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Section G: Natural and Artificial selection (evolution (shown in evolution…
Section G: Natural and Artificial selection
Variation
some characteristics caused by the
environment
e.g. the language we use, scars
other characteristics are inherited from parents e.g. eye colour, nose shape. They are
genetic
some characteristics e.g. intelligence & body mass are a result of
both
Mutation
mutations lead to variation
albino hedgehog - gene controls production of melanin. In albinos, the gene mutates so it no longer codes for the production of melanin
variation is necessary for evolution to occur
mutations = change in a gene
mutations occur naturally, rarely & at random
new genes result from changes in existing genes
3.31
sometimes mutations are harmful (disadvantageous), but they can also be neutral or beneficial
evolution
evolution is the gradual change in features or characteristics of a species over time
evolution - formation of species over time
Darwin - origin of species
shown in fossils
Darwin went to Galapagos Islands
evolution occurs from mutations & natural selection - based on data & 'wisdom'
survival of the fittest - competition for limited resources
moths - light & dark
variation
selection
survival
inheritance
shown in evolution of a horse
each horse adapted to its environment by natural selection
from marshy areas to dry areas
changed over millions of years
longer legs & lost toes to be faster
3.33 - triple science
Bacterial resistance to antibiotics
then the bacteria is able to survive
bacteria without gene would die or cannot reproduce with antibiotics present
some mutations protect the bacteria
once they have developed a resistance they then pass it on through the genes
random changes or mutations occur in the genes or individual bacteria cells
over many generations, most will become resistant to antibiotics
selective breeding
selective breeding = artificial insemination
problems - traits chosen to benefit humans not animals
desired characteristics
physical issues can occur e.g. inflammation in cow's udder
wheat - dwarf wheat + tall wheat breeding
dogs bred for hunting & farming - selectively bred for 15000 years
bred together
repeated over generations until achieved
wanted characteristics from 2 organisms to create desired features
only offspring with desired characteristics bred
