Classification Flashcards
Biological Classification
Classification is based on the idea that members of the same group share characteristics that are not present in members outside the group.
What is Taxonomy?
The study of classification
Why classify?
- Provides methods of sorting, so that similar or related organisms are grouped together
- See patterns and trends to better understand relationships between organisms
- Allow biologists to analyse information about organisms (data collection, comparison, evaluation)
- Allows biologists to communicate with one another
Levels of Classification
Domain
Kingdom
Phylum (Phyla)
Class
Order
Family
Genus
Species
Three Domains
Eukarya, Archaebacteria and Bacteria
What are the features of eukaryotes? (Containing Domain Eukarya)
Contains DNA with a nucleus and membrane bound organelles
What are the features of prokaryotes? (With domains and Kingdoms Archae and Bacteria)
No nucleus or membrane bound organelles
Binomial naming
A binomial name consists of two parts:
- a generic name (genus) and
- A specific name (species sometimes name of person who found the organism)
Physical characteristics to classify
Morphology is used to classify organisms with similar physical features together. For example dogs can be classified using colour and size.
Methods of Reproduction to classify - Among Mammals?
This aims to classify organisms using asexual (without production of gametes) and sexual reproduction (mixing of gametes) and their specific methods of reproduction and whether they lay eggs or give birth live or have specific structures (e.g. placenta).
Mammals:
Eutherian (placental) mammals: give birth to live young after gestation (inside the mother)
Marsupials: give birth to live young at very early developmental stage. Then develop in a pouch on the belly of the mother until mature enough to survive outside
Monotremes: lay eggs
Molecular Sequence to classify
DNA and Protein sequences are used to put a signification to the relationships between species
DNA - Looks at base sequencing.
Protein - Looks at amino acid sequencing
What Kingdoms does the Eukarya Domain Include
Animalia, Plantae, Protista and Fungi
What Domain and Kingdom names do prokaryotes include?
Archae and Bacteria
What does Protista include?
Includes
amoebae
What are Archae?
Microscopic
single-celled
organisms
known for
living in extreme
environments
Why classify organisms?
Invasive Species?
Better understand relationships between organisms
Allow biologists to analyse/research information about organisms
The third reason is that classifying organisms allows biologists to communicate with one another.
Finally, classification means invasive species can be identified more easily and accurately
Porifera Example and Characteristics
Sponges
Asymmetrical (no definite symmetry)
Body is multicellular, with few tissues and no
organs
Cells and tissues surround a water-filled space
but there is no true body cavity
All are sessile (as an adult, live attached to
something)
Reproduce sexually or asexually
Cnidaria Examples and Characteristics
Jellyfish, sea anemones and corals
Radially symmetrical (body plan is circular with
structures that radiate out)
Gastrovascular cavity with single opening that
serves as both mouth and anus
Reproduce sexually or asexually
Simple, net-like nervous system
Live in aquatic environments, mostly marine
Platyhelminthes Example and Characteristics
Flatwroms
Bilaterally symmetrical (left and right halves of
body are mirror images)
Gastrovascular cavity with single opening that
serves as both mouth and anus
Body has three layers of tissues, with organs
Body without cavity
Body has blind gut (mouth but no anus)
Flattened body shape
Mollusca Example and Characteristics
Molluscs
Biterally symmetrical
Body without cavity
Body has through gut (with mouth and anus)
Uses muscular foot for locomotion
Open circulatory system with heart and aorta
Annelida Example and Characteristics
Earthworms
Bilaterally symmetrical
Body has more than two cell layers, tissues and
organs
Body cavity, nervous system and closed
circulatory system
Body has through gut (with mouth and anus)
Nematoda Example and Characteristics
Roundworms
Bilaterally symmetrical
Cylindrical morphology
Body covered by tough cuticle (of collagen and
chitin)
Alimentary canal (digestive system) with mouth
and anus, but no circulatory system
Found in most aquatic habitats, soil, moist
tissues of plants, and body fluids and tissues of animals
Arthropoda
Scorpions
Usually bilaterally symmetrical
Segmented
Hard exoskeleton (external skeleton) of protein and chitin
Most have through gut (with mouth and anus)
Jointed appendages (body parts attached to
main trunk such as arms, legs, wings); have
3–400+ pairs of jointed legs
Echinodermata Example and Characteristics
Starfish
1 Five-rayed symmetry, mostly radial, sometimes
bilateral
2 Body has more than two cell layers, tissues and
organs
3 Thin epidermis covering an endoskeleton; most
species prickly due to skeletal bumps and spines
4 Most have short, through gut (with mouth and
anus)
5 Body shape highly variable, but with no head
Chordata Example and Description
1 Ninety per cent are vertebrates (have
backbones), but Chordata does include two
invertebrate groups
2 Have the following features during development
(possibly as embryo): * pharyngeal slits: series of openings
connecting inside of throat to outside of
‘neck’; often, but not always, used as gills
* dorsal nerve cord: bundle of nerve fibres
running down the ‘back’; connects brain with
lateral muscles and other organs
* notochord: cartilaginous rod running
underneath nerve cord
* post-anal tail
3 Closed circulatory system with blood
transported in arteries, veins and capillaries
4 Bilaterally symmetrical
What are characteristics of dichotomous keys
Dichotomous keys are tools used to identify organisms.
They involve choosing between a series of two options until an organism is identified. Yes or no questions which decide options
Cladistics
Organisms are classified into groups that reflect their evolutionary history.
This classification is based on the fact that related organisms share Physical characteristics.
Phylogenetic trees made using this technique are known as cladograms.
Cladistical Assumptions
The more closely related two organisms are, the more characteristics they will share.
Some characteristics that are shared by a group will not be present in more distantly related groups.
When there are multiple possible ways that organisms can be related, the simplest explanation is the most likely to be correct. This is because if a feature is shared between organisms, it is more likely that this feature evolved once in a common ancestor than independently for each organism.
What is a character matrix?
Allows for + - to show if a group/s has one/many specific characteristics. Tabulate
DNA technology impact
Supports previous classification or reclassifies of organisms
Provides clarity as to when certain groups evolved
Allows classification down to many more levels than the traditionally recognised taxa; i.e. prefixes super- (above) and sub- (below) - additional ranks (e.g. subphylum) and some newer taxa (e.g. tribe)
