13006285
Description
Flashcards by Mrs Z Rourke, updated more than 1 year ago
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Created by Mrs Z Rourke
over 6 years ago
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| Question | Answer |
| 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] |
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What type of variation is shown in the graph?
Image:
Discon (binary/octet-stream)
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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 |
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Explain how bacteria are becoming resistant to antibiotics
Image:
Mrsa (binary/octet-stream)
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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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