| Date | November 2016 | Marks available | 1 | Reference code | 16N.3.hl.TZ0.15 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | State | Question number | 15 | Adapted from | N/A |
Question
The structure of DNA (deoxyribonucleic acid) has been studied in many different ways.
State the name of the component of DNA responsible for the migration of its fragments to the positive electrode in gel electrophoresis.
In 2010, scientists claimed that they had discovered a species of bacteria capable of incorporating arsenic in place of phosphorus into the bacterial DNA. This claim has since proved controversial. Suggest one technique or evidence that might help support the claim.
Markscheme
phosphato/phosphate «group»
Do not accept “phosphoric acid”, “phosphorus” or any formula.
mass spectrometry / X ray diffraction/crystallography / nuclear magnetic resonance «spectroscopy»
OR
bacteria able to grow in absence of phosphorus
OR
reproducible data
Accept abbreviations (eg, MS, NMR).
Accept “elemental analysis” or “atomic absorption spectroscopy/AA(S)”.
