| Date | November 2011 | Marks available | 2 | Reference code | 11N.3.SL.TZ0.7 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Compare | Question number | 7 | Adapted from | N/A |
Question
The table below shows the results of continuous stimulation of the tailshaker muscle of eight western diamond rattlesnakes (Crotalus atrox).
Using the graph, measure the amount of ATP produced by oxidative phosphorylation, giving the units.
Compare the changes in oxygen and lactate content in the blood when a resting rattlesnake starts rattling.
Using the data, deduce, with reasons, whether anaerobic respiration provides some or all of the ATP used in rattling.
Markscheme
0.8 m mol dm -3 s -1 (allow responses in the range of 0.7 m mol dm -3 s -1 to 0.8 m mol dm-3 s-1)
small/insignificant increase in oxygen;
much larger increase in lactate;
some ATP provided by anaerobic respiration because lactate levels rise;
ATP production by glycolysis is high/about 50 % of ATP demand;
ATP also provided by oxidative phosphorylation in aerobic respiration;
sample number too low to make definite conclusion;
Examiners report
Candidates were able to correctly use the graph to find the amount of ATP produced by oxidative phosphorylation.
Most saw that there was a much larger increase in lactate than in oxygen content during rattling.
Many candidates did poorly on this question which required them to use the data to deduce the role of anaerobic respiration in provision of ATP for rattling. Deduce is a command term that candidates find difficult. It requires them to use the data to reach a conclusion.
