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Do you guys still remember the evolution by natural selection in I/GCSE Biology?
Life
- CH selected from breeding species e.g. dogs, change over time
- Theory of evolution = the theory that explains how all living things today have been produced by the accumulation of inherited changes in the CH of populations through successive generations.
Natural selection
- Darwin observed from organisms
- Organisms produce many more offspring than survive to adulthood
- There is variation between the individuals of a species and in the offspring they produce
- CH are passed from one generation to the next
- The individuals that are best adapted to the environment are the ones that survive and produce offspring in the next generation
- Refer to I/GCSE Biology, CH best adapted = increase in population in next generation = natural selection
- Natural selection = a natural process whereby the organisms with genetic CH best suited to their environment survive to reproduce and pass on their genes to the next generation
How evolution occurs
- Evolution because of environment change
- Different CH best suited to new conditions
- Best suited = survive + breed
- CH changed so much, organisms become new species
Genes and mutation in evolution
- Variation in inherited CH between individuals caused by having different forms of genes
- When it comes to I/GCSE Biology, Different forms caused by mutations
- Mutation = a change in a gene that may result in different CH
- Mutations no effect on survival – some = fatal/disadvantageous e.g. miscarriage but some = advantageous
- Africans = dark skin, protects from sunlight (homo sapiens evolved from Africa)
- Northern areas = pale skin (genetic mutation)– improves health in people in that area
- Rate of change in species = not constant – depends on how quick environment changes + difficulty rate to survive in new conditions
- If conditions changed so much then no variation will survive and species become extinct
That's all~
