| Date | May 2015 | Marks available | 2 | Reference code | 15M.3.hl.TZ2.11 |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | Outline | Question number | 11 | Adapted from | N/A |
Question
Deoxyribonucleic acid (DNA) is the genetic material that an individual inherits from both parents. DNA consists of nucleotides bonded together.
Outline the essential features of the structure of a section of one strand of DNA.
Markscheme
(backbone of) sugar-phosphate;
nitrogenous bases attached to sugar;
four (different) nitrogenous bases / C, T, A and G;
sugar is a pentose;
Examiners report
Many students discussed the structure of DNA as a whole rather than that of a single strand, as requested in the question. Nevertheless in the course of this many gave enough detail to gain some credit. The role of restriction enzymes and the polymerase chain reaction seemed well known, though the order of these was less clear. Details of the separation and detection of the fragments were however often less accurate. A significant minority of students attempting this question displayed some confusion with proteins and the electrophoresis of their component amino acids.
