(a) One way to measure global biodiversity is to count the number of species of organisms. Table 3.1 shows estimates for 2009 of the number of species in some taxa of animals. The numbers in brackets are the numbers that were updated in 2019 from the International Union for Conservation of Nature and Natural Resources (IUCN) for three intensively studied taxa. [Table 3.1] (b) An analysis in 2019 concluded that twice as many insect species have populations that are decreasing in size compared with chordate species. This analysis focused on developed countries that have large human populations.

Mark scheme

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

1. [3] any three from: 1 multicellular; 2 have, specialised cells / tissues / organs ; 3 heterotrophic / described ; 4 ref. to nervous system ; 5 vacuoles / vesicles, are, small / temporary / not permanent ; 6 are eukaryotes / have eukaryotic cells ; 7 detail of eukaryote; e.g. nucleus / (named) membrane-bound organelle / 80s ribosomes 8 ref. to mobility;
2. [3] any three from: 1 records / assesses, biodiversity; 2 so conservation decisions can be made / AW; 3 example of conservation action 1; 4 example of conservation action 2; e.g. (IUCN) red list of threatened species / identifying endangered species (CITES) regulation of trade ref. assisted reproduction or ref. captive breeding seed banks place in, zoos / national parks / marine parks / botanical gardens 5 (taxonomic hierarchy is) internationally, recognised / standardised / AW ;
3. [2] any two from: 1 (yes because as number of species has increased) biodiversity has increased ; 2 (idea of no because) numbers of new species that are being discovered are greater than the numbers of species becoming extinct ; 3 (idea of no because) does not assess number of individuals in a species; 4 AVP; e.g. some species only exist in captivity
4. [2] insects 1024 945 / 1438 805 (×100) ; 71 ; ecf - accept 1 mark if wrong data chosen e.g. insects / arthropods 1024 945 / 1191770 (×100) = 86 arthropods / animals 1191770 / 1438 805 (×100) = 83
5. [2] any two from: 1 habitat loss / habitat fragmentation / urbanisation / building / deforestation ; 2 insecticides / pesticides / farming / agriculture / fertilizers ; I pollution 3 new / increase in, predators / diseases / parasites ; 4 food shortage / increased competition (for food);
6. [2] any two from: 1 Bt toxin (only) kills, specific insects / insects that feed on the crops ; 2 reduces use of, insecticides / pesticides; 3 idea that insects survive to pollinate plants ;