2.5 variation and inheritance
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give examples of variation
• peppered moth during the industrial revolution • different eye colours • height etc.
what is discrete variation?
Where a characteristic falls into distinct groups
What is continuous variation?
where a characteristic can have any value in range.
What are single gene traits controlled by and what type of variation do they show?
they are controlled by one gene and show discrete variation
What are polygenic traits controlled by and what type fo variation do they show?
they are controlled by many genes and show continuous variation
Give examples of polygenic traits
Height, skin colour, hair colour, eye colour
Give examples of single gene traits
tongue curling, hitch hikers thumb, attached or detached earlobes
Which genes will always show in the appearance of an organism if it is present?
the dominant genes will always show in the appearance of the organism even if there is only one copy.
Which genes needs two copies of itself to show in the appearance of an organism?
recessive genes need two copies of them to show in the appearance of the organism
What is the phenotype of an organism?
The appearance of the organism
What is sexual reproduction?
the combining of genes from two parents. this process contributes to variation within a species.
Give examples of phenotypes
• eye colour • hair colour • height
What is the genotype?
describes the set of genes an organism possesses
What is the genotype of a homozygous individual?
they have two matching alleles of one gene
What is the genotype of a heterozygous individual?
they have two different alleles of one gene
What is a carrier?
a person who has one copy of a diseased allele but is not affected by the disease
What are carriers at risk of?
passing on a genetic disorder to their offspring. they may receive genetic counselling.