BIOLOGY FORM 5 CHAPTER 1: 1.1 IMPORTANCE OF A CIRCULATORY SYSTEM
BIOLOGY FORM 5
chapter 1 - Transport
1.1 : Importance of a
1.1 Understanding the importance of having
a transport system in some multicellular
Dimension of cube (cm) 1 x 1 x 1 2 x 2 x 2 4 x 4 x 4
Total surface area of cube (cm2)
Volume of cube (cm3)
Calculate the TSA/V ratio.
• Three cubes of agar are prepared which
contain the indicator phenolphthalein.
• These are placed in hydrochloric acid which
will diffuse into the cubes.
• As it diffuses in it will turn the indicator
• As the size of the cube increases the surface
area to volume ratio decreases.
Width of cube
Surface area: volume
1 6 1 6
2 24 8 3
3 54 27 2
• The cubes look like this after a few minutes.
• If these were real cells then the bigger cell
would not have received what it needs to all
parts of the cell.
• Therefore it would need a bigger surface area
in order to rely on diffusion.
• Watch this video to see the experiment in
How to circulate substances?
No Specialized Circulatory System