A4.2 Conservation of biodiversity. Practice questions with markscheme.

• A: the moa (hunted to extinction after human arrival in New Zealand) represents lost terrestrial megafauna; the monk seal (hunted for oil, declared extinct 2008) represents a lost marine mammal;

• A: ex situ = conservation outside the natural habitat (zoos, botanic gardens, seed/gene banks); the others are in situ approaches;

• fossils can be counted in rocks of known age, giving the number of (marine) taxa / families present at different times;
• the number of taxa has increased over geological time, although not steadily;
• mass extinctions caused temporary falls, but diversity recovered and rose higher than before each time, OWTTE;
• the most recent rocks contain more taxa than rocks from any earlier period;
• the number of species alive today (described plus estimated undescribed) exceeds any estimate for the past;

Accept a reference to the fossil record being incomplete or to recent rocks being better preserved as a qualification, but it is not required.

• more people need more food, so land is cleared for agriculture / deforestation destroys natural habitat;
• the growth of towns and cities (urbanization) destroys and fragments habitats;
• greater demand for resources leads to over-exploitation / overfishing / hunting / logging of wild species;
• more production and consumption generate more pollution (including greenhouse gases), which damages habitats and species, OWTTE;
• more global transport and trade spread pests, diseases and invasive alien species to new areas;

• evolutionarily distinct species have few close relatives, so their extinction would lose a (disproportionately) large amount of unique evolutionary history/biodiversity;
• globally endangered means the risk of that loss is imminent;
• (resources are limited, so) combining the two criteria directs effort where the most irreplaceable diversity is at greatest risk, OWTTE;

• genetic diversity provides the variation on which natural selection acts;
• (so) the species can adapt to changing conditions / new diseases;
• low diversity increases inbreeding / vulnerability (a single threat can affect all individuals), OWTTE;

• named extinct species, e.g. North Island giant moa / Caribbean monk seal / dodo / passenger pigeon;
• cause(s) linked to humans: overhunting/overharvesting;
• and/or habitat destruction / introduced predators (rats, dogs) accompanying humans;
• extinction followed within a (relatively) short time of human contact/exploitation, OWTTE;

Any reasonable, factually correct example is acceptable.

• (a) [2]
  • Σn(n − 1) = 7140 + 56 + 12 + 2 + 0 = 7210;
  • D = (100 × 99) ÷ 7210 = 9900 ÷ 7210 = 1.37;
• (b) [2 max]
  • site P;
  • P has the higher Simpson reciprocal index (2.71 against 1.37) and a higher value indicates greater diversity;
  • although Q is richer in families, 85 % of its individuals belong to one family, so its evenness is very low;
  • the index combines richness with evenness, whereas a count of families uses richness alone;
• (c) [2 max]
  • one survey shows a state, not a change; surveys must be repeated over time before any trend can be claimed;
  • a single sample may be unrepresentative of the site as a whole and is likely to miss rare families;
  • invertebrates that avoid the net, or that live buried in the sediment, are not sampled, so the counts record only what the method can catch, OWTTE;
  • with one sample per site no measure of variability can be calculated, so it cannot be said whether the difference is significant;
• (d) [1 max]
  • genetic diversity (within a species);
  • ecosystem diversity (the variety of habitats/ecosystems present);