Wednesday 8:00 A.M. Lab
March 2nd, 2005
In this lab we are measuring the amount of oxygen used in both germinating and non germinating peas. We are measuring the oxygen consumption by taking a reading of a respirometer submerged in two water baths. The first bath will be cold water and the second warm to determine the effect of temperatures on oxygen consumption. Our negative control will be glass beads to measure to increase or decrease in atmospheric pressure or temperature changes. There is a direct relationship between oxygen consumption and Carbon Dioxide produced, therefore the more O2 consumed the more CO2 produced. To keep the amount of CO2 produced from canceling out any pressure gained or lost from the consumption of CO2 we are adding KOH(Potassium Hydroxide) to the respirometers. Since the CO2 will be selectively removed the change in the volume of gas in the respirometer should be directly related to the oxygen consumed. In this experiment the germinating peas, in both water baths, should consume much more oxygen than the non-germinating peas or the glass beads, because germination has began thus accelerating cellular reactions and the rate of respiration. The cold water bath should slow the respiration down in all three respirometers. II. Materials and Procedures.
For this experiment we have prepared to water baths. One bath is ice water, around 10 degrees Celsius, the other warm, around 25 degrees Celsius. Both water baths will contain three respirometers. One with 25 germinated peas the volume measured in ml., one with the same number of peas with glass beads added to attain the same volume, and one with only glass beads to the volume of the other two. Added to the respirometers will be KOH(potassium hydroxide) to selectively remove any carbon dioxide produced with the consumption of oxygen. The three respirometers will be submerged in each bath and allowed to equilibrate. After the equilibration period the respirometers are submerged in the baths taking reading at 5 minute intervals, recording the amount of oxygen consumed in ml on the pipette attached to each respirometer.
III. Results/Presentation of Data
Our data recorded shows that the germinating peas did consume more oxygen than the non-germinating or the glass beads alone and that the cooler temperature did slow down the consumption of oxygen in the germinating peas. In both water baths the atmospheric pressure seemed to increase causing our reading to raise in our glass beads and non-germinating peas. This direct relationship in reading leads us to believe that the oxygen consumption in the non-germinating peas was minimal if any at all.
Ice Water Approx 10 Degrees Celcius Warm Water Approx 25 Degrees Celcius
Time (min) Glass Beads Germinating Peas Non-Germinating Peas Glass Beads Germinating Peas Non-Germinating Peas
0 0.74 0.61 0.75 0.9 0.91 0.9
5 0.75 0.52 0.8 0.9 0.63 0.9
10 0.8 0.47 0.85 0.9 0.375 0.91
15 0.85 0.43 0.89 0.92 0.195 0.92
20 0.87 0.37 0.91 0.94 Bubble Gone 0.94
25 0.9 0.33 0.93 0.96 Bubble Gone 0.96
Given the results we fail to reject our hypothesis. The temperature adversely affected the oxygen consumption of the germinated peas and the germinated peas consumed more oxygen than the non-germinating peas. With the warm observations the germinating peas respirometer ran out of room to measure oxygen consumption after 20 minutes of reading.