Classification Flashcards
Define phylogeny
The study of evolutionary relationships between organisms
Define taxonomy
The study of principles of classification
Explain the relationship between classification and phylogeny
Closely related species are placed in groups together. By knowing the relationship between species, one can put them in the correct group
describe the classification of species into the taxonomic hierarchy
domain, kingdom, phylum, class, order, family, genus and species
Dirty kinky people come over for group sex
Species are the basic unit of classification. All of the members show some variation, but are essentially the same.
As you rise through the ranks of taxa, the individuals grouped together show more and more diversity. There are fewer similarities and the individuals are less closely related.
What are the five kingdoms?
Prokaryotae, protoctista, fungi, plantae, animalia
Describe the features of prokaryotae
No nucleus
Loop of naked DNA
No Chromosomes
No membrane-bound organelles
Smaller ribosomes
Carry out respiration in mesosomes
Smaller cells
May be free living or parasitic
Describe the features of protoctista
Eukaryotes
Mostly single celled
Show a wide variety of forms
Show various plant-like or animal-like features
Mostly free living
Have autotrophic or heterotrophic nutrition
Describe the features of fungi
Eukaryotes
Have mycelium which consists of hyphae
Walls made of chitin
Cytoplasm is multinucleate
Mostly free living and saprophytic
Describe the features of plantae
Eukaryotes
Multicellular
Cells surrounded by a cellulose cell wall
Produce multicellular embryos from fertilised eggs
Autotrophic nutrition
Describe the features of animalia
Eukaryotes
Multicellular
Heterotrophic nutrition
Have fertilised eggs that develop into balls of cells called blastula Usually able to move around
outline the binomial system of nomenclature and the use of scientific (Latin) names for species
The binomial system is in Latin, which avoids any confusion caused by using common names, which can be different in different countries. The organism is given two names- the Genus and the Species name, e.g. Homo sapiens- Homo is the genus and sapiens is the species.
use a dichotomous key to identify a group of at least six plants, animals or microorganisms
A dichotomous key is a way of identifying and naming a specimen. The key provides a series of questions which have two answers, usually ‘yes’ or ‘no’. The answer to each question leads you to another question. Eventually the answers will lead you to the name of the species. A good dichotomous key has one less question than the number of species it can identify
What were classification systems originally based on?
Originally the classification systems were based on observable features
single celled organisms with animal-like features were classed as animals, and those that had features similar to plants were classified as plants.
But microscopes showed that some single celled organisms act like plants AND animals- Euglena photosynthesise and move, and Fungi do not move, but don’t photosynthesise either.
Molecular evidence, cytochrome c in respiration, embryological evidence with early development, fossil records for phylogeny.
In the end, the system was overhauled and ended up with the 5 kingdom classification of today.
What evidence do we now use to clarify relationships between organisms?
Biochemistry can also be used to show the evolutionary relationship between two species- depending the relationship between them, biochemical molecules, such as their DNA, will have evolved differently- Human DNA is more similar to a Monkey’s than to a mushroom’s. This allows organisms to be classified according to their genetics.
compare and contrast the five kingdom and three domain classification systems
The 3 domain system
Bacteria, archaea, eukarya
Based on differences in DNA
More accurately reflects origins of prokaryotes/eukaryotes
Domain divides prokaryotes (based on cell wall/ membrane/ flagella/ ATPase and DNA replication differences)
Domain groups eukaryotes together, reflects similarities between eukaryotic kingdoms (nuclei, membrane bound organelles)
