AP Biology / Unit 2: Cell Structure and Function
2.2 Cell Size
Notes
Cells stay small because the surface-area-to-volume ratio falls as size increases. Exchange with the environment happens across the surface.
- Folding (microvilli, root hairs) increases surface area.
Practice
A cube with side 1 has SA:V of:
SA 6, volume 1.
As a cell grows, SA:V:
Volume grows faster than area.
Intestinal microvilli help by:
More surface for exchange.
Ready for more? Take the Unit 2 test.