| Date | May 2011 | Marks available | 1 | Reference code | 11M.3.hl.TZ2.B4 |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | State | Question number | B4 | Adapted from | N/A |
Question
DNA and RNA both contain a pentose sugar.
State the names of the sugars in each nucleic acid and outline how their chemical structures differ.
State one other structural difference between DNA and RNA.
Markscheme
ribose (in RNA) and deoxyribose (in DNA);
deoxyribose lacks an oxygen atom (on C2) / ribose has an OH group on second carbon in ring while deoxyribose has only H;
DNA contains thymine and RNA contains uracil / DNA is a double-strand
nucleic acid and RNA is a single-strand nucleic acid / OWTTE;
Examiners report
Knowledge of RNA and DNA was generally good. DNA profiling was something most students were familiar with, though some had troubles indicating the stages of the process and few candidates recognized that DNA fragments are negatively charged. The use of DNA profiling presented no problem.
Knowledge of RNA and DNA was generally good. DNA profiling was something most students were familiar with, though some had troubles indicating the stages of the process and few candidates recognized that DNA fragments are negatively charged. The use of DNA profiling presented no problem.
