B1 Variation and Inheritance

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What are variations?
Differences between individual of the same species
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Why do genetic variations occur?
because individuals inherit different combinations of genes
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What can genetic inheritance be caused by?
mutations (changes the the genes), differences between individual gametes (ie. eggs and sperm), the random nature of fertilisation
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what can varations other than genetic be?
environmental
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What are two examples of genetic variation?
nose shape and eye colour
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What are two examples of environmental variation?
language and scars
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What are three examples of combination variation?
body mass, intelligence and height
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Where are all the instructions to make an individual held?
on chromosomes kept in the nucleus of all body cells
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What is the section of chromosome which codes for an inherited characteristic or protein called?
a gene
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How many pairs of chromosomes does a person have?
23
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How many chromosomes do gametes?
gametes have half the number of chromosomes of normal body cells
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What are the different versions of genes called?
alleles
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What are alleles that control characteristics described as being dominant or or recessive?
dominant or recessive
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What do dominant alleles control?
the development of a characteristic even if present on only one chromosome in a pair
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What do recessive alleles control?
the development of a characteristic only if a dominant allele isn't present
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What is the person described as if both chromosomes in a pair contain the same allele of a gene?
homozygous for that gene or condition
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What is the person described as if the chromosomes in a pair contain different alleles?
heterozygous for that gene or condition
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What is a monohybird inheritance?
when a characteristic is determined by just one pair of alleles, as with eye colour and tounge rolling
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What are capital letters used to represent?
dominant
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What are lower case letters used to represent?
recessive
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What are letters to describe the genetic make-up called?
genotype
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Gender (in mammals) is determined by the what?
sex
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What do egg cells carry?
all X chromosomes
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What do sperm cells carry?
half carry X and half carry Y chromosomes
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What is the sex of an individual depend on?
whether the egg is fertilised by an X- or Y- carrying sperm
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An egg fertilised by an X sperm will become a what?
girl (X from egg and X from sperm = XX)
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An egg fertilised by an Y sperm will become a what?
boy (X from egg and Y from sperm = XY)
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What is the chance of having a girl or boy?
50:50
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If a disease is caused by a 'faulty' gene then what can they be?
inherited
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What is three examples of 'faulty' gene diseases?
red-green colourblindness, sickle cell anaemia, cystic fibrosis
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Why may having an inherited disease create issues?
may not know whether to have kids, or to abort an affected foetus
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What are inherited disorders are mostly caused by?
recessive faulty genes
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What does it mean that the gene for cystic fibrosis is recessive?
that offspring will only have the disorder if both genes are faulty
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Other cards in this set

Card 2

Front

Why do genetic variations occur?

Back

because individuals inherit different combinations of genes

Card 3

Front

What can genetic inheritance be caused by?

Back

Preview of the front of card 3

Card 4

Front

what can varations other than genetic be?

Back

Preview of the front of card 4

Card 5

Front

What are two examples of genetic variation?

Back

Preview of the front of card 5
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