Topic 4C: Diversity and Classification- Classification of organisms …
Topic 4C: Diversity and Classification- Classification of organisms
The evolutionary relationship of a group of organisms. This tells us who is related to whom and how closely related they are. Scientists take phylogeny into account when classifying organisms.
These present how organisms have diverged from common ancestors.
The first branch of a phylogenic tree represents a common ancestor of all family members. This ancestor is now extinct.
Closely related species will have diverged away from each other more recently.
Closely related organisms will have branches that are closer together.
All organisms have evolved from shared common ancestors
This refers to the science of classification
Taxonomy refers to the process of naming organisms and organising them into groups based on similarities and differences. This makes it easier for scientists to study them.
Organisms are grouped according to their evolutionary relationships
Taxa are the eight levels of groups used to classify organisms. These groups are organised into a hierarchy, with the largest group at the bottom and the smallest groups at the top. Organisms can only belong to one group at each level in the hierarchy, therefore resulting in no overlap. The eight levels of classification are:
-Species (contains only one group of organisms, such as humans)
As you move down this list, there are more groups at each level but fewer organisms belonging to each group.
Organisms are first ordered into domains. The three domains are:
A group of similar organisms that are able to reproduce to give fertile offspring.
The binomial system
This is the naming system used for classification
All organisms are given one internationally accepted name in latin. This name is composed of two parts:
The genus name (capital letter)
The species name (lower case)
-In an exam, these names should be underlined. Scientists would usually write these in
Assigning a scientific name to an organism is important because this allows scientists to communicate about organisms in a standard way and therefore avoids any confusions associated with their common name.
The classification system is being constantly updated by scientists because of the emergence of new discoveries about a new species and new information regarding an already known organism (their DNA sequence, for example).