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Classification - Coggle Diagram

- - - - Alleles-inheriting a different allele of a gene.
        Mutations-changes in the DNA sequence will change the protein coded for; if this occurs in a body (somatic) cell, only the individual will be affected; if it is in a gamete, the mutation could be passed on.
        Meiosis-independent assortment and crossing over
        Sexual reproduction-inheritance of alleles from both parents; so the offspring are different from the parents.
        Chance-random fusion of gametes
    - - Variation due to changes in the environment. Plants are more affected than animals as they are immobile. eg Effect of light on plant growth. Soil type
    - - Most variation is caused by genetic and environmental factors (‘nature or nurture’). Studies often focus on identical twins; characteristics in which they show most variation must be influenced most greatly by the environment and not by genes. eg if you inherit tall genes, but have a poor diet; inheritance of melanin pigmentation and exposure to sunlight.
- - - - -Organisms produce more offspring than survive.
      - -There is variation in the characteristics of members of the same species.
      - -Some characteristics can be passed on from one generation to the next.
      - -Individuals that are best adapted to their environment are more likely to survive.
    - - -Separately made similar observations to Darwin eg advantageous characteristics to deter predators by beetles and butterflies.
  - - - Variation must exist in the population (due to mutations)
      - Competition must occur so that one form is better adapted than the other. This is called a selection pressure.
      - Selection pressure causes the weaker forms to die and their population starts to decrease.
      - Selection pressure causes the stronger form to survive to an age that they can reproduce.
      - When the stronger form reproduce their allele are passed onto the next generation
      - The next generation has a larger population of the stronger form
  - - - Advantages of fossil evidence: Radioisotopes can be used to date fossils Changes can be tracked over time Chronological order apparent in rock strata
      - Disadvantages of fossil evidence: Decomposition of many organisms Small chance of fossilisation Destroyed by geographic activity