Question:
Why are cells so small?
Claim:
Cells that have a larger surface area to volume ratio are more efficient at diffusing essential nutrients
Evidence:
Efficiency of Cell Diffusion in 16 minutes and 25 seconds
Cell size
|
2 x 2 x 2
|
1.5 x 1.5 x 1.5
|
1 x 1 x 1
|
Surface area to volume ratio
|
3:1
|
4:1
|
6:1
|
% cell receiving nutrients
|
87.5%
|
96.3%
|
100%
|
Rate of diffusion
|
.024 cm/min
|
.028 cm/min
|
0.3 cm/min
|
The smallest cube had the largest surface area to volume ratio and was also the most efficient at diffusing.
Reasoning/Justification:
Based on our evidence it was clear that our claim was correct because the cells that had the largest surface area to volume ratios were also the most efficient at diffusing nutrients. The 1 x 1 x 1 cube had the largest surface area to volume ratio and also diffused 100% of the nutrients in the time the other cells diffused only 96.3 and 87.5 percent. This means that the 1 x 1 x 1 cube was the most efficient at diffusing the nutrient, and this can be accounted for by the large surface area to volume ratio.
Alternative Claim:
The ratio of diffusion is related to cell size. Nutrients diffuse at a faster rate through small cells than they do in larger cells.
Challenge Against the Alternative Claim:
The data that was collected did not support the alternative claim. All of the rates were fairly close to each other. The cells were all timed for the same amount of time (16 minutes and 25 seconds) and we were able to see that the diffusion into each cube were only millimeters away from each other. If it the rate of diffusion was related to cell size, a significant difference in the diffusion rate of all three cells would have been observed.
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