4.2.2 - Classification and Evolution Flashcards
What is classification?
the process by which living organisms are sorted into groups based on similar features
Why are organisms classified?
- to identify species
- to predict characteristics
- to find evolutionary links
What is the taxonomic heirarchy?
(Domain) Kingdom Phylum Class Order Family Genus Species
What is a species?
a group of living organisms that can interbreed to produce fertile offspring
What is the binomial nomenculture?
method of naming species
- first name from genus
- second name from species
- must be written in italics (underlined in exam!)
- first letter must be capital
What are the advantages of binomial nomenculture?
- provides information about relationships between organisms
- species has the same name in all languages (unlike common names)
What are the five kingdoms?
Prokaryotae Protoctista Fungi Plantae Animalia
What are the features of the Prokaryotae kingdom?
- prokaryotes
- no nucleus (ring of DNA instead)
- absorbs nutrients through cell wall or produces them by photosynthesis
- cell wall made of peptidoglycan
- unicellular
- has small ribosomes
What are the features of the Protoctista kingdom?
- eukaryotes
- contain a nucleus
- nutrients from photosynthesis (autrophic feeders) and/or ingestion of other organisms (heterotrophic feeders)
- no cell wall
- some are immobile, others move using flagella, cilia, etc
- unicellular
What are the features of the Fungi kingdom?
- eukaryotes
- contain a nucleus
- cell wall made from chitin
- nutrients absorbed from decaying materials (saphrophic feeders) and stored as glycogen
- uni or multicellular
- don’t move
What are the features of the Plantae kingdom?
- eukaryotes
- contain a nucleus
- cell wall made from cellulose
- nutrients from photosynthesis (autrophic feeders) and stored as starch
- multicellular
- contain chlorophyll
What are the features of the Animalia kingdom?
- eukaryotes
- contain a nucleus
- nutrients from ingestion (heterotrophic feeders) and stored as glycogen
- no cell wall
- multicellular
- no chloroplasts
What are autotrophic feeders and which kingdoms are they?
organisms that synthesis the substances they need (ie. by photosynthesis)
-Plantae, some Prokaryotae, some Protoctista
What are heterotrophic feeders and which kingdoms are they?
organisms that feed on other organisms (ie. ingestion)
-Animalia, some Protoctista
What are saphrophic feeders and which kingdoms are they?
organisms that feed on decaying matter
-Fungi
What is the current classification system?
the three domain system
-3 domains + 6 kingdoms
What is phylogeny?
the evolutionary relationships between organisms
What do phylogenetic trees show?
evolutionary relationships
- oldest at bottom
- newest at top
What are the advantages of phylogeny?
- confirms classification grouping
- produces a continuous tree (classification only has discrete taxonomic groups)
What is evolution?
the process by which organisms change over millions of years as a result of natural selection
What happens in natural selection?
- organisms within a species show variation (because of differences in genes) -variation could occur by random mutations
- organisms that are best adapted to a selection pressure have an increased chance of survival
- if the organism survives, it can reproduce
- successful organisms pass on the allele for the advantageous characteristic to their offspring
- this is repeated over many generations so that the frequency of the advantageous allele increases
- over long periods of time/many generations, this can lead to a new species evolving
What is a selection pressure?
a factor that affects an organism’s changes of survival or reproductive success
eg. competition (mate/food), disease, predation
What evidence for evolution is there?
- fossils (palaenotology)
- molecular evidence
- comparative biochemistry (eg. order of DNA bases, rRNA, cytochrome C)
- comparative anatomy
What is variation?
differences in characteristics between organisms
What is interspecific variation?
variation between members of different species
What is intraspecific variation?
variation between organisms within a species
What are the causes of variation?
- organisms’ genetic material (=> genetic variation eg. eye colour, hair, etc.)
- environment where an organism lives (=> environmental variation eg. scars, piercings)
- both (eg. weight, skin colour, etc.)
What are the causes of genetic variation?
- alleles
- mutations
- meiosis (crossing over and independent assortment)
- sexual reproduction
- chance
What is discontinuous variation?
variation that can only result in certain values
- only caused by genetic factors (usually a single gene)
- normally represented in a bar chart or pie chart
eg. sex, blood group, shape of bacteria
What is continuous variation?
variation that can take any value in a range
- caused by environment and genes (a large number of genes)
- normally represented in frequency tables and then in a histogram or line graph (in a line graph this creates a normal distribution curve)
What is an adaption?
a characteristic that increases an organism’s chance of survival and reproduction in an environment
What are the three types of adaptions?
- anatomical (physical features)
- behavioural (the way they act -inherited of learnt)
- physiological (takes place inside an organism)
What are analogous structures?
structures different species both have with the same feature but from a different origin
- convergent evolution
eg. insect wing and bird wing
What are homologous structures?
structures different species both have with different functions but the same origin
- divergent evolution
eg. bat wing and human arm
