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
Key Terms
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...
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
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| Term | Definition |
|---|---|
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 |