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Description
Flashcards by Lily Pritchard, updated more than 1 year ago
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Created by Lily Pritchard
about 8 years ago
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| Question | Answer |
| what is selective breeding? | when humans artificially select plants or animals that are going to breed and have their genes remain in the population, according to what we want from them |
| organisms are selectively bred to develop the best features which are things like? (3) | maximum yield of meat, milk, grain etc... good health and disease resistance other quantities like temperament, speed, attractiveness etc... |
| what is the basic process involved in selective breeding? | 1. from your existing stock select the ones which have the best characteristics 2. breed them with each other 3. select the best of the offspring, and breed them together 4. continue this process over several generations, and the desirable trait gets stronger and stronger |
| what is the main problem with selective breeding, how does this happen? | it reduces the gene pool - the number of alleles (forms of a gene) in a population this is because the farmer keeps breeding from the 'best' animals or plants - which are all closely related >>> this is known as interbreeding |
| how can interbreeding cause health problems? | because there is more chance of the organism developing harmful genetic disorders when the gene pool is limited, because lots of genetic conditions are recessive, breeding from closely related organisms all the time means that recessive alleles are more likely to build up in the population (as organisms are likely to share the same alleles) |
| why there a serious problem if a new disease appears? | because there is not much variation in the population > as the stock are all closely related to each other, so if one of them is going to be killed by a new disease, the others are also likely to do so |
| what is the flow chart for selective breeding? | selective breeding > reduction in the number of different alleles (forms of a gene) >> less chance of any resistant alleles being present in the population |
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