Surface area and Volume PAG

Question 1

Explain…

Answer 1

As SA:V increases the rate of diffusion increases as smaller organisms have a larger SA:V which ensures efficient delivery of glucose and oxygen to cells whereas larger organisms have a smaller SA:V so the diffusion distance is too long and therefore diffusion is too slow to meet the needs of the organism.

Question 2

Limitations of experiment

Answer 2

Subjective when colour change of cube has completed
agar cube stuck to side of the cube means not all SA in contact with acid
cubes have no membrane so do not model diffusion
cubes do not represent shapes of living organisms

Question 3

Errors of experiment

Answer 3

might not stop stopwatch at the exact time of colour change or start stopwatch at exact time acid is added to cube
volume of acid incorrectly measured
size of cube incorrectly measured

Question 4

How to make the experiment more repeatable and reproducible

Answer 4

Use a mould to cut agar cubes and ensure a minimum of 3 repeats to reduce the effect of anomalies
Use the same mould to cut agar cubes