Q32 (b)

Criteria	Marks
• Uses a cause-and-effect statement to explain how it acts as a mutagen.	2
• Identifies how it acts as a mutagen, OR identifies a process that changes cell expression, OR defines a mutagen.	1

Additional guidance from the source:

a piece of its own DNA (from a plasmid) into a plant chromosome. This is a change to the sequence of base pairs, is (semi) permanent for infected cells, i.e. a mutation. This can be seen by the change in expression of those cells as they form a tumour. Range: 0-2; Average: 1.2 Comments: The verb in this question was explain, which is most easily answered with a cause and effect structure. A number of students did not link a cause and effect so were unable to access all the marks, in particular they did not show how the DNA was changed. In general, do not use stimulus from later in the question to answer an earlier part. A couple of misconceptions included: different proteins produced causing the mutation (it is a result of the mutation), the tumour causes the mutation (the mutation causes rapid growth of undifferentiated tissue).