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Life on
- Characteristics 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 characteristics of populations through successive generations.
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Natural selection
It's very important to memorize what natural selection is in I/GCSE Biology!
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
- Characteristics 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
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Characteristics best adapted ➡️ increase in population in next generation = natural selection
- Natural selection ➡️ a natural process whereby the organisms with genetic characteristics best suited to their environment survive to reproduce and pass on their genes to the next generation
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How evolution occurs
- Evolution because of environment change
- Different characteristics best suited to new conditions
- Best suited ➡️ survive + breed
- Characteristics changed so much, organisms become new species
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Genes and mutation in evolution
Variation in inherited characteristics between individuals caused by having different forms of genes
- Different forms caused by mutations
Mutation ➡️ a change in a gene that may result in different characteristics
- Mutations no effect on survival – some ➡️ fatal/disadvantageous e.g. miscarriage but some ➡️ advantageous
- For example:
- 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
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And we're done with this topic! Well Done!
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Drafted by Alyssa (Biology)
References:
- "Darwin's Contribution-The Theory of Evolution & Natural Selection", https://cdn1.byjus.com/wp-content/uploads/2015/12/Evolution.jpg
- "EVOLUTION CHARLES DARWIN IN LATER YEARS 1 HISTORY", https://slidetodoc.com/presentation_image_h/2d9392e857d025f3fb715276296425ed/image-34.jpg
- "Natural Selection", https://ib.bioninja.com.au/_Media/natural-selection_med.jpeg
- "Evolution", https://fayllar.org/evolution-are-the-changes-in-the-gene-pool-of-a-population-ove/img12.jpg
- "Directed evolution", https://dnadots.minipcr.com/wp-content/uploads/2018/10/directed-evolution.png