Fruit flies of the genus Bactrocera are pests that damage fruit crops. Table 3.1 gives the names and geographical ranges of Bactrocera fruit flies that were classified as four separate species. [Table 3.1] In 2014, the classification of these flies was changed. All four species were recognised as belonging to a single species, B. dorsalis.

Mark scheme

Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.

1. [1] (a)(i) differences in, morphology / phenotype / characteristics;
2. [1] (a)(i) differences in, physiology / biochemistry;
3. [1] (a)(i) genetic differences / AW ;
4. [1] (a)(i) differences in behaviour ;
5. [1] (a)(i) differences in ecological niche ;
6. [1] (a)(i) isolated, populations / species or found in different geographical areas / AW or reproductively isolated / AW ;
7. [1] (a)(ii) mate them together ;
8. [1] (a)(ii) see if offspring can interbreed / see if offspring are fertile;
9. [1] (a)(ii) ref. to bioinformatics investigation / described ;
10. [1] (b) Fungi;
11. [1] (b) Protoctist(a);
12. [1] (b) Prokaryota(e) / Prokaryote; I bacteria
13. [1] (c) hard to control / may become invasive / AW ;
14. [1] (c) may lack predators;
15. [1] (c) may lack herbivores ;
16. [1] (c) may, prey on / parasitise, local/native, species / organisms;
17. [1] (c) may compete with, local / native, species / organisms; A description e.g. eat their food supply
18. [1] (c) may decrease, biodiversity / species richness / species abundance / AW ;
19. [1] (c) may have effects on, food web / ecosystem ;
20. [1] (c) may introduce diseases ;
21. [1] (d) ban on African fruit should be lifted;
22. [1] (d) can export more fruit / can export fruit to Asia / find new overseas markets ;
23. [1] (d) economic benefit / more work / more opportunities for farmers / social benefit ;