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A student completed a genetics exercise by preparing the Punnett square drawn below - HSC - SSCE Biology - Question 5 - 2006 - Paper 1
Question 5
A student completed a genetics exercise by preparing the Punnett square drawn below. T represents a dominant allele and t represents a recessive allele. ... show full transcript
Worked Solution & Example Answer:A student completed a genetics exercise by preparing the Punnett square drawn below - HSC - SSCE Biology - Question 5 - 2006 - Paper 1
Step 1
What were the likely genotypes of the parents?
Answer
To determine the likely genotypes of the parents based on the Punnett square:
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Understanding the Punnett Square: The Punnett square shows the possible genetic outcomes from two parents. In this case, we can see the gametes of Parent 1 and Parent 2.
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Analyzing Parent 1 Gametes: The gametes of Parent 1 show that there is a 'TT' genotype and 'Tt' genotype, suggesting that Parent 1 is either homozygous dominant (TT) or heterozygous (Tt).
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Analyzing Parent 2 Gametes: The gametes of Parent 2 show 'Tt' and 'tt', indicating Parent 2 is heterozygous (Tt) and homozygous recessive (tt).
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Confirming Genotypes Based on Offspring: Given that all offspring possibilities resulting from these parents consist of both dominant and recessive phenotypes, it indicates that Parent 1 must be heterozygous to support the presence of a 'tt' offspring from Parent 2 along with other combinations.
Based on this analysis, the answer is (C) Both parents were heterozygous.