SSCE VCE Biology Genetic Diversity and Adaptations: In a particular insect species,

Question

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 gene that determines the body colour of the insect.

a. What is meant by linked genes?

The linked gene determining body colour in these insects has two phenotypes, black body colour and bronze body colour. Black body colour is the dominant phenotype.

When a heterozygous black male was crossed with a bronze female the following offspring were produced.

|              | Black male | Black female | Bronze male | Bronze female |
|--------------|------------|--------------|-------------|---------------|
| Number      | 47         | 3            | 3           | 47            |

b. How many map units apart are the genes for body colour and sex determination?

1 mark

c. Using the symbol B for the allele for black body, and b for bronze body colour, write down the genotype for a

i.  homozygous black female.

________________________________

ii. bronze male,

________________________________

1 + 1 = 2 marks

d. Predict the phenotypes of the offspring that would be found in a cross between the two insects described in c.i. and c.ii.

In a particular insect species, sex is determined by a single gene - VCE - SSCE Biology - Question 3 - 2002 - Paper 1

Worked Solution & Example Answer:In a particular insect species, sex is determined by a single gene - VCE - SSCE Biology - Question 3 - 2002 - Paper 1

What is meant by linked genes?

How many map units apart are the genes for body colour and sex determination?

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.

bronze male

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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