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What does a gene carry instructions for?
Making a protein or controlling a trait
Where are genes found in a cell?
On chromosomes in the nucleus
How many copies of each gene do you inherit?
Two — one from each parent
Give an example of two alleles for eye colour
Brown (B) and blue (b)
How are alleles related to genes?
Alleles are different forms of the same gene
If a plant has alleles T and t for height, what does each allele represent?
T = tall, t = short
If an organism’s alleles are Bb, what is its genotype?
Bb
Can two organisms have the same phenotype but different genotypes?
Yes — BB and Bb both produce the same dominant trait
How do you write a genotype for a recessive trait?
Using two lowercase letters, e.g. bb
What is the phenotype of a mouse with alleles bb for fur colour (b = white)?
White fur
Which is visible — genotype or phenotype?
Phenotype
Give an example of a homozygous dominant genotype
BB
Give an example of a homozygous recessive genotype
bb
If an organism’s genotype is Tt, is it heterozygous or homozygous?
Heterozygous
Why does a heterozygous individual show the dominant trait?
The dominant allele masks the recessive one
Can a heterozygous individual pass on a recessive allele?
Yes — it carries one copy of the recessive allele
