Sunday, November 17, 2013

Cellular Respiration Lab

Purpose: The purpose of this lab was to observe the effects of cellular respiration on different carbon dioxide concentrations, study the effects of temperature on cellular respiration, determine whether germinating or non-germinating corn respire, and compare the rates of cellular respiration between germinating and non-germinating seeds.

Introduction:  Celllular respiration is converting the chemical energy of molecules that can be used by organisms. Both plants and animals break down glucose for energy and there is a three step process cellular respiration.the first step is glycolysis which creates two pyruvates for the next step along with a net of two ATP. The pyruvates oxidation is not a huge step but creates acetyl CoA from the pyruvates. This will be fed into the citric acid cycle and generate more ATP as well as Electrons carried to the last step which is oxidative phosphorylation and chemiosmosis by NADH AND FADH2. The final step creates the most ATP in the whole process.

Methods: In the experiment, we measured how different levels of carbon dioxide affected the rate cellular respiration, for ten minutes and in a closed system, on 25 room temperature and 25 chilled germinating corn seeds, 25 non-germinating corn seeds, and 25 glass beads. We began with the germinating corn seeds. We then soaked the same 25 germinating seeds in 4°C water for about 10 minutes.  We then tested non-germinating seeds. Finally, we tested glass beads. Glass can’t perform cellular respiration, as it is non-organic. The fact that glass beads were so similar in size to the corn seeds made it the perfect control group. 

The setup.

Getting a reading from germinated seeds.

Germinated seeds getting cold.


Graphs and Charts:
y= CO2 concentration    x= time (in seconds)
(The blue line is the normal germinating seeds, and the green line is the chilled germinating seeds. The red line is the non-germinating seeds, and the purple line is the glass beads.)

Discussion: The result for the germinating seeds was a positive slope for the whole ten minutes of recording, with a final reading that was roughly 1½ times the starting concentration. This should be expected from seeds that are actively using oxygen to grow and release CO2 as a product. Since non-germinated seeds are dormant seeds, which means that they can’t perform cellular respiration, the result was a slope of nearly zero because they simply weren’t actively trying to grow, which would produce CO2. The result was similar for the cold germinating seeds: a slope of zero for the first 1½ minutes of recording, and then a positive slope for the remaining amount of time. That most likely occurred because the seeds were cooled so far below the optimal temperature that they require to perform cellular respiration, they had to warm back up to room temperature before they could begin cellular respiration. As a result, the CO2 concentration in the chamber filled with cold seeds was very similar to that of the ungerminated seeds.

Conclusion:  temperature did play a large role in the rate of respiration as all the test subjects showed the same correlation. With germinated being the fastest, germinated cold getting slower and non germinated being the slowest. We conclude that lower the temperature had a negative impact on the seeds.

References: N/A


1 comment:

  1. Nice Job! In your discussion, try to reference actual data from your experiment to support your ideas.