Biology Paper 1 - Topic 4: Natural Selection + GM

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  • Created by: JS13
  • Created on: 28-11-21 11:54
What is selective breeding?
Humans select organisms with desirable characteristics and they are then bred together. The offspring will have that characteristic. The offspring are then bred together to produce more offspring with similar phenotypes
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How is it carried out?
1) Identify the characteristic desired
2) Select parents which show the trait and breed them together
3) Select the offspring who display that characteristic
4) Repeat the process so there are many offspring with the desired characteristic
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What makes it good? (What are some traits that are desirable?)
Creates organisms with desired traits
Some traits include:
Crops with higher yield
Cows producing more milk
Plants that produce larger fruit
Domesticated animals
Sports that involve animals e.g. horse racing
Medical research
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What are the drawbacks?
Reduction in gene pool may lead to a species being unable to survive in a sudden environmental change
Inbreeding can lead to genetic disorders
We can unknowingly select harmful alleles
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What are two ways in which plants can be cloned?
Using plant cuttings
Tissue culture
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What is tissue culture? (How is it carried out?)
Growing living tissue in a medium.
1) Plants that show desired traits have tissue from their meristem cut
2) This is then grown in a petri dish containing a growth medium (nutrients and growth hormones) using aseptic techniques
3) When large enough it is
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Why is it good?
Fast and simple process
Doesn't take up a lot of space
Useful in preservation of endangered plant species
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What are the drawbacks?
Reduction in gene pool
May increase the number of harmful alleles
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What is genetic engineering?
1) Restriction enzymes are used to cut DNA where the desired gene is found and creates sticky ends
2) The restriction enzymes are also used to cut vector DNA to create complementary sticky ends
3) Ligase enzymes join them to form recombinant DNA which is
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Benefits
Useful in medicine e.g. insulin-producing bacteria,
GM crops like golden rice can provide vitamin-A
Increase crop yield (as they can develop resistance to certain pathogens)
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Negative
We don't know the long term effects of consuming GM crops
GM crops can reduce biodiversity and impacts food chains
GM seeds are expensive
GM animals can struggle living e.g. cows develop so much muscle that they can no longer stand
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What is intensive farming?
Using pesticides and fertilisers.
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Benefits
Increases crop yields
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Drawbacks
Excessive use of fertilisers can lead to eutrophication of nearby bodies of water, harming aquatic life
Herbicides and pesticides reduce biodiversity and affect food chains
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Biological Control
Introducing a predator into an ecosystem to control a pest or pathogen
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Benefits
The pathogen or pest being controlled lasts over a long period of time
Effects on wildlife less severe
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Drawbacks
The control organism may become a pest itself
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Other cards in this set

Card 2

Front

How is it carried out?

Back

1) Identify the characteristic desired
2) Select parents which show the trait and breed them together
3) Select the offspring who display that characteristic
4) Repeat the process so there are many offspring with the desired characteristic

Card 3

Front

What makes it good? (What are some traits that are desirable?)

Back

Preview of the front of card 3

Card 4

Front

What are the drawbacks?

Back

Preview of the front of card 4

Card 5

Front

What are two ways in which plants can be cloned?

Back

Preview of the front of card 5
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