A marker gene can be used when a gene of interest is introduced into a plant by genetic engineering.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2023). The mark or mark type is shown in brackets.

1. [1] (a) marker gene added with gene of interest (GOI) ;
2. [1] (a) use same promoter ;
3. [1] (a) (so) both genes, transcribed / expressed (together) ;
4. [1] (a) (so) both proteins are produced;
5. [1] (a) use UV light (to detect fluorescence) ;
6. [1] (a) fluorescence shows, transcription / expression, of gene of interest (GOI) ;
7. [1] (a) AVP; e.g. fluorescent proteins not harmful / have no effect on plant/ do not affect quantity of desired protein produced
8. [1] (b) high/increase in, yield / productivity / quality or more food;
9. [1] (b) increased income / reduce costs ;
10. [1] (b) can use herbicides / AW;
11. [1] (b) less/no, competition;
12. [1] (b) no need to plough / less labour intensive ;
13. [1] (c)(i) complementary (base pairing between DNA strands) / described ;
14. [1] (c)(ii) use mRNA to make (ss)cDNA ;
15. [1] (c)(ii) fluorescent, tag / dye / substance / label, attached to cDNA;
16. [1] (c)(ii) hybridisation / binding, of cDNA to probe ;
17. [1] (c)(ii) use, lasers / UV light, to produce fluorescence ;
18. [1] (c)(ii) idea of intensity of, fluorescence / light, indicates level of (gene) expression;