Question

(e) explain a way you could determine the genotype of individual 13 (support your answer with punnett squares), and what would you have to do to be sure and why the genotype of individual 13 cannot be known from the chart (include a punnett square to support your answer.)

Explanation:

Why genotype of individual 13 is unknown from the chart

Individual 13 displays the dominant phenotype, meaning they could be homozygous dominant (\(AA\)) or heterozygous (\(Aa\)) because both parents are carriers (\(Aa \times Aa\)) or one is heterozygous and the other homozygous dominant, yielding a \(3:1\) or \(1:0\) dominant-to-recessive phenotypic ratio where dominant offspring genotypes cannot be distinguished by sight alone.

How to determine the genotype of individual 13

Perform a test cross by mating individual 13 with a homozygous recessive individual (\(aa\)).

Expected outcomes and Punnett squares

If individual 13 is \(AA\):

$$
LATEXBLOCK0
$$

Result: 100% dominant phenotype (\(Aa\)).

If individual 13 is \(Aa\):

$$
LATEXBLOCK1
$$

Result: 50% dominant (\(Aa\)) and 50% recessive (\(aa\)) phenotypes. To be absolutely sure, a large number of offspring must be produced without any showing the recessive phenotype.

Answer:

1. Why it cannot be known from the chart: Individual 13 has the dominant phenotype, which can result from either a homozygous dominant (\(AA\)) or heterozygous (\(Aa\)) genotype.

1. How to determine the genotype: Perform a test cross by mating individual 13 with a homozygous recessive individual (\(aa\)).

1. Punnett Squares & Outcomes:

• If 13 is \(AA\) (all offspring show dominant phenotype):

$$
LATEXBLOCK0
$$

• If 13 is \(Aa\) (approximately 50% of offspring show recessive phenotype):

$$
LATEXBLOCK1
$$

To be sure, you must observe a statistically significant number of offspring; if even one recessive offspring (\(aa\)) is born, individual 13 is definitely heterozygous (\(Aa\)).