4.2.2 - Classification and Evolution Flashcards by Cullain Escott

5 kingdoms

Animalia 
Plant 
Fungi 
Protoctist
Prokaryotae

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Animal kingdom

Eukaryotic, multicellular
Heterotrophs
Fertilised eggs develop into a blastula

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Plant kingdom

Eukaryotic, multicellular

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Fungi kingdom

Eukaryotic, multicellular
Multinucleate
Strands of hyphae make up mycelium
Often saprophytic

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Protoctist kingdom

Eukaryotic, mostly single celled
Plant like and animal like, rejects of all other kingdoms
Variety of feeding mechanisms

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How do prokaryotes respire

Using mesosomes

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Heterotrophs

Nutrition is gained from the digestion of organic matter

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Saprophytic

Feed on dead/ decaying matter

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Classification

Grouping organisms on the basis of shared features

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Taxonomy

Focuses physical similarities between diff. spp for ease of naming and identification

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Phylogeny

Classification of organisms by evolutionary relationships so every group shares a common ancestor

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Linnaean taxonomy

Carl Linnaeus formed a system that is the basis of our naming system

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Taxons

Domain  - Eukarya 
Kingdom - Animalia 
Phylum - Chordata 
Class - Mammalia
Order - Primates 
Family - Hominidae
Genus - Homo 
Species - Homosapiens

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Carl Woese

Split Monera (prokaryotes) into Eubacteria, Archaebacteria
Refined system to create 3 domains; Eukarya, Eubacteria and Archaebacteria

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What do taxonomists do

Try to identify evolutionary relationships among organisms
Compare structures of organisms
Compare organisms geographic distribution and chemical makeup

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Rule of parsimony

This assumes that the tree with the least number of evolutionary events is most likely to show the correct evolutionary relationship

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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)

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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

Where did Alfred Russell and Wallace collate evidence

Southeast Asia

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 sound 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