Cells are grown inside a capsule. Oxygen diffuses through the permeable wall of the capsule.
Four redesigns of the capsule wall are tested. The table shows each redesign compared with the original capsule.
| Redesign | Surface area | Wall thickness |
|---|---|---|
| W | halved | halved |
| X | unchanged | doubled |
| Y | halved | doubled |
| Z | doubled | halved |
For one redesign, the diffusion rate is one quarter of the original rate. The concentration difference and all other factors remain constant.
Using Fick's law, which redesign gives this diffusion rate?
Redesign X
Redesign Y
Redesign Z
Redesign W
102 exam-style questions on Edexcel GCSE Biology 8.1 Exchange surfaces and diffusion, covering 8.1.1 Introduction to exchange and transport, 8.1.2 Alveoli adapted for gas exchange, 8.1.3 Factors affecting rate of diffusion, and 8.1.4 Rate of diffusion using Fick's law. Each one has a worked solution and a mark scheme showing where the marks go.