Classification Flashcards
Define classification
The act of arranging organisms into groups based on their similarities and differences
Why do we classify organisms?
To make it easier to identify them and study them
Taxonomy definition
The study of classification
How do classification systems work?
By placing organisms into a taxonomic heirarchy
What are the 8 levels of taxonomic groups? (in order)
-Domain
-Kingdom
-Phylum
-Class
-Order
-Family
-Genus
-Species
Keep Pond Clean Or Frog Gets Sick
What happens to the groups as you move down the heirarchy?
There are more groups but fewer organisms in each group
What are the 5 kingdoms in the five kingdom classification system?
- Prokaryotae
- Protoctista
- Fungi
- Plantae
- Animalia
What are the general features of the Prokaryotae group?
- Prokaryotic
- Unicellular
- No nucleus
- Less than 5 nanometers
What are the general features of the Protoctista group?
- Eukaryotic cells
- Usually live in water
- Single celled or simple multicellular organisms
General features of the Fungi group
- Eukaryotic cells
- Chitin cell wall
- Saprotrophic
- Single celled or multicellular organisms
Define saprotrophic
-Can absorb substances from dead or decaying organisms
General features of Plantae group
- Eukaryotic cells
- Multicellular
- Cell walls made of cellulose
- Can photosynthesise
- Contain chlorophyll
- Autotrophic
General features of Animalia group
- Eukaryotic
- Multicellular
- No cell walls
- Heterotrophic
What is the naming system used for classification called?
The binomial system
How does the binomial naming system work?
- The first part of the name is the genus name, and has a capital letter
- The second part of the name is the species, written with a lower case letter
- Names are always written in italics
Why is the binomial system used?
-To help avoid the confusion of using common names, e.g. over 100 different species are called raspberries
What is phylogeny?
The study of the evolutionary history of groups of organisms. Tells us who’s related to whom and how closely
What have all organisms evolved from?
A shared common ancestor
How can the relationship between organisms be shown?
Phylogenetic tree
On a phylogenetic tree, how can you tell species are closely related?
How reacently they divereged away from each other e.g. closely related species diverge away from each other most recently
Cladistics
The method of classifying organisms and taking into account phylogeny when arranging into groups
What was early classification based on?
Observational features
What is the problem with classifying based purely on observational features?
Scientists don’t always agree on the relative importance of different features and physical features alone may not show how closely related organisms are
What are the types of evidence that we now use to classify organism?
- Molecular evidence
- Embryological evidence
- Anatomical evidence
- Behavioural evidence
Describe molecular evidence for classification
- The similarities in proteins and DNA
- More closely related organisms will have more similar molecules
- Can compare how DNA is stored, sequence of the bases
- Can compare sequence of amino acids in proteins
How closely related are human and chimpanzee DNA?
94% the same
Cytochrome C
- A protein used in the process of respiration
- All living things that respire must have it
- Not identical in all species
How can cytochrome c be used to identify how closely species are related?
By identifying and comparing the amino acids in cytochrome c
- If the sequences are the same=closely related
- The more differences between the sequences the less closely related the species
Describe embryological evidence for classification
The similarities in early stages of an organisms development
Describe anatomical evidencs for classification
The similarities in structure and function of different body parts
Describe structural evidence for classification
The similarities in behaviour and social organisation of organisms
What can new technology do for classification?
Can result in new discoveries being made and relationships between organisms being clarifyed
What are the 3 domains?
- Eukarya
- Archaea
- Bacteria
Which kingdom split to create what 2 domains?
Prokaryotae split to create Archaea and Bacteria
What do organisms need to have to be in the kingdom of Eukarya?
A nucleus
Why was the three domains system proposed?
Because of new molecular evidence that showed large differences between Archaea and Bacteria
What was the evidence that changed the 5 kingdome system?
- Molecular evidence that the enzyme RNA polymerase is different in Bacteria and Archaea. Archaea, but not bacteria, have similar histones to Eukarya
- Cell membrane evidence that the bonds of lipids in cell membranes of bacteria and Archaea are different, the development and composition of flagellae are also different
What is the domain Archaea more closely related to?
-Eukarya
Define Variation
The differences that exisit between individuals. Even clones show some variation
What are the 2 types of variation?
Intraspecific variation and interspecific variaton
Define intraspecific variation
Variation within species.
Define interspecific variation
Variation between species
