Cellular Respiration

Kera Pezzuti The purpose of this investigation was to examine the effect of temperature on the rate of cellular respiration using peas. The rate of cellular respiration was compared in germinating and nongerminating peas and the peas were placed in water of either 25o C or 10o C. Data was determined by the amount of O2 consumed. Each group was supposed to set up six respirometers with three placed in water that was either 25o C or 10o C. However, due to time restraints, each group only set up three respirometers and placed those three into either 25o C or 10o C. A 100 ml graduated cylinder was filled with 50 ml of H2O. 25 germinating peas were dropped into the gradulated cylinder and the amount of water that was displaced was determined. This volume was then recorded and the peas were removed. The graduated cylinder was then refilled with 50 ml of H2O and this time 25 dried peas or nongerminating peas were dropped into the graduated cylinder. Then glass beads were added in to attain a volume that was equivalent to that of the germinating peas. These peas and beads were then removed and placed on a paper towel. The graduated cylinder is then refilled for a third time with 50 ml of H2O. Glass beads were dropped into the graduated cylinder until the required volume or the volume equivalent to that of the germinating peas was reached. These beads were then removed. Then the respirometers had to be assembled. A small piece of cotton was placed on the bottom of each vial and the cotton was moistened with 15% KOH. Then a small wad of nonabsorbent cotton was placed on top of the KOH-soaked absorbent cotton. Then the sets of germinating peas, dry peas plus beads, and bead were placed in separate vials. The stopper fitted with the calibrated pipette was inserted. A sling of masking tape was made and attached to each side of the water baths to hold the pipettes out of the water during the equilibration period of seven minutes. Following that the three respirometers were submerged under 25o C or 10o C water depending on which was assigned. After the three respirometers are submerged the respirometers equilibrated for three more minutes and then the initial position of the water of each pipette was record to the nearest .01 ml. Every 5 minutes for the next 20 minutes reading of the water’s position in each pipette were recorded. In the end, the results were that the germinating peas were the only peas performing cellular respiration and that as time passed, the oxygen levels were decreasing due to the fact that cellular respiration was occurring. Nothing occurred in the nongerminating peas because they were still dormant, and therefore were not active and of course the bead could not perform cellular respiration because beads are nonliving things. Also, the respirometers that were submerged in 25o C water performed more cellular respiration, showing that the warmer the temperature is, the more cellular respiration can occur. For our 25o C water, the reading in our bead respirometers changed very little. Initially it was 2, then 1.88 at 5 minutes, then 1.87 at 10 minutes. There was no change for 15 or 20 minutes. Our readings for our dry peas and beads combined was initially above 2, then dropped to 1.95 after 5 minutes, and was at 1.875 at 10 minutes. At 15 minutes, the reading was of 1.84, and at 20 minutes it was 1.81. There was great difference in the readings for the germinating peas. Our initial value was 1.78 which was followed by 1.56 at 5 minutes and 1.33 at 10 minutes. At 15 minutes it dropped to 1.08, and was at 0.82 at 20 minutes. This investigation can be used in life in numerous ways. By determining the effect that temperature has on cellular respiration a person can determine under what temperature a plant will grow best or perform the most cellular respiration. In addition, a person can also determine whether their plant has germinated or not based on whether or not the plant is performing cellular respiration.