CB4 - Natural Selection and Genetic Modification

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  • CB4 - Natural Selection and Genetic Modification
    • CB4c - Classification
      • organisms are classified into smaller and smaller groups (based on their characteristics)
        • as the characteristics of the organisms became more and more similar, the groups became smaller and smaller
      • genus - loxodonta
      • species - africana
      • the five-kingdom system of classification
        • 1) animals
          • multicellular (with cells arranged as tissues and organs)
          • cells have nuclei
          • no cell walls
        • 2) plants
          • multicellular (with cells arranged as tissues and organs)
          • have chloroplasts for photosynthesis
          • cells have nuclei
          • cellulose cell walls
        • 3) fungi
          • multicellular (apart from yeasts)
          • live in or on the dead matter on which they feed
          • cells have nuclei
          • cell walls contain chitin (not cellulose)
        • 4) protists
          • mostly unicellular (a few are multicellular)
          • cells have nuclei
          • some have cell walls (made of different substances but not chitin)
        • 5) prokaryotes
          • unicellular
          • cells do not have nuclei
          • flexible cell walls
    • CB4d - Breeds and varieties
    • CB4a - Evidence for human evolution
      • evolution - a change in one or more characteristics of a population over a long period of time
      • binomial system - the system of naming organisms using 2 Latin words
        • binomial species names
          • Indian peafowl - Pavo cristatus
          • modern humans - Homo sapiens
      • scientists use fossils to find out about human evolution
        • they work out how old the fossils are then put them in age order
      • stone tools - any tool made partially or entirely from stone
        • stone tools are dated by assuming they are about the same age as that layer of rock
      • Stone tools made by human-like species developed over time as the more recent stone tools found were more sophisticated
      • fossil evidence for human-like species
        • 4.4 million years ago - The bones that make up Ardi’s feet suggest that humans and chimpanzees evolved separately
        • 3.2 million years ago - Lucy’s bones suggest that she walked in an upright position, like a human, but possessed a relatively small ape-like skull.
        • 1.6 million years ago - microscopic study of the teeth indicates that it grew up at a growth rate similar to that of a great ape. Fossil evidence shows this species cared for old and weak individuals
      • Ardi is a female human-like fossilised skeleton that dates from 4.4 million years ago
      • Lucy is also a female human-like fossilised skeleton, and dates from 3.2 million years ago
    • CB4b - Darwin’s theory
      • genetic variation (aka inherited variation) - differences between organisms caused by differences in the alleles they inherit from their parents, or differences in genes caused by mutation
      • natural selection - a process in which certain organisms are more likely to survive and reproduce than other members of the same species because they possess certain genetic variation
        • 'survival of the fittest'
      • natural selection allows some members of a species survive better than others when conditions change
        • those members of the species gained features which helped them to survive
      • natural selection can lead to the evolution of a new species
        • 2 animals can evolve from the same animal (they share a common ancestor)
          • conditions changed for the ancestor
            • due to genetic variation, some animals will adapt better to the difference
              • the ones that adapted were more likely to survive that the others that didn't/couldn't
                • more of these individuals survived and bred forming a new species over time
      • the development of resistance in organisms supports Darwin’s theory
        • due to genetic variation, there will always be certain individuals in a species, resistant to different things
          • if there is a product that can kill a species, not all individuals will die because some will be resistant to the product
            • this resistance will lead to the resistant individuals surviving and breeding with other resistant individuals leading to more resistant individuals
    • CB4e - Genes in agriculture and medicine
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Please, can you do CB4e soon?? These are all bare helpful btw like thanks sm

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