11 Classification Flashcards
(12 cards)
Classification
is the way in which living organisms are divided into groups
Taxonomy
is the scientific practice of grouping organisms based on shared characteristics
Modern classification systems are also:
· Hierarchical
This means that the system consists of:
- smaller groups within larger groups
- no overlap between groups.
· Phylogenetic.
This means the system is based on the evolutionary history of organisms, i.e. their common ancestry.
Hierarchical System
· Domain
· Kingdom
· Phylum (pl. = phyla)
· Class
· Order
· Family
· Genus (pl. = genera)
· Species
§ Did King Phillip Come Over For German Sausages?
The biological name
· The first is the genus name and always has a capital letter
· The second is the species name and always has a small letter
Phylogenetic system
· This shows the evolutionary relationship between organisms.
· It looks at similarities and differences in structure and function.
- · The closer the branches, the closer the evolutionary relationship, therefore the more recently they shared a common ancestor
Species
A group of organisms with similar characteristics that can interbreed to produce fertile offspring
Problems in classifying organisms as distinct species
· Most species did not leave fossils and even when fossils have been found, they are often incomplete and not all features can be observed.
Courtship Behaviour
Courtship behaviour is used to identify individuals as members of the same or different species.
- Only members of the same species can produce fertile offspring.
Courtship behaviour has a number of different functions which include:
Species recognition Allows one member of a species to recognise other members of the same species. This ensures they only mate with individuals from the same species so fertile offspring are produced.
Formation of a pair bond This keeps the male and female together which increases the survival chances of the offspring
Synchronising mating This identifies when individuals are at the correct stage of their reproductive cycle so mating only occurs when there is the maximum probability of egg and sperm meeting.
Stimulating production of gametes
Stimulates production/release of gametes.
Identifying a mate that is sexually
mature Prevents mating with a sexually immature individual which doesn’t produce gametes.
Different ways of investigating genetic diversity and looking for evolutionary relationships between species include:
The base sequence of DNA
- The base sequence of mRNA
- The amino acid sequence of the proteins encoded by DNA and mRNA
Samples may need to be taken. They should be:
· Large – large samples are more representative of the population than small samples and minimise the influence of chance on the results.
· Random - this avoids bias and ensures that every member of the population has an equal chance of being included in the sample
