4.2.2 - Classification and Evolution Flashcards
5 kingdoms
Animalia Plant Fungi Protoctist Prokaryotae
Animal kingdom
Eukaryotic, multicellular
Heterotrophs
Fertilised eggs develop into a blastula
Fungi kingdom
Eukaryotic, uni/multicellular Multinucleate No chloroplasts/chlorophyll Strands of hyphae make up mycelium Often saprophytic
Protoctist kingdom
Eukaryotic, mostly single celled
Plant like and animal like, rejects of all other kingdoms
Variety of feeding mechanisms
How do prokaryotes respire
Using mesosomes
Heterotrophs
Nutrition is gained from the digestion of organic matter
Saprophytic
Feed on dead/ decaying matter
Classification
Grouping organisms on the basis of shared features
Modern classification reflects phylogeny
Taxonomy
Focuses physical similarities between diff. spp for ease of naming and identification
Phylogeny
Classification of organisms by evolutionary relationships so every group shares a common ancestor
Linnaean taxonomy
Carl Linnaeus formed a system that is the basis of our naming system
Taxons
Domain - Eukarya Kingdom - Animalia Phylum - Chordata Class - Mammalia Order - Primates Family - Hominidae Genus - Homo Species - Homosapiens
Carl Woese
Split Monera (prokaryotes) into Eubacteria, Archaebacteria Refined system to create 3 domains; Eukarya, Eubacteria and Archaebacteria
What do taxonomists do
Try to identify evolutionary relationships among organisms
Compare structures of organisms
Compare organisms geographic distribution and chemical makeup
Rule of parsimony
This assumes that the tree with the least number of evolutionary events is most likely to show the correct evolutionary relationship
Shared characteristics vs. shared derived characteristics
Shared characteristics look at convergent evolution but shared derived characteristics focus on features that are a result of shared ancestors (homologies)
Discontinuous variation is shown by
Qualitative traits determined by a single gene
Continuous variation is determined by
Large number of genes and have quantitative traits e.g. mass and length
Sources of genetic variation
Dominant alleles Recessive alleles Mutations Crossing over Independent assortment Gene interactions
Adaptive features
Inheritable traits that suit an organism to its niche
Acclimitisation
The ability to adapt during its lifecycle
Types of adaptations
Structural
Physiological
Behavioural
Darwin’s theory
Parents produce too many offspring
Competition causes better adapted offspring to survive
They will then reproduce and pass on those attractive features
Evidence for evolution
Fossil evidence
Molecular evidence
Forms of fossils
Imprints of ancient organisms
Remains
Fossil evidence
Scientists study fossils in minute detail in order to establish anatomical and morphological similarities which can then be used to reveal evolutionary relationships
Molecular evidence
More reliable than fossils
All living things have proteins and DNA. Sequencing the bases in DNA and amino acids in proteins show similarities and differences. More similarities, more closely related
Variation
Differences that arise between living organisms
Types of variation
Intraspecifc and interspecific
Continuous and discontinuous
Intraspecific variation
Variation between members of the same species, this causes evolution
Examples of differences caused by intraspecific variation
Observable features (colour) Biochemical differences (sequences of amino acids) Behavioural differences (type of food eaten)
Interspecific variation
Occurs between members of different species
Depends on how closely related one species is to the other
Anatomical adaptations
Those associated with structure e.g. predators have sharp teeth to help kill and chew prey
Physiological adaptations
Those associated with how the body systems functions e.g. yeast respire anaerobically when theres no O2 so they can produce ATP and continue growth
Behavioural adaptations
Those associated with feeding, nesting or mating e.g. robins choose nests close to the ground as to not compete with other bird species
Implications of evolution for humans
Pesticide resistance in insects
Drug resistance in micro-organisms
Why are estimated of total no. of species inaccurate
Species become extinct daily
Undiscovered species
Some species may be reclassified
Evidence used by taxonomists when classifying organisms
Behaviours
Fossil record
Embryology
Why can info gained from studying model organisms be applied to humans
Similar metabolism
Similar genes
Shared ancestry
Factors considered when choosing a model organism
Small
Short life cycle
Cheap to buy and keep
How does resistance arise and evolve in a population
SPONTANEOUS mutation in gene sequence e.g. base sub
Leads to resistance to the selective agent
beneficial mutation so directional selection
Through natural selection, those better adapted against the selective agent survive, reproduce and pass on that mutation
Increases frequency of allele in population
Use of fossils to estimate age
Deeper fossils are older than surface fossils
Why do scientists classify organisms
To identify species
To predict characteristics
To find evolutionary links
Plant kingdom
Multicellular
Nucleus and other membrane bound organelles
Autotrophs and store food as starch
Why have classification systems changed over time
Advances in science e.g, genome sequencing
Archaebacteria
Ancient bacteria - extremophiles
Advantages of phylogenetic classification
Phylogeny can be done w/out reference to Linnaean classification
Produces a continuous tress vs discrete taxonomical groups
Students t-test
Used to compare means of data values of 2 population
Spearman’s rank correlation coefficient
Used to consider relationship between two sets of continuous data
Analogous structure
Structures adapted to perform the same function but have a diff genetic origin
Convergent evolution
May have adapted to fill sim niches in diff environments but not related evolutionary
