1. Choose parents with the desired feature and breed them together
2. Chose off spring for the desired features
3. Then cross-breed the offspring, showing the features with each other
4. Continue over many generations of crossing and selecting
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DISADVANTAGES OF USING SEXUAL REPRODUCTION IN PLANTS (3)
1. Requires two gametes
2. Time-consuming
3. there is a variation in off spring
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MEIOSIS (4)
1.nuclear division
2. the number of chromosomes is halved
3.from diploid to haploid
4. Results in genetically different cells
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WHY COAT COLOUR IS AN EXAMPLE OF DISCONTINUOUS VARIATION (4)
1. It is controlled by the genes
2. not affected by the environment
3. there are distinct phenotypes
4.no continuous range of colours
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LITTLE GENETIC VARIATION (3)
1. Gametes are from the same parent
2. only new source of variation is mutation
3. variation is produced through miosis
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DNA IS LOCATED(2)
1. nucleus
2. chromosomes
3.mitochondria
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FEED ON DECAYING MATERIAL. WHY IMPORTANT ROLE IN ECOSYSTEM? (3)
1.remove organic waste materials
2.recycles nutrients
3.releases carbon as co2
4. Co2 is used for photosynthesis
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WHY MEIOSIS
1. Chromosome number is halved
2.prevents doubling of chromosome number, with each generation
3.haploid cells
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WHY MITOSIS
1. Growth is taking place
2.producing (genetically) identical cells
3.more diploid cells
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MEANING OF DOMINANT ALLELE
The allele that is expressed
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CAUSE OF DOWN SYNDROME
An extra chromosome, DNA mutation
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DISCONTINUOUS VS CONTINUOUS VARIATION (4)
discontinuous variation –
1. Influenced by genes alone
2.no effect of the environment
3.is discrete
4.limited number of phenotypes
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PROBLEMS OCCUR WITH SICKED CELL ANAEMIA (4)
1.(red blood cells) get stuck in capillaries
2.reduce, supply of, oxygen to cells
3.increased chance of, blood clotting
4.reduce, removal of, carbon dioxide in cells
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TERM : DEVELOPMENT (2)
1. increase in, complexity
2.different types of cells
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WHY DISTRIBUTION OF SCA AND MALARIA ARE SIMILAR (5)
1.malaria, is severe disease
2.people with sickle cell anaemia HbS are resistant to malaria
3.HbN HbN homozygous dominant, are susceptible to malaria
4. HbN HbN more likely to die (of malaria) before have children (to pass
on genes);
5.HbN HbS ,sickle cel
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WHY SCA IS RARE AMONG THOSE PLACES
1.malaria not very serious
2.people have other genetic protection from malaria
3.malaria has only recently spread to these areas
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WHY MEIOSIS IS SUITABLE FOR GAMETE PRODUCTION (2)
1.produces genetically different cells- produces variations
2.has half the number of chromosomes from diploid to haploid
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Other cards in this set
Card 2
Front
GENE MUTATION
Back
A change in the base sequence of the DNA
Card 3
Front
SELECTIVELY BREED PLANT (4)
Back
Card 4
Front
DISADVANTAGES OF USING SEXUAL REPRODUCTION IN PLANTS (3)
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