cell respiration. The temperature of the seeds will not cause a major effect on the rate of respiration within the peas.

6. Materials • Room temperature water bath • Cold water bath • Container of ice • White paper • Water • Germinating peas • Non-germinating peas • Glass beads • Respirometers • Graduated tube • Absorbent cotton balls • Non-absorbent cotton • 15% potassium hydroxide solution (KOH) • Dropping pipets • Forceps • Thermometers • Clock with second hand • Calculator

7. Methods 1) Setup respirometers and water baths. · One bath should be room temperature while the other is 10oC. · Place a sheet of white paper on the bottom of each bath to assist in the reading of the respirometers. · Set up respirometers for each bath. (Place one absorbent cotton ball into bottom of respirometer and soak in KOH. Place a piece of non-absorbent cotton on top of the KOH) 2) Prepare peas and glass beads. · Put 25 mL of water in each respirometer. · Drop 25 germinating peas into a graduated tube and measure the volume. Place these seeds in a respirometer and seal. · Drop 25 non-germinating seeds into a graduated tube. Add enough glass beads to equal the volume of the first respirometer. Add these to the second respirometer. · Add enough glass beads into a graduated tube to equal the volume of the first respirometer. Place these beads in the third respirometer. · Repeat the last four steps to use for the second water bath. 3) Placement of respirometers: · Place one of each type of respirometer into one of each water bath. · Wait five minutes before proceeding. Check the volume of the pipet every five minutes.

8. How the apparatus works By placing potassium hydroxide (KOH) in the respirometer vial we were able to alter the equilibrium of the gas. The KOH reacts with the CO2 to form a solid enabling us to view the amount of oxygen consumption.

9. Results And observations

10. Results Continued…

11. Analysis

12. Discussion questions Q: State the controls used for each variable and any means used to correct for the influence of a variable: The variables that had to be controlled were temperature, amount of peas, and the size of the respirometer. The control for the temperature ice was added to make it colder, the control for the peas was the amount of peas placed in the respirometer, and there was no control for the size of the container itself. Another factor was the pressure within the container and the amount of carbon dioxide produced. Q: Which of the respirometers serves as a negative control? 2. Respirometer 2 served as a negative control. The corrected change in volume was the lowest of the three and was negative for the room temperature peas.

13. Discussion questions continued… Q: In reference to the general gas law, assuming your control measures worked, a change to which of the variables led to the observed change in volume? 3. The change in volume in the respirometer was caused by the change in pressure and carbon dioxide present in the respirometer. These factors caused the volume to decrease as space was filled with carbon dioxide gas and water was removed.

14. Discussion questions… Q:Using your graph and data tables, summarize your findings, comparing results from respirometers 1 and 2, and results obtained at room temperature vs. results at the colder temperature. Speculate as to cause of any differences between the treatments. 5. The differences in the treatments of cold and warm show the difficulties of respiration in the cold. The difference between the germinated and the dry peas has to do with the fact that the non-germinated are less active and consume less oxygen.

15. Discussion questions… Q: Calculate the rate of oxygen consumption for each treatment: 6. a) Germinating seeds at room temp = .34 mL/min b) Germinating seeds at colder temp = .26 mL/min c)Dry seeds at room temperature = .01 mL/min d) Dry seeds at a colder temperature= .015 mL/min

16. Conclusion • We proved our hypothesis to be correct because the germinating peas consumed more oxygen than the dry peas in both temperatures. We were wrong about the temperature because the peas at room temperature had a higher rate of oxygen consumption.