Square Supply, Cube Demand

You'll learnwhy surface area and volume grow at different rates, so bigger cells run short of surface.

A cell feeds itself through its surface and spends everything through its volume, and the two do not grow at the same rate. Double a cell and its membrane goes up fourfold while its interior goes up eightfold — which is why cells stay small, divide, or grow a fringe. Twelve short steps; press Next for each one.

12 STEPS · 6 QUICK CHECKS · CUBE CELL · SA = 6s² · V = s³ · SA:V = 6/s · RATIO, NOT TOTAL · v5

cube cell · SA:V = 6/s · the ratio only falls

Before you start

What you're looking at

One model cell drawn as a cube of side s, with supply crossing its surface and demand inside its volume.

The question

As a cell grows, why does its surface fall behind the volume it feeds?

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