Term
| How does reproduction contribute to variation within a species? |
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Definition
| gemetes from two parents combine |
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Term
| Name the two types of variation. |
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Definition
| discrete variation and continous variation |
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Term
| Which type of variation is caused by single genes (single gene inheritance) |
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Definition
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Term
| Which type of in heritance is caused by mny genes (polygenc inheritance) |
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Definition
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Term
| Describe discrete variation. |
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Definition
| measurements fall into distinct groups. |
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Term
| Describe continuous variation. |
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Definition
| there is a range of values between a minimum and a maximum |
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Term
| Give examples of discrete variation. |
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Definition
| tongue rolling / flower colour / left or right handed / pea shape 9round / wrinkled) / blood group |
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Term
| Give examples of continuous variation. |
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Definition
| height of limpet shell / weight of person / length of leaves / diameter of tree trunk |
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Term
| What is the connection between a gene and an allele? |
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Definition
| an allele is a form of a gene [e.g. there is a gene for tongue rolling ability with an allele for tongue rolling and an allele for not tongue rolling] |
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Term
| What is the connection between a genotype and an phenotype? |
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Definition
| the genotype of an organism causes its phenotype [e.g. with a genotype of Bb for eye colour the phenotype will be brown eyes] |
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Term
| Which type of allele is ALWAYS expressed in the phenotype? |
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Definition
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Term
| Which type of allele can be masked in the phenotype? |
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Definition
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Term
| Write two homozygous genotypes and one heterozygous geneotype. |
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Definition
| homozygous = HH & hh, heterozygous = Hh |
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Term
| What do the letters P, F1 and F2 mean? |
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Definition
| the generations in a family, P = parents, F1 = first generation of offspring, F2 = second generationof parents. |
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Term
| What is the phenotype ratio from a cross of two heterozygous parents? |
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Definition
| 3 dominant trait : 1 recessive trait |
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Term
| What is the phenotype ratio from a cross of one heterozygous parent and one homozygous recessive parent? |
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Definition
| 1 dominant trait : 1 recessive trait |
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Term
| What is the phenotype ratio from a cross of one homozygous dominant parent and one homozygous recessive parent? |
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Definition
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Term
| How you you calculate a percentage? |
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Definition
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Term
| In a family tree, explain why some offspring can have a different phenotype to either parent. |
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Definition
| the parents are both heterozygous with the dominant trait and the offspring have inherited two recessive alleles so have the recessive trait. |
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Term
| Why are predicted ratios not necessarily the same as actual ratios in a genetic cross? |
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Definition
| Fertilisation is a random event |
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