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Title: GCSE Biology 2.4 - Variation and Evolution
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A.) This is one of eight topics in the unit.

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g
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sometimes too slow for organisms to adapt to new environmental conditions and so
organisms may become extinct
proposed by Alfred Russell Wallace and Charles Darwin, who were both working on the
ideas of evolution and natural selection at around the same time

Evolution


ongoing, as illustrated by antibiotic resistance in bacteria, pesticide resistance and warfarin
resistance in rats

The human genome


important, because it uses information from DNA to develop new ways to treat, cure or even
prevent disease

Mutations





changes in existing genes, resulting in new genes
occur at random
sometimes beneficial or harmful
more likely after exposure to ionising radiation

Cystic fibrosis





an inherited disease
causes the production of thick mucus that blocks the bronchioles
arises as a mutation
can be inherited as a recessive allele

Gene therapy in cystic fibrosis sufferers






has potential to treat cystic fibrosis
not straightforward, as the introduction of genes is not sufficient, as they should be able to
work within the body
has difficulties targeting the appropriate cells
not a cure for the underlying condition
involves introducing the genes into the lung tissue via an inhaler

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Title: GCSE Biology 2.4 - Variation and Evolution
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A.) This is one of eight topics in the unit.