Scientists grow animal cells in a liquid containing dissolved oxygen. The oxygen diffuses into each cluster of cells through the outer surface.
The same total volume of cells is grown in two different arrangements.
| Arrangement | Number of clusters | Total outer surface area in mm2 | Total volume in mm3 | Greatest distance from the liquid to the centre of a cluster in mm | Surface area to volume ratio |
|---|---|---|---|---|---|
| A: one large spherical cluster | 1 | 2.01 | 0.268 | 0.400 | 7.5 : 1 |
| B: smaller spherical clusters | 8 | 4.02 | 0.268 | 0.200 | to be calculated |
To calculate a surface area to volume ratio, divide the total outer surface area by the total volume.
Calculate how much outer surface area is available in arrangement B for every 1 mm3 of cells. Write the result as a surface area to volume ratio.
Explain why the cells in arrangement B can be supplied with oxygen more quickly than the cells in arrangement A.
Use the surface area to volume ratios and the greatest diffusion distances in your answer.
Cells inside a human organ are supplied by a network of capillaries rather than by blood flowing only around the outside of the organ.
Suggest one advantage of this network.
304 exam-style questions on AQA GCSE Biology 2.2 Animal tissues, organs and organ systems, covering 2.2.1 The human digestive system, 2.2.2 The heart and blood vessels, 2.2.3 Blood, 2.2.4 Coronary heart disease: a non-communicable disease, 2.2.5 Health issues, 2.2.6 The effect of lifestyle on some non-communicable diseases, and 2.2.7 Cancer. Each one has a worked solution and a mark scheme showing where the marks go.