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AP Bio



Unit 2

2.3 Cell Size

1 min readjune 8, 2020



🦠 Cells, as you all know, are incredibly tiny. The cell needs to maintain a small size in order to have the maximum amount of space for the transfer of nutrients and waste (surface area) with the smallest volume of cell. The reason for this is as the volume increases, the cell will need more and more nutrients to enter, and the higher the surface area, the more nutrients can enter. 

Image courtesy of Wikimedia Commons

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The greater the surface area to volume (SA/V) ratio is, the more efficient the cell becomes. When the cell reaches a point where the surface area doesn’t allow enough nutrients to pass that the cell needs it divides. Tissues and membranes that have folds have them to increase the surface area.
The equation for this ratio is very straight-forward and can be found on your Equation Sheet for the AP Exam.


Image courtesy of CollegeBoard

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Unit 1: Chemistry of Life
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