Classification and evolution Flashcards
Need for a classification system
- To identify species
- To find evolutionary links
- To predict characteristics
- Scientists around the world can share their research
Linnean classification
Hierarchy based on taxonomic groups:
domain, kingdom, phylum, class, order, family, genus, species
Mnemonic of taxonomic groups
King Philip Came Over From Great Spain
Species definition
A species is the smallest taxonomic group that consists of organisms that are able to reproduce to produce fertile offspring.
Handwritten version of a scientific name
underlined + genus starts with uppercase
The five kingdoms
Prokaryotes (bacteria) Protoctista Fungi Plantae Animalia
Prokaryotes features
eg: E. coli
Type of organism: unicellular
Genetic material: ring/circular naked DNA
Feeding mechanism: not visible, absorbed through cell wall or produced by photosynthesis
Protoctista features
eg: Paramecium and Amoeba
Type of organism: unicellular
Organelles: nucleus, membrane-bound organelles, chloroplasts
Movement: sessile/ by cilia, flagella, amoeboid mechanism
Feeding mechanism: autotrophic (photosynthesis), heterotrophic (ingestion of other organisms), or parasitic (both)
Fungi features
eg: mushrooms, moulds, yeast
Type of organism: unicellular or multicellular
Organelles: nucleus, membrane-bound organelles, cell wall made of chitin
No movement
Body/mycelium made of shreds/hyphae
Feeding mechanism: saprophytic (absorption of nutrients) and parasitic - food stored as glycogen
Plantae features
eg: flowering plants, trees, grass
Type of organism: multicellular
Organelles: nucleus, membrane-bound organelles (eg chloroplasts with chlorophyll), cell wall made of cellulose
Movement: most do not move, however gametes of plants move with the aid of cilia or flagella.
Feeding mechanism: autotrophic (photosynthesis) - food stored as starch
Animalia features
eg: humans, reptiles, mammals, sponges etc
Type of organism: multicellular
Organelles: nucleus, membrane-bound organelles (no cell wall)
Movement: cilia, flagella, contractile proteins, muscular organs
Feedings mechanism: heterotrophic (ingestion) - food stored as glycogen
Domains
Eukarya, Archae, Bacteria
Discovered by Carl Woese
Classification based on differences in sequences of nucleotides in cells’ rRNA, cells’ membrane lipid structure, and sensitivity to antibiotics.
Eukarya characteristics
80s ribosomes
RNA polymerase contains 12 proteins
Archae characteristics
70s ribosomes
RNA polymerase contains 8-10 proteins
Bacteria characteristics
70s ribosomes
RNA polymerase contains 5 proteins
Woese’s 6 kingdoms
Eubacteria Archae-bacteria Protoctista Fungi Plantae Animalia
Phylogeny
Evolutionary relationships between organisms
Phylogenetics
Study of evolutionary history of groups of organisms
Advantages of phylogeny over Linnean classification
- -> Phylogeny produces a continuous tree, while classification requires discrete taxonomic groups.
- -> Linnean classification has a hierarchal nature which can be misleading as it can suggest that different groups in the same rank are equivalent (eg cats and orchids)
Evidence for evolution
- Paleontology (study of fossils and fossil records)
- Comparative anatomy
- Comparative biochemistry
Homologous structure
Structures that appear superficially different, but have the same underlying structure. This provides evidence for divergent evolution (result of migration or loss of habitat)
Molecules studied for comparative biochemistry
Cytochrome c (involved in respiration) and ribosomal RNA
Types of variation (based on what it affects)
Interspecific (between 2 or more different species)
Intraspecific (between organisms of the same species)
Causes of variation
- Alleles
- Mutations (either in somatic cells - only individual is affected, or in gametes - mutation is inherited)
- Meiosis (independent assortment and crossing over)
- Random fertilisation due to chance
Types of variation (based on type of data collected)
Continuous (height, weight) - polygenic and environmental
Discontinuos (shape of microorganisms, human blood groups) - monogenic
Student’s t test
Used to compare means of data values of 2 populations
Spearman’s rank correlation coefficient
Analysing the relationship between 2 sets of data
Types of adaptations
Anatomical
Behavioural
Physiological
Anatomical adaptations
body covering
camouflage
teeth
mimicry
Behavioural adaptations
courtship survival behaviours (eg playing dead) seasonal behaviours (eg migration, hibernation)
Types of behavioural characteristics
Innate (inherited through genes)
Learned (learnt from experience)
Physiological characteristics
poison production
antibiotic production
water retention
Analogous structures
Unrelated species that have different genetic origins, but have adapted to perform the same function. Evidence for convergent evolution (due to adapting to similar environments/selection pressures)
Selection pressure
Factors that affect an organism’s chances of survival or reproductive success
