Year 11 - Topic 4: Variation and evolution

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GCSE Biology FlashCards sobre Year 11 - Topic 4: Variation and evolution, criado por Mrs Z Rourke em 26-03-2018.
Mrs Z Rourke
FlashCards por Mrs Z Rourke, atualizado more than 1 year ago
Mrs Z Rourke
Criado por Mrs Z Rourke mais de 6 anos atrás
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Resumo de Recurso

Questão Responda
What type of variation is shown in the graph? Continuous variation
Describe the graph opposite [3] The graph shows continuous variation [1] There is a bell shaped curve- normal distribution curve [1] Any relevant data i.e. range of heights [1]
What type of variation is shown in the graph? Discontinuous variation
What causes continuous variation? Genes and environment
Name some examples of continuous variation. Height Weight Hand span
What causes discontinuous variation? Genes
Name some example of discontinuous variation Gender Eye colour Blood group
What is the difference between sexual and asexual reproduction? Sexual reproduction - leads to offspring being genetically different from parents. This gives rise to variation Asexual reproduction - genetically identical offspring are produced i.e. clones
How are new genes produced? Mutations (changes in genes)
Do mutations always have an effect? Not always - some mutations can be harmful, beneficial or have no effect at all
How can you increase the chance of mutation? Mutation rates can be increased by ionising radiation
What are the effects of cystic fibrosis? Cystic fibrosis is an inherited disease that causes the production of thick mucus that blocks the bronchioles
How is cystic fibrosis inherited? The child must inherit a recessive allele from each of the parents as cystic fibrosis is a recessive disease
How can gene therapy be used to treat cystic fibrosis? Gene therapy has potential to treat this condition, but is not straightforward as the introduction of genes must be able to work within the body. There are also difficulties in targeting the appropriate cells and it is not a cure for the underlying condition. The genes can be introduced into the lung tissue via an inhaler.
What is evolution? A gradual change over time
What are the stages of natural selection? 1. Over-production - all organisms produce more offspring than will survive 2. Variation - all organisms within a species will show variation (sometimes caused by mutation) 3. Competition - those organisms that are better adapted will survive 4. Reproduction - survivors will breed and pass on their advantageous genes to their offspring
Who proposed natural selection? Alfred Russell Wallace and Charles Darwin
Why do some species become extinct? The process of natural selection is too slow for organisms to adapt to their new environment and so, become extinct
Explain how bacteria are becoming resistant to antibiotics 1. Variation – some strains of bacteria are resistant and some aren’t. 2. Competition – The non-resistant bacteria are killed by the penicillin. 3. Survival of the fittest – the resistant bacteria survive. 4. Passing on of genes – the resistant bacteria reproduce and pass on their adaptations to their offspring.
Why is it important to increase our understanding of the human genome? It could be used to develop new ways to treat, cure or even prevent disease.

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