Science Starter #9 – 10/21/16
Sketch one animal cell and one plant
cell. Describe how you know which one
is which.
Notes 3.6
CELL SIZE AND SHAPE
PP. 72-73
Cell shape
•Cell
shape reflects function of cell
•Ex: long extensions of nerve cell send and
receive messages
•Skin cell-flat, plate-like to cover and protect
Surface Area and Volume
•Surface Area: a measure of the total area
that the surface of an object occupies;
area exposed to the environment
•Volume: amount of 3-dimensional space
an object occupies
Cell size
Cell size is limited by its surface area-to-volume ratio
Larger the cell, the volume increases faster than its
surface area.
•
•
•
Surface area to volume ratio decreases with increasing
cell size (EX. 6:1 vs 3:1)
Why is a cell small?

Difficulty exchanging materials
(such as nutrients, oxygen, and
waste products) across the cell
•Why
is this important to the cell?
Substances cannot get to the center, or
out of the center of the cell fast enough
if it’s too big