First difference we noticed that there were bubbles at the top of the solutions in each flask and that the solution itself was cloudier than when we first prepared it.
The results are as follows:
Averages for above results:
These tables show the general increase of yeast cells per B-square. The averages are taken from the two trial from each test and then a general average is made from that. This is to provide a clearer view, but still not as clear as a graph. These averages are then used to make the graph. The most important part of data processing for this lab is the percentage increase, which begins on page 6.
Graphic representation:
Series 1: The first set of results.
Series 2: The second set of results, two days later.
The graph shows that the 100ml flask has a higher cell count than the 250ml, but the 500ml flask obviously has the highest count.
Concentration of yeast cells in each flask pr. ml:
The next set of tables shows the concentration of yeast cells in each flask per ml. This is the most important of the results as this shows the actual increase of cells
Day 1:
Day 3:
These results were found by taking the average amount of cells and multiplying it by 0.000004. You divide by 0.000004 because since all the blocks we used to count the yeast cells are in the B-square (part of the grid on the special haemocytometer) and each B-square is 0.04mm³. You can also choose to multiply by 250000. You get the same results.
Flasks
Another example is the flasks circumference. The flask circumference (110ml of H20) is as follows:
100ml = 15.0 cm
250ml = 25.0 cm
500ml = 32.8 cm
This shows the general increase in the flasks surface area and puts into a brighter light of how big the differences between the different ratios actually are. The way you do this is by using the formula: C= 2piR. So to get the area you just use the formula: pi * R².
The Surface area is going to be
100ml = 17.9
250ml = 49.74
500ml = 85.61
So the surface area to volume ration is going to be
1:0.16, 1:0.45, 1:0.78.. switch the one and the decimal around
Percentage Increase:
This shows that the larger the surface area of the flask, the more oxygen and therefore a faster and more efficient aerobic cell respiration. The way I found the averages was by taking the second sets of results (the ones taken 2 days after the experiment begun) and then divided it with the original results and multiplied by 100.
For example, say the original result was 50 and the result taken two days later was 100. The formula would look like this: 100 : 50 * 100 = 200%. This is the percentage increase.
This data is the most important as it shows in a much clearer way how much cell division actually took place.
Conclusion: Theoretically the hypothesis, that states aerobic respiration produces more energy than anaerobic respiration, is correct. The larger flasks contained a larger percent increase due to there being more oxygen in the larger ones. More oxygen means aerobic respiration is much more rapid and therefore a more rapid cell division. The results prove that more energy is produced from aerobic respiration than anaerobic respiration: the smaller flasks contained less oxygen and therefore aerobic respiration was lower. This shows the relationship between the surface area of the flasks to the cell counts: Larger surface area = more Oxygen (O), which in turn means a faster and more efficient aerobic cell respiration. If anaerobic respiration produced more energy then it wouldn’t have mattered how much oxygen was in the flasks, as the anaerobic respiration would’ve produced enough energy to allow a fast cell division. According to the percentage increases, this hypothesis was proved correct. Also by seeing the large increase of the concentration of yeast cells in each flask per ml. What these results tell us is that even though in practice, the 100ml flask had more yeast cells than the 250ml; the 250ml had a larger percentage increase. This proves that since there was more oxygen in the 250ml then aerobic respiration does produce more energy.
However, due to misunderstandings, our results are possibly corrupt. On the first day of the cell respiration experiment we misunderstood the way to prepare the specimen for examination. Instead of using the pipette to place the sample of the yeast-apple solution in the ridge of the slide and placing the cover slip over it, we dropped a sample of the solution onto a cover slip, put another cover slip on top of it and placed the sample in between the two cover slips onto the slide.
Ridges
(Slide)
You can see here that the ridges are there for a purpose and if we had read the apparatus sheet included with the experiment that explained how exactly we were to set the sample up, we would have been able to produce much clearer results and been able to write a better and more beneficial lab report proving or disproving the hypothesis.
Here you can see how we used two cover slips with the sample in between (sample shown by the yellow line)
Luckily the second part of the test we made the specimens correctly so not all the data is completely corrupt, only the first part. Perhaps we didn’t shake the flasks well enough as we should have. We noticed that the yeast cells had a tendency of ‘clumping’ together instead of being spread out evenly. This could be due to one of the two microscopes we used was faulty. Because of the time limit, we were forced to keep the results we had which probably also contribute to why the 3rd day results of the 250ml flask are a bit odd as those were the results we got with the faulty microscope.
The second part of our experiment we were running short of time and decided to use two light microscopes, as I mentioned before. We discovered that this saved a lot of time and afterwards we concluded that we should’ve used at least two light microscopes to begin with. This way we would’ve been able to have enough time to redo the specimens and repeat the experiment. This was not the case for the second part of our experiment, as noted in the previous paragraph.
Another explanation could be that we rushed the counting and counted either too many cells or too few.
If we had the chance to redo this lab, there are a lot of things I would do properly the second time. First, most obviously being, making proper samples, as well as incorporate all the other ideas that I mentioned above.
