B14: Variation & Evolution

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What is a species?
A group of organisms that can reproduce but their offspring will not be able to
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What are differences in characteristics called?
Variation
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How are differences between species caused?
The characteristics are inherited from their parents
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What do genes code for?
A protein
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Where are genes found?
On chromosomes which are in the nucleus
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Who do you inherit your genes from?
1/2 from Dad, 1/2 from Mum
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What are 2 people with identical genes called?
Clones of each other (identical twins)
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Each of your body cells has ... pairs of chromosomes
23 pairs
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Sex cells have ... chromosomes
23 chromosomes
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What did Darwin deduce from his observations?
Organisms are involved in a struggle for existence, only those most adapted to their environment survive
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What was Darwin's hypothesis called?
Evolution by Natural Selection
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What are the key steps in natural selection?
mutation of Gene -> advantage to survival -> breed -> pass on genes
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How does competition work in natural selection?
There is not enough food or space for all of them
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How does survival work in natural selection?
Some individuals have features which help them survive
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How does reproduction work in natural selection?
They are more likely to have offspring, more of next generation have the usual feature
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How does variation work in natural selection?
All living things in a species are not the same
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What is selective breeding?
When humans deliberately choose plants and animals for desired characteristics
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What are the risks of selective breeding?
Reduces variation in the alleles, Inbreeding (breeding with close relatives, some breeds of dogs prone to diseases)
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Examples of dogs prone to diseases (as a result of selective breeding)?
Boxer dogs (epilepsy), King Charles Spaniels (brains too big/heart defects), Pugs (breathing difficulties)
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What is genetic engineering?
When we change the genes of an organism to get what we desire
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Steps of genetic engineering?
Enzymes 'cut out' genes -> insert vector (plasmid/virus) -> vector used to insert gene into cells -> genes transferred to cells, new desired characteristics
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List some advantages of GM crops?
Improves growth rates of plants & animals, Improves food value of crops, possible cues for genetic diseases, produce plants that make their own pesticide chemicals
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List some disadvantages of GM crops?
Genes from GM plants might spread to environment, People may want to manipulate the genes of their own children, Insects may become pesticide-resistant if they eat constant diet of pesticide-forming plants, Effect on human health of GM unknown
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Other cards in this set

Card 2

Front

What are differences in characteristics called?

Back

Variation

Card 3

Front

How are differences between species caused?

Back

Preview of the front of card 3

Card 4

Front

What do genes code for?

Back

Preview of the front of card 4

Card 5

Front

Where are genes found?

Back

Preview of the front of card 5
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