| Date | November 2009 | Marks available | 1 | Reference code | 09N.3.SL.TZ0.9 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | State | Question number | 9 | Adapted from | N/A |
Question
State the location of high proton concentration caused by electron transport in the mitochondrion.
Outline the role of oxygen in cellular respiration.
Explain how any two structural features of the mitochondrion are related to its function.
Markscheme
inter-membrane space / outside inner membrane / between outer and inner membrane
in the electron transport chain;
final electron/hydrogen acceptor;
combines with H+ (and electrons) to produce water;
cristae for increasing surface area;
small inter-membrane space for rapid build-up of concentration gradient;
matrix with chemical concentration to support unique chemical reactions;
Examiners report
Most candidates answered this question correctly.
Candidates failed to understand the role of oxygen in respiration. They explained how oxygen is necessary for aerobic respiration, but did not understand why.
The presence of cristae to increase surface area was among the most common correct answers regarding the features of mitochondria relating to their structure. Other features were hardly mentioned.
