1. The aim of the lesson today is to: 1.

2. Surface Area to Volume Ratio

3. Length of edge of cube / cm Surface area of whole cube / cm 2 Volume of cube / cm 3 Ratio of surface area to volume (χ:1) 1 2 3 4 5 6

4. Length of edge of cube / cm Surface area of whole cube / cm 2 Volume of cube / cm 3 Ratio of surface area to volume (χ:1) 1 6 2 24 3 54 4 96 5 150 6 216

5. Length of edge of cube / cm Surface area of whole cube / cm 2 Volume of cube / cm 3 Ratio of surface area to volume (χ:1) 1 61 2 24 8 3 54 27 4 96 64 5 150 125 6 216

6. Length of edge of cube / cm Surface area of whole cube / cm 2 Volume of cube / cm 3 Ratio of surface area to volume 1 61 6 2 24 8 3 3 54 27 2 4 96 64 1.5 5 150 125 1.2 6 216 1

7. Features of Specialised Exchange Surfaces. Large SA:Vol – increase rate of exchange Very thin – diffusion distance is short Partially permeable – allows selected materials to cross unobstructed Movement of environmental medium (air/water) – maintains diffusion gradient Movement of internal medium (blood) – to maintain diffusion gradient

8. Fick’s Law Diffusion∞ surface area x diff. in conc. length of diffusion path