Section B Answer one question. (a) Explain what is meant by the terms ecosystem and niche.

Mark scheme

Marking points from the official mark scheme (Feb/Mar 2017). The mark or mark type is shown in brackets.

1. [1] (a) seven from: ecosystem: 1 self-sustaining unit;
2. [1] (a) 2 self-contained/defined, area;
3. [1] (a) 3 community of organisms ;
4. [1] (a) 4 living and non-living/biotic and abiotic ;
5. [1] (a) 5 reference to, interactions/interdependence ;
6. [1] (a) 6 reference to, energy flow/food webs ;
7. [1] (a) niche: 7 role of organism/how it fits in, (in an ecosystem);
8. [1] (a) 8 (including) where it lives;
9. [1] (a) 9 how it obtains its energy/reference trophic level;
10. [1] (b) eight from: 1 random (sampling);
11. [1] (b) 2 (frame) quadrat ;
12. [1] (b) 3 use cover scale;
13. [1] (b) 4 estimate % cover;
14. [1] (b) 5 species frequency ;
15. [1] (b) 6 systematic sampling;
16. [1] (b) 7 line/belt, transect;
17. [1] (b) 8 sample at set distances;
18. [1] (b) 9 mark - release - recapture;
19. [1] (b) 10 method of, capture/marking;
20. [1] (b) 11 returned to habitat and left;
21. [1] (b) 12 population estimate = no of individuals in first sample × no of individuals in second sample no of individuals marked in second sample ;
22. [1] (b) 13 appropriate mathematical/statistical technique ;