BRAINCAKE

Classification and Evolution

OCR AS-level BiologyTopic 10 of 1236 lessons

Revision notes for Classification and Evolution in OCR Biology A (H020). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.

  1. ClassificationThe sorting of living organisms into groups is known as classification.
  2. Classifying OrganismsThe three main reasons scientists classify organisms is to be able to identify them, predict their characteristics and identify evolutionary links.
  3. Naming OrganismsInstead of giving organisms common names that reflect their physical appearance, behaviour or habitat, the binomial system is used.
  4. The Five KingdomsThe domain Eukarya is divided into four kingdoms: Protoctists, Fungi, Plantae and Animalia.
  5. ProkaryotaeProkaryotes(bacteria) are unicellular organisms with no nucleus or membrane-bound organelles.
  6. ProtoctistaProtoctists are mainly unicellular eukaryotic organisms with a membrane-bound nucleus and membrane-bound organelles.
  7. FungiFungi can be unicellular or multicellular organisms.
  8. PlantaeThe plant kingdom consists of multicellular organisms that make food by photosynthesis.
  9. AnimaliaAnimals are the largest kingdom.
  10. ClassificationClassification of organisms changes as more knowledge emerges.
  11. The Three Domain SystemA domain is the highest taxonomic rank.
  12. Archaebacteria and EubacteriaArchaebacteria are ancient bacteria that live in extreme conditions (extremophiles) such as thermal vents, anaerobic conditions and highly acidic…
  13. PhylogenyThe hierarchical classification system is based on supposed evolutionary lines of descent.
  14. Advantages of Phylogenetic ClassificationPhylogenetic classification has two main advantages over Linnaean classification.
  15. Theory of EvolutionEvolution is a theory that describes the way in which organisms change over time as a result of natural selection.
  16. Evidence for EvolutionEvidence of common descent of living organisms has been discovered by scientists researching in a variety of disciplines over many decades, which…
  17. PalaeontologyFossils are formed when plants and animal remains are preserved in rocks due to the organisms dying and layers of sediment being deposited on top of…
  18. Comparative AnatomyPhylogenetic classification is based on evolutionary relationships between organisms and their ancestors and homologous characteristics which have…
  19. Comparative BiochemistryScientists can study the similarities and differences in the DNA and proteins of different species.
  20. Types of VariationVariation occurs as a result of random mutations and is important for the process of natural selection.
  21. Genetic Causes of Variation - MutationMutations are changes to the DNA base sequence that result in changes to the amino-acid sequence of proteins.
  22. Genetic Causes of Variation - Meiosis and ChanceDuring meiosis 1 crossing over leads to each chromatid being different.
  23. Environmental Causes of VariationMany characteristics are caused by a combination of both the environment and genes.
  24. Discontinuous VariationVariation can be continuous or discontinuous.
  25. Continuous VariationVariation can be continuous or discontinuous.
  26. Normal DistributionA normal distribution curve is a continuous line graph that is symmetrical about the mean.
  27. Standard DeviationStandard deviation measures how spread out data is and is a measure of the amount of variation in a data set.
  28. Student T-testThe student t-test is used to compare the means of data values of two populations.
  29. Spearman's Rank Correlation CoefficientSpearman's rank correlation coefficient shows whether or not two sets of data are related.
  30. AdaptationsAdaptation is the evolutionary process whereby an organism becomes better able to live in its habitat.
  31. Anatomical AdaptationsThe body of animals is covered with hairs, scales, feathers, shells or spines.
  32. Courtship BehaviourIndividuals can recognise members of their own species by behaviour.
  33. Physiological AdaptationsPhysiological processes take place inside the body.
  34. Convergent EvolutionConvergent evolution occurs when unrelated species begin to share similar traits.
  35. Natural SelectionMutation leads to the formation of new alleles.
  36. Modern Examples of Natural SelectionAntibiotic resistant bacteria MRSA (Methicillin resistant staphylococcus aureus) has developed resistance to many antibiotics.

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