CAIE A Level Biology 9700 · Nucleic acids and protein synthesis
The table below shows the percentages of the four nitrogenous bases in a sample of bacterial DNA.
| Base | Percentage |
|---|---|
| Adenine | 28 |
| Thymine | 28 |
| Guanine | 22 |
| Cytosine | 22 |
Describe the structure of DNA, using the data in the table to explain how complementary base pairing occurs.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.