Cell Respiration Lab

Purpose

The purpose of this lab was to see how as cell respiration happens, CO2 levels rise and O2 levels drop. Also, the purpose was to see the rate that these levels change and if the environment changes, how would these rates change. We also used it to analyze the difference between cell respiration in a germinated plant and a dormant one.

Introduction

  Every seed grows into plants. Plants don’t grow overnight they need soil, temperature and water.   Plants spouting of a seeds into growth are called germination. The cell respiration formula for ATP is C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy.  There are three steps in the cell respiration that are Glycolysis, Krebs cycle and Electron Transport Chain. The glycolysis is when the breakdown of a glucose molecule into three- carbon molecule.  It happens in cytosol and oxide glucose into  pyruvate. The Krebs cycle doesn’t always have to need oxygen.  It happens in the mitochondria.  The Krebs cycle begins with acetyl. It is broken down into carbon dioxide. The first two cycles make ATP, but not that much. The electron transport chain needs oxygen and produces the most energy. It happens in the inner membrane of the mitochondrion.

Methods

The first step of our experiment
was to take the temperature of
the room. It read 20 degrees
Celsius.

Secondly, we received 25 glass balls,
put them into the bio chamber,
and measured their CO2 and O2
levels for a control group.  

Thirdly, we got 25 non germinated
bean seeds.

We measured the level of CO2
and O2 just as we did the glass balls.

Next,  we got 25 of the
germinated bean seeds.

We measured the CO2 and O2
levels for these as well.

After that, we took the 25 germinated
seeds and put them into ice water, and
let them soak for about 2 minutes.

We measured the temperature of the
ice water; it was measured at 4 degrees
celsius. 

 

Finally, we took the CO2 and O2
levels of the cold germinated seeds.

Table 1
Condition	Temperature (°C)
Room	20°C
Cold Water	4°C

Table 2
Peas	Rate of Respiration (ppm/s)
Germinated, room temperature	.009 ppm/s
Non-germinated, room temperature	.019 ppm/s
Germinated, cool temperature	.140 ppm/s

Discussion:
Cell respiration is the chemical process that makes most of the energy in the cell. Respiring cells take in oxygen and give off carbon dioxide. Specifically, O2 is an input of oxidative phosphorylation and CO2 is an output of the Kreb's Cycle. If you took a glance at our glass bead graph, you'd notice that the CO2 slope is barely a slope at all. It was a whopping .009. In a perfect world, the slope would be 0, because beads don't grow, give off carbon dioxide, and/or undergo cellular respiration. But hey, you can't win 'em all. At least the class average was .03.
Non germinating beans the slope came out to .0191, which is slightly larger than the glass bead slope of CO2. This happens because even though these beans aren't growing (AKA they're dormant), all cells need energy to survive. Meaning basically they need to take in carbon dioxide and release oxygen in order to not die.
On the other hand, germinating beans gave us a CO2 slope of .139 and an O2 slope of -2.348x10^-4. In other words, CO2 concentration is increasing while O2 concentration in the chamber is decreasing. When a bean is germinating, it means it's still growing; it requires energy for growth and development. Therefore the beans are increasing O2 consumption.
Lastly, we have our cold germinated beans. As temperature decreases, the rate of cellular respiration should decrease as well. Enzymes essential to cellular respiration are known to work fastest at certain optimal temperatures. So when the temp is too low, the enzymes can't function as effectively. The class averages give a good example at this; the cold germinating beans had a CO2 slope of .16 while the room temperature beans that had a slope of .22. Oddly enough, our CO2 slope was .14, about the same as our germinated beans. There's a possibility that we didn't leave the beans in the water for long enough, or we took too much time transferring them to the chamber, or the water wasn't quite cold enough. So many possibilities for error. Next time, if there's a freezer available, it might be beneficial to store some beans and peas in there, as the temperature will be held constant for a longer period of time.
With the exception of the cold germinated beans, our results do support our hypothesis. We thought that the slope would be almost nonexistent for glass beads, that non germinating beans would give off a very slight amount of carbon dioxide, and that for germinating beans the oxygen slope would be negative while the carbon dioxide slope would be positive.

Conclusion

In the cell respiration lab, we found out the germinating beans produced  more co2. The Co2 concentration was rising while the O2 in the chamber was deceasing.  The predicted outcome was correct.  We predicted that if the environment changes the rates would change. Through our graphs we were able to prove this. In our experiment we showed how CO2 and O2 must have changed environments for rate would change.