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With respect to the PKU gene locus, you could reasonably conclude that individual A - VCE - SSCE Biology - Question 1 - 2002 - Paper 1
Question 1
With respect to the PKU gene locus, you could reasonably conclude that individual A. I – 1 is homozygous. B. I – 2 is homozygous. C. II – 5 is heterozygous. D. I... show full transcript
Worked Solution & Example Answer:With respect to the PKU gene locus, you could reasonably conclude that individual A - VCE - SSCE Biology - Question 1 - 2002 - Paper 1
Step 1
A. I – 1 is homozygous.
Answer
To determine if individual I – 1 is homozygous, we examine the inheritance pattern in the family pedigree. If both parents contribute the same allele (either both recessive or both dominant), then individual I – 1 can be concluded to be homozygous. This situation usually appears if both parents show the same trait or if both alleles match, signifying that they are homozygous.
Step 2
B. I – 2 is homozygous.
Answer
Individual I – 2's genotype can also be assessed by looking at the alleles inherited from both parents. If there is no evidence of differing alleles from the parents represented in the pedigree and both express the same trait, we conclude that I – 2 is homozygous.
Step 3
C. II – 5 is heterozygous.
Answer
For individual II – 5 to be categorized as heterozygous, we must find that one allele is dominant and the other is recessive. If individual II – 5 displays a trait that indicates heterozygosity—i.e., showing the dominant trait while having a recessive parent or sibling—then we can conclude they are heterozygous.
Step 4
D. III – 1 is heterozygous.
Answer
Similarly, for III – 1 to be identified as heterozygous, this individual should demonstrate the presence of both a dominant and a recessive allele. Analyzing the family background and identifying how the traits are expressed in the individuals connected to III – 1 would allow us to reasonably conclude their genotype.