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At what scale

LuisanaT's picture
Life, as we have been studying it, starts off with small single celled organisms and gradually includes more and more multicellular ones. The introduction of these larger organisms has not by any means replaced the single celled one on this planet. This impels one to consider whether there is any difference in the actual cells found in either group that could account for this. If all things are made up of the same building blocks, and we are all composed of cells, does that mean that they are all the same cells?

But comparing organisms at this scale is not small enough to make that assumption credible. This is because the progression towards complexity translates to organisms having more intricacies and the need for more space to encompass it all. Aside from being multicellular, eukaryotes have more organelles than most prokaryotic unicellular organisms. This allows the cell to perform tasks for complex organisms to survive that are not needed for simpler organisms, showing how not all cells are necessarily the same at a microscopic level of examination. With this in mind, the differences in cell function should render a difference in cell structure and ultimately in cell size. Using this idea, my group came up with the hypothesis of there being a direct correlation between the cells size to the size of the organism.

In order to question this notion, we decided to utilize the sample of cells from a variety of sized organisms. Using a microscope, not only were we able to measure the diameters of the different cells but we were also able to make clear distinctions amongst the cells. We discovered that the human cheek cells were entirely of a light blue color. The buttercup cells we looked at were a light shade of green. The coleus stem tip cells, under the microscope, were purple and also had blue lining its membrane. And the last species we examined, the pine tree stem cells, had an assortment of colors, for it was purple, dark brown, light blue, and burgundy. Acknowledging the fact that these different cells can differ in color, we were better able to imagine that they could also differ in relative size.

Our observation of the actual size is as follows:


Average Diameter (microns)





Coleus stem tip


Human cheek


Pine stem


Based on our information, there isn’t a positive correlation between the size of a cell and the size of the entire organism, refuting our original implications. The paramecium, the smallest of the organisms we examined, had the largest average diameter of 186 microns. While the smallest average diameter of 13.0 microns came from the pine tree, the tallest organism amongst the specimens. Does all of this mean then that it is impossible to look at and make valid conclusions about life in contrasting scales?

Maybe the problem is that one is not looking at life in the right scale to get the answer that is right for their question. Because what this information does affirm, a question these observation could have answer is that there is an inverse relationship between the two. One story that could account for this is that all multicellular organisms are created from one equally sized cell. When undergoing the multiplication process, the original cell amount is split and therefore minimizing the size of the individual cells. This would explain why larger organisms have small cells because it works to compensate for the elongation.