B1h - Variation and Inheritance

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What is Variation?
Variation is differences between individuals of the same species.
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What causes Genetic Variation?
Indiviuals can inherit different combinations of genes. It could be caused by mutations, differences between individual gametes or random nature of fertilisation.
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What characteristics are caused by both inheritance and environment?
Height, Intelligence, Body Mass
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Give examples of inherited disorders
Red-Green colour blindness, Sickle cell anaemia and cystic-fibrosis.
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What are Alleles?
Alleles are different versions of the same gene. Alleles are described to be either dominant or recessive.
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What is the importance of chromosomes in cells?
Chromosomes are held in the nucleus and carry information in the form of genes, which control inherited characteristics.
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How do dominant and recessive characteristics depend on dominant and recessive alleles?
Dominant alleles control the development of a characteristics even if present on only one chromosome in a pair. Recessive alleles control the development of a characteristic, only when the dominant allele is not present.
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What does the term 'Homozygous' mean?
Homozygous relates to the idea that both chromosomes in a pair contain the same allele of a gene.
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What does the term 'Heterozygous' mean?
Heterozygous relates to the idea that the chromosomes in a pair contain different alleles.
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What does the term 'Phenotype' mean?
Phenotype is the characteristic expressed. (e.g. brown eyes)
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What does the term 'Genotype' mean?
Genotype is the genetic make-up. (e.g BB)
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How is sex in mammals determined by sex chromosomes?
When an egg is fertilised by an X sperm, it is a girl (XX). When an egg is fertilised by an Y sperm, it is a boy (XY).
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What chromosomes do gametes carry?
Female Gametes, Eggs carry all X chromosomes. Male Gametes, Sperms, carry half X Chromosomes and half Y Chromosomes.
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What causes Inherited Disorders?
Inherited Disorders are caused by faulty alleles, most of which are recessive.
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What are some of the issues raised by families, in knowledge of inherited disorders?
Issues will be raised such as whether to have children or not, whether to abort an affect foetus.
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What is the Scientist debate over the greater influence?
Scientists currently debate whether genetics / environment has the greater influence in the development of characteristics such intelligence, health and sporting ability. It is unlikely that it is down to one factor.
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Card 2

Front

What causes Genetic Variation?

Back

Indiviuals can inherit different combinations of genes. It could be caused by mutations, differences between individual gametes or random nature of fertilisation.

Card 3

Front

What characteristics are caused by both inheritance and environment?

Back

Preview of the front of card 3

Card 4

Front

Give examples of inherited disorders

Back

Preview of the front of card 4

Card 5

Front

What are Alleles?

Back

Preview of the front of card 5
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