In a particular insect species, sex is determined by a single gene - VCE - SSCE Biology - Question 3 - 2002 - Paper 1
Question 3
In a particular insect species, sex is determined by a single gene. The male insect has the genotype Mm and the female insect is mm. This gene is linked to another g... show full transcript
Worked Solution & Example Answer:In a particular insect species, sex is determined by a single gene - VCE - SSCE Biology - Question 3 - 2002 - Paper 1
Step 1
What is meant by linked genes?
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Answer
Linked genes are genes that are located close to each other on the same chromosome and tend to be inherited together during meiosis. Their close proximity means that they do not assort independently, which affects the inheritance patterns observed in offspring.
Step 2
How many map units apart are the genes for body colour and sex determination?
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Answer
The genes for body colour and sex determination are 1 map unit apart, as indicated by the proportion of offspring produced.
Step 3
Using the symbol B for the allele for black body, and b for bronze body colour, write down the genotype for a homozygous black female.
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The genotype for a homozygous black female is BB.
Step 4
Using the symbol B for the allele for black body, and b for bronze body colour, write down the genotype for a bronze male.
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The genotype for a bronze male is Mb.
Step 5
Predict the phenotypes of the offspring that would be found in a cross between the two insects described in c.i. and c.ii.
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The phenotypes of the offspring from the cross would yield 100% black offspring because the homozygous black female (BB) crossed with a bronze male (Mb) will not produce any bronze offspring, given that black (B) is dominant over bronze (b).
