A donor DNA molecule contains the required gene between positions 300 and 900. The table shows every cutting site for three restriction enzymes on this molecule.
Table
| Enzyme | Cutting positions |
|---|---|
| P | 200 and 1000 |
| Q | 200 and 600 |
| R | 600 and 1000 |
Each enzyme can also open the vector and produce compatible sticky ends.
Which enzyme should be used to remove a fragment containing the complete gene?
Q, because one cut lies before the required gene.
R, because one cut lies after the required gene.
Q and R, because their shared cut lies within the gene.
P, because both cuts lie outside the required gene.
44 exam-style questions on Edexcel GCSE Biology 4.3 Selective breeding and genetic modification, covering 4.3.1 Selective breeding and its impact, 4.3.2 Tissue culture, 4.3.3 Genetic engineering overview, 4.3.4 Main stages of genetic engineering, 4.3.5 Advantages and disadvantages of GM organisms, 4.3.6 Agricultural solutions for a growing population, and 4.3.7 Evaluating genetic engineering and breeding. Each one has a worked solution and a mark scheme showing where the marks go.