5. Classification of Biodiversity Flashcards
What is ‘classification’ in biology?
the process of putting species of living organisms into groups
Why is ‘classification’ an essential process in biology?
there are so many species and without a classification system it would be very hard to store and access information about them
What are biologists that specialise in classification called?
taxonomists
How many ways of classifying organisms are there?
‘many possible ways’
What is an artificial classification? Give an example of an artificial classification.
when animals are not similar enough to be grouped together in other ways:
e. g. those that have wings and those that do not:
- that would encompass insects, birds and bats
- but even their wing structure is not homologous and has evolved separately
What is the opposite of artificial classification?
natural classification
What is natural classification? What will species that have been classified through natural classification all have in common?
classification in which the species in a group have evolved from one common ancestral species
- one common ancestral species: therefore they will share many characteristics that they have inherited from the ancestral species
What does natural classification allow taxonomists to do? What does it also help with?
- allows the prediction of characteristics shared by species within a group
- help in identification of species
Is natural classification obvious? Why?
- no
- not always clear what the pattern of evolution was in a group of species
When might taxonomists reclassify a species?
when new evidence shows that a previous taxon contains species that have evolved from different ancestral species
Give an example of taxonomists reclassifying a species.
‘five kingdoms system’ developed in second half of the 20th century:
- all prokaryotes in one kingdom
- eukaryotes in four kingdoms
HOWEVER,
when the base sequence of nucleic acids was compared, two very different groups of prokaryotes were identified
SO
a higher grade of taxonomic group was needed to reflect this, now called a ‘domain’
All current organisms are currently classified into how many domains? Name all of them.
3 domains:
- Archea (referred to as archaeans)
- Eubacteria (referred to as bacteria)
- Eukaryota (referred to as eukaryotes)
What is the original evidence that obliged scientists to classify all organisms within the current three domains? What does this evidence suggest?
base sequences of ribosomal RNA:
- found in all organisms and evolves slowly
- so it is suitable for studying the earliest evolutionary
events
suggests that prokaryotes diverged into Eubacteria and Archaea early in the evolution of life, so it is not appropriate to classify them together in one kingdom
Where are viruses classified? Why?
- not classified into any domains nor are they classified into a domain of their own
- not considered by biologists to be living organisms
Define ‘taxon’.
a group of organisms, such as a species or a genus
What is a ‘taxa’.
- plural of taxon
- a series of taxons (you’ll see an example in later cards in this deck or on page68)
What is the ‘hierarchy of taxa’.
a series of taxa, each of which includes a wider range of species than the previous one
How are similar species grouped?
into a genus
How are similar genera grouped?
into a family
How are similar families grouped?
into an order
How are similar orders grouped?
into a class
How are similar classes grouped?
into a phylum
How are similar phula grouped?
into a kingdom
How are similar kingdoms grouped?
into a domain
You don’t need to learn this!
Here is the hierarchy of taxa for a blue whale:
Animal: Balaenoptera musculus Genus: Balaenoptera Family: Balaenopteridae Order: Cetacea Class: Mammalia Phylum: Chordata Kingdom: Animalia Domain: Eukaryota
