Classification and evolution- classification, the five kingdoms, phylogeny Flashcards
what is classification?
the process by which living organisms are sorted into groups. The organisms within each group share similar features.
what is taxonomy?
the practice of biological classification. This allows us to arrange species into taxonomic groups (taxa) based on their evolutionary origins and relationships.
what are the seven taxonomic groups?
kingdom, phylum (plural phyla), class, order, family, genus (plural genera) and species.
describe the kingdoms group
-biggest and broadest group
-least specific
Describe the species group
-smallest
-most specific
who first proposed the heirarchal classifications system?
Carl Linnaeus in the 18th century
what level of classification is placed at the top of the hierarchy?
the domain, based on recent studies of genetic material. As new scientific discoveries are being made, the current system of classification may change again
why do scientists classify organisms?
-to identify species
-to predict characteristics
-to find evolutionary links: common ancestor
what are the three domains?
archaea, bacteria and eukarya. These are the broadest groups
Describe the pattern as you go down the heirarchy from the broadest group (domain)
-As you go down, there are more groups at each level, but fewer organism in each group.
-the organisms in each group become more similar, sharing same characteristics
how does the heirarchal system end?
organisms become classified as individual species, smallest unit of classification. Each group contains only one type of organism.
what is a species?
group of organisms that are able to reproduce to produce fertile offspring
why are infertile offspring produced when two organisms of different species reproduce?
odd number of chromosomes produced so meiosis and gamete production cannot take place correctly as all chromosomes must pair up
humans belong to what species (scientific name for humans)?
Homo sapiens
Before classification, organisms were given names based on their physical characteristics. Why is this not useful?
-not usefully when working internationally as organisms may have more than one common name and in different languages
-does not provide information about relationships between organisms
How do scientists ensure they are discussing the same organism Internationally?
using binomial nomenclature system where binomials are the scientific names given to an individual species
binomials consist of an organism’s?
genus (first word) and species/specific name (second word) name
what is the genus?
name shared by close relatives
could two species have the same generic and species name?
no but they could have the same specific name but genus would be different
how is the binomials for a species written?
always in italics. Genus name should have capital letter but species name shouldn’t
what are the five kingdoms?
-prokaryotae (bacteria)
-protoctista (the unicellular eukaryotes)
-fungi (yeasts, moulds an mushrooms)
-plantae (the plants)
-animalia (the animals)
what are the general features of prokaryotae?
-unicellular
-no nucleus or membrane bound organelles.
-a ring of ‘naked’ DNA and small ribosomes
-no visible feeding mechanism: nutrients are absorbed through the cell wall or produced internally by photosynthesis
what are the general features of protoctista?
-(mainly) unicellular
- a nucleus and other membrane-bound organelles
-some have chloroplasts
-some are sessile, but others move by cilia, flagella or amoeboid mechanisms
-nutrients from photosynthesis (autotrophic feeders), ingestion of other organisms (heterotrophic feeders) or both- some are parasitic
what are the general features of fungi?
-unicellular or multicellular
-nucleus and membrane bound organelles and a cell wall mainly composed of chitin.
-no chloroplasts or chlorophyll
-no locomotion mechanism
-most have a body or mycelium made of threads or hyphae
-nutrients from absorption, mainly decaying material (saprophytic feeders). Some are parasitic.
-most store their food as glycogen
