Cellular Respiration Lab

Purpose:

The purpose of this experiment was to see whether germination and temperature affect the amount of CO2 released. We were testing to see if germination on (barley) seeds would affect their cellular respiration process and eventually cause them to not produce CO2. The independent variable was whether or not the seeds were germinated and if the temperature changed. The dependent variable was how much CO2 was released. We wanted to see how much of a difference there would be between the four groups we tested out.

Introduction:

The lab we were about to conduct dealt with the process of cell respiration. Cell respiration is the series of metabolic processes by which living cells produce energy through the oxidation of organic substances. This conversion is done to benefit organisms because it converts chemical energy into a form that can be readily used. This is shown through the following equation:

C6H12O6  +  6O2 →  6CO2  +  6 H2O  +  Energy (ATP)

It is a fact that all animals and plants go through this process of oxidizing glucose for energy. Therefore, barley seeds with go through this process as well. We know that different variables may alter or affect carbon dioxide product during respiration (such as germination and temperature).

Methods:

For this lab, we would be performing the same practical procedure a multitude of four times, each with a different barley seed. We would begin with germinated barley seeds, twenty five of them that had been wrapped in moist paper towel for a period of time. Those seeds would then be blotted dry and the temperature of the room would be taken for comparison of a later trail that would compare the effect that temperature could have on the CO2 release of the seeds. With the room temperature recorded and the germinated seeds blotted dry, all twenty five would be placed into a carbon dioxide reading chamber which would then be connected with our LabQuest to graphically show the amount of CO2 being released from within the chamber. In order to get an accurate reading of the carbon dioxide being released from the germinated seeds, they would be left in the chamber to collect data for a minimum ten minutes. Once the time had passed and data for the graph on the LabQuest was present, the seeds were taken out and put into a beaker of cold water that had ice in it as well. Whilst the germinated seeds cooled in the cold beaker water, the CO2 probe that was taking carbon dioxide readings in the chamber was to be fanned with paper for a minute total and the chamber itself was washed out with water and then thoroughly dried with paper towels. Once the chamber was dried, we were ready to begin the alteration to our testing trials which would then provide us with data to see the effects that temperature has on the release of carbon dioxide from our seeds. The germinated seeds that we had put in the ice beaker would then be taken out and blotted dry with paper towel and then placed in the carbon chamber to begin collecting data on our LabQuest for ten minutes just as we had done before with the room temperature germinated seeds. The very same processes would be again repeated for our twenty five non germinated seeds as well as for our control group of glass beads, the only exception being that the glass beads would not be chilled in a beaker of cold water. The graph that we collected from all trials would be stored on our LabQuest and we would calculate the slope of the graph for each trial run for comparison. Once all the runs were completed we compiled the graphs together so that the differences between all of them would be visually easier to see.

Non-Germinated barley seeds

Germinated barley seeds

Testing for CO2 release

Checking temperature change

Data:

Graphs:

Discussion:

Our graphs show that for the non-germinated barley seeds, as time went on, the release of CO2  decreased. For the germinated seeds, as time went on, the release of CO2 increased. For the germinated seeds in cold water, as time went on, the release of CO2  decreased. The control group (glass beads) had no change in CO2 release, and it's slope was 0.

The data for germinated seeds in cold water was very similar to the non-germinated seeds and for both the release of CO2  decreased. However, the germinated seeds increased in the release of CO2  and the control group remained constant.

The amount of CO2 produced by the germinated seeds in cold water and the non-germinated seeds was about the same. This showed that both germination of the seeds and temperature change have an effect on the amount of  of CO2 released.

What we did well in this lab was that we had an accurate indication of both variables (germination and temperature change). However, what we did badly in this lab was that our control group data was not helpful. It was probably tampered with, so it's information is almost useless to compare to the other test groups.

The validity of our data is not very good. Our data was too low compared to other in the class who also did barley seeds. It was off by a good 0.12-0.24 ppm/s. It was double what we had. However, our data was at a reasonable range, so it wasn't completely off. Also, when compared to the average at room temperature Mr.Filipek gave us, our data wasn't too far off.

Going off what we talked in class, we thought that temperature and germination would affect the barley somehow. Obviously the groan shows that these variables do affect the amount of CO2 released, so we were able to support this hypothesis.

Conclusion:

The question we were trying to answer was does germination and temperature affect the amount of CO2 released?

Obviously they do affect the outcome, and our data supports it. For instance, the slopes between the germinated seeds in cold water and the non-germinated seeds were very similar. The amount of CO2 produced was also very similar between the two. Also, based on the control group (the glass beads) given to us, the germinated seeds at room temperature data was very close to that average.  

What we did wrong in the lab was that we messed up the outcome of the control group. We believe the glass beads test was tampered with, whether someone knocked it over or it was left out too long. If we were to do this experiment again, we would fix that part and do multiple trials to make sure the first trial was not faulty.