Date | May 2011 | Marks available | 2 | Reference code | 11M.3.hl.TZ1.B5 |
Level | HL | Paper | 3 | Time zone | TZ1 |
Command term | Identify | Question number | B5 | Adapted from | N/A |
Question
In aerobic respiration, the metabolism of glucose takes place using the processes of oxidation and reduction.
Identify the molecule that undergoes oxidation and state the half-equation for the process.
Identify the molecule that undergoes reduction and state the half-equation for the process.
Markscheme
glucose/\({{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}\);
\({{\text{C}}_6}{{\text{H}}_{12}}{{\text{O}}_6} + {\text{6}}{{\text{H}}_2}{\text{O}} \to {\text{6C}}{{\text{O}}_2} + {\text{24}}{{\text{H}}^ + } + {\text{24}}{{\text{e}}^ - }\);
oxygen/\({{\text{O}}_{\text{2}}}\);
\({\text{6}}{{\text{O}}_2} + {\text{24}}{{\text{H}}^ + } + {\text{24}}{{\text{e}}^ - } \to {\text{12}}{{\text{H}}_2}{\text{O}}\);
Accept equation divided by 6.
Award [2 max] if (a) and (b) are reversed and all 4 marking points are correct.
Examiners report
Majority of candidates identified that glucose was oxidised and oxygen was reduced.
It was very rare to see correct half-equations.