Several male mice with bent tails were mated to female mice with straight tails - VCE - SSCE Biology - Question 3 - 2003 - Paper 1
Question 3
Several male mice with bent tails were mated to female mice with straight tails. All of the F1 males had straight tails and all of the F1 females had bent tails.
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Worked Solution & Example Answer:Several male mice with bent tails were mated to female mice with straight tails - VCE - SSCE Biology - Question 3 - 2003 - Paper 1
Step 1
A. the gene involved in this cross is autosomal.
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Answer
This statement is ambiguous. While it is possible that the gene is autosomal, there is no definitive evidence provided in the question to confirm whether the gene is located on an autosome or a sex chromosome.
Step 2
B. the female parent with a straight tail is heterozygous.
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Answer
Since all F1 males had straight tails and F1 females had bent tails, this indicates that the straight tail is dominant. Therefore, it is logical that the female parent must be homozygous for the straight tail allele.
Step 3
C. this cross demonstrates that bent tails is the recessive phenotype.
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Answer
In this scenario, since the F1 females exhibited bent tails while the F1 males showed straight tails, it can be concluded that bent tails is indeed the recessive phenotype.
Step 4
D. the F1 female is heterozygous.
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The F1 female must be heterozygous because she exhibits the recessive phenotype (bent tail), which can only result if she inherited one recessive allele (bent tail) from one parent and a dominant allele (straight tail) from the other.
