Topic 3: Classification and biodiversity

order of the classifaction systems trophic levels

domain → kingdom → phylum→ class→ origin→ family→ genus→ species

morphology

The physical form and structure of an organism's internal and external body parts

Homologous structures

Body parts in a different species that are physically similar even if they have different functions Shows common ancestry Example: pentadactyl limb shared by humans and bats

Aristotle

1st Scientist to classify things Put living things into groups by morphology Animals- land, sea, sky Plants- big, medium, small

Analogous features

features that look similar/ have the same function but not the same biological origin

how are organelles classified

• based on characteristics and evolutionary relationships

• more specific down the hierarchy

definition of a species

group of organisms with similar characteristics that can be bred to produce fertile offspring

limitations of the definition of a species

• asexual organisms cant be bred

• fossils cant be tested is they can interbred

• isolated organisms cannot interbreed

why classification can be difficult

• hard to see if a new organism is a new species or fits into an existing one

• similar appearance, physically different but same species, look similar but genetically different, hybridisation or asexual reproduction

what is hybridisation

different species interbreeding