Cellular Respiration Lab

Purpose: 

The main objective of this lab was to find out the rate of respiration in dormant seeds, seeds which were germinated, and seeds which were germinated and added to cold water. The temperature was the dependent variable as it was changed from room temperature to ice cold water. The environment, sensor and type of seed used remained the same, making it the independent variable. The main focus was to see the difference temperature makes in the respiration of germinated and non-germinated seeds.

Introduction:

Cellular respiration is a form of aerobic respiration in which glucose is broken down in in order to produce ATP. The general formula for cellular respiration is C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy. This process takes place in the mitochondria. Cellular respiration has 3 stages: glycolysis, citric acid cycle, and oxidative phosphorylation. At each of these stages, ATP is produced. During glycolysis, glucose is broken down into 2 pyruvate molecules. 2 ATP is required to phosphorylase glucose but 4 ATP are produced and 2 NADH. The pyruvate is then oxidized to acetly CoA and then goes on to the citric acid cycle. The citric acid cycle then produces 4 CO2  , 6NADH, 2FADH2 ,and 2 ATP. Finally, in oxidative phosphorylation, the electron transport chain and chemiosmosis are combined together. The total yield for a single molecule of glucose is 30-32 ATP.  Temperature affects the rate of respiration.

Methods:

25 similar pea seeds which were germinated had been counted and picked out along with 25 dormant seeds and 25 glass beads. The glass beads were used as a control group. We first tested the germinated seeds by simply putting them in a container covered with the respiration sensor. Then we had the germinated seeds sit in ice cold water and once again put them in the container covered with the sensor. The same thing was done with the dormant seeds to use as comparison. The glass beads were a control group to act against the dormant and germinated seeds. 

We used the Lab Quest to take all the CO2 measurements

The germinated seeds at room temperature

The cup of cold water that the seeds were to be put into

The seeds soaking in the Ice Water

Data:

The rate of respiration for all seeds

Graphs:

The CO2 Graph of the germinated seeds at room temperature

The CO2 Graph of the non-germinated seeds at room temperature

The CO2 Graph of the Germinated seeds after submerged in Ice water

 Combonation of all graphs 

Blue= Germinated at room temp

Purple= Germinated after submerged in ice-water

Green= non-germinated seeds

Red= Glass beads that served as constant

Discussion:

The rate of respiration for the peas at room temperature was .32 ppm/s. The rate of respiration for the peas at the cold temperature was .97 ppm/s. The rate of respiration for the non germinating peas was .05 ppm/s. The average rate of respiration for the peas was .446 ppm/s. The average rate of respiration for the glass beads was .015 ppm/s. The respiration rate was higher for the germinating peas when compared to the respiration rate for the non germinating peas. The temperature of the water also had an effect on the respiration rate of the peas. The peas that were in then cold water had a higher rate of respiration than the peas that were in the water at room temperature

Conclusion:

As shown in the graphs above it is obvious that the germinated seeds produce the most co2, but their co2 production rate decreases after they have been submerged in water. Also it should be noted that the non-germinated seeds barely produced more co2 than the glass beads. So it can be determined that the non-germinated seeds produce little or if not any co2.

 Reasources:

Campbell Biology Ninth Edition