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In a rat population, three different fur colours can be observed - VCE - SSCE Biology - Question 7 - 2016 - Paper 1
Question 7
In a rat population, three different fur colours can be observed. The rats can have grey, black or white fur. The production of fur colour pigment in these rats is ... show full transcript
Worked Solution & Example Answer:In a rat population, three different fur colours can be observed - VCE - SSCE Biology - Question 7 - 2016 - Paper 1
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c. What are the possible genotypes and phenotypes of the offspring? Show your working and state the ratio for the phenotypes of the offspring.
Answer
To find the possible genotypes of the offspring from the cross between two rats (GgAa x GgAa), we can use a Punnett square:
| GA | Ga | gA | ga | |
|---|---|---|---|---|
| GA | GGAa | GGaa | GgAA | GgAa |
| Ga | GGAa | GGaa | GgAA | GgAa |
| gA | GgAA | GgAa | ggAA | ggAa |
| ga | GgAa | GgAA | ggAa | ggaa |
From this Punnett square, we can derive the possible offspring genotypes: GGAa, GGaa, GgAA, GgAa, ggAA, ggAa, and ggaa.
Phenotypes of offspring:
- Grey: 9 (GGAa, GgAA, GgAa)
- Black: 3 (GGaa, ggAA)
- White: 4 (gaa)
Phenotypic ratio: 9 grey : 3 black : 4 white.