DP Biology (first assessment 2025)

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Question 23M.2.SL.TZ2.21

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Date May 2023 Marks available [Maximum mark: 6] Reference code 23M.2.SL.TZ2.21
Level SL Paper 2 Time zone TZ2
Command term Explain Question number 21 Adapted from N/A
21.
[Maximum mark: 6]
23M.2.SL.TZ2.21

Explain how biogeographic factors affect the richness and evenness of biodiversity.

[6]

Markscheme
  1. biogeographic features are combinations of species, habitats and physical features;
  2. richness is the number of different species present (in an area);
  3. evenness refers to relative abundance of the different species (in an area) /OWTTE;
  4. large nature reserves/large islands (potentially) have greater biodiversity /richness / evenness;
  5. large areas (tend to) have more species/populations/habitats/richness
    OR
    large areas have more stability/higher biodiversity index
    OR
    have less chances of loss of a species;
  6. connected areas/nature reserves have more diversity than isolated ones
    OR
    corridors between (small) areas/ reserves increases richness/biodiversity;
  7. the greater the surface:perimeter ratio, the greater the biodiversity;
  8. edges are transition areas
    OR
    have greater richness/lower evenness
    OR
    are less stable;
  9. circular shape has more biodiversity than rectangular shape;
  10. biodiversity measured by Simpson’s / diversity index;
  11. one additional abiotic factor affecting biodiversity;

 e.g. precipitation, soil quality/content, temperature, etc.

Syllabus sections