Surface area: Volume ratio importance Biozone p79 - 80

Lesson intention: 1) Investigate the relationship between surface area and volume of cells and organisms.

Terminology clarification: Surface area: Area of the outermost layer How big the exposed area of the object is. CUBE (typical model used for cells) surface of one side x how many sides there are surface of one side = l x b how many sides there are = 6 SO = 6 x (lxb)

Volume: amount of space occupied by an object … a. k. a Volume: amount of space occupied by an object … a.k.a. how much stuff can fit inside CUBE (typical model used for cells) length x breadth x height SO = l x b x h

In summary: Surface are: volume ratio 6 x (lxb): l x b x h But…. So what?

Larger cells would require more nutrients to keep them alive, just as a larger animal needs to eat more than a smaller animal.

The larger the cell, the longer it will take for nutrients to reach the organelles, which could lead to the death of the cell.

Small cell = large surface area: volume ratio 3:1 Large cell = small surface area : volume ratio 1:1

Surface area: volume ratio is a factor which limits cell size Surface area: volume ratio is a factor which limits cell size. Cells reach the perfect size, and will remain basically unchanged no matter which organism they are in, the only difference is the number of cells. The larger number of cells does still slow down metabolic processes, even if the cells are the same size. If a large surface area is required, cells can adapt with microvilli.