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22 Cards in this Set
- Front
- Back
Heredity |
The passing on of physical or mental characteristics genetically from one generation to another |
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State 3 reasons plant and animal breeders manipulate hereditary |
Improve plant crops Improve animal stock Improve sustainable production |
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State 3 reasons a plant field trial would be carried out |
Compare performances of 2 different cultivars under the same environmental conditions. Find out the effect of different environmental conditions on a new cultivar of a crop plant. Evaluate GM crops |
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Describe the importance of factors during a field trial |
Treatments selected must ensure a fair comparison. The number of replicates must be enough to account for variability within the sample. Randomisation of treatments eliminates bias when measuring treatment effects. |
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Outbreeding |
When 2 unrelated individuals cross-breed via the fusion of gametes. |
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State the two organisms that are naturally outbreeding |
Animals and cross-pollinating plants |
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Describe inbreeding in terms of loss of heterozygosity |
Inbreeding results in a loss of genetic variation and can eliminate heterozygosity meaning more homozygous individuals. |
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Inbreeding depression |
When chances of becoming double recessive for an undesirable trait increase and inbreeding depression can arise |
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How is inbreeding depression avoided in self pollinating plants |
Deleterious genes will have been eliminated through natural selection |
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How is inbreeding depression avoided in outbreeding species |
One desired trait is selected for but all other traits remain diverse |
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Crossbreeding |
Creating a hybrid organism through the sexual reproduction of 2 parent organisms |
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Describe why crossbreeding can be beneficial |
It introduces new alleles into the next generation. It may provide an F1 population with improved characteristics. |
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Backcross |
A cross where an individual is crossed with one of its parents or with an individual possessing exactly the same genotype as one of its parents. |
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State two ways a new breed can be maintained |
By backcrossing and maintaining the parent generation to breed. |
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Describe F1 hybrids |
Uniformly heterozygous, this means they have the same genotype. Display increased vigour, yield and fertility. The poorer recessive alleles are masked by superior dominant ones. |
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Explain why the F2 generation is unsuitable as a crop |
They show increased variation and diversity |
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State one benefit of the F2 generation |
They can provide a source of new varieties. |
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Testcross |
Used to identify the unknown genotype of an organism with the dominant phenotype |
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How does a testcross work |
The individual with the unknown genotype is crossed with a homozygous recessive individual |
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State why genome sequencing is important for breeding |
It allows organisms with an allele for a desirable characteristic to be identified |
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Genetic transformation |
Transferring DNA from one species to another. This is how GM crops are produced |
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State why genetic transformation is important for breeding |
Allows for desirable characteristics to be added to an organisms DNA |