Question

1. in a person with the i^a i genotype, which allele is dominant, i^a or i?
2. codominance occurs when both alleles are dominant. which of the genotypes results in a codominant blood type?

were the babies switched?
now you are ready to evaluate whether the baby girls were switched. the following family trees show the blood types for each person in both families.
family tree diagrams: one family has earnest (a), tonja (o), denise (b); another family has michael (ab), danielle (o), michelle (a), michael jr. (b)

Explanation:

Question 2

Step1: Recall Blood Type Alleles

Blood type alleles: \( I^A \), \( I^B \) (dominant), \( i \) (recessive). Genotype \( I^A i \): \( I^A \) is dominant over \( i \), so phenotype is A.

Step2: Determine Dominant Allele

In \( I^A i \), \( I^A \) expresses (A blood type), \( i \) is masked. So \( I^A \) is dominant over \( i \).

Step1: Define Codominance

Codominance: Both alleles expressed (e.g., \( I^A I^B \) gives AB blood, both \( I^A \) and \( I^B \) show).

Step2: Identify Codominant Genotype

Genotype \( I^A I^B \) results in codominance (AB blood, both alleles dominant and expressed). Genotypes like \( I^A I^A \), \( I^A i \), \( I^B I^B \), \( I^B i \), \( ii \) are not codominant (only one allele or recessive expressed).

Step1: Analyze Earnest/Tonja Family

Earnest (A, possible \( I^A I^A \) or \( I^A i \)), Tonja (O, \( ii \)). Possible offspring: \( I^A i \) (A) or \( ii \) (O). Denise is B (needs \( I^B \) allele, but Tonja has only \( i \), Earnest has no \( I^B \) (A or O genotype) → Denise (B) cannot be their biological child (no \( I^B \) source).

Step2: Analyze Michael/Danielle Family

Michael (AB, \( I^A I^B \)), Danielle (O, \( ii \)). Possible offspring: \( I^A i \) (A) or \( I^B i \) (B). Michelle (A, \( I^A i \) possible), Michael Jr. (B, \( I^B i \) possible) → Michael Jr. (B) and Denise (B) – Denise should be Michael/Danielle’s, Michael Jr. should be Earnest/Tonja’s? Wait, Earnest/Tonja can only have A or O. Wait, recheck:

• Earnest (A: \( I^A i \) or \( I^A I^A \)), Tonja (O: \( ii \)) → Offspring alleles: \( I^A \) (from Earnest) and \( i \) (from Tonja) → only A (\( I^A i \)) or O (\( ii \)). Denise is B (needs \( I^B \)), impossible.
• Michael (AB: \( I^A I^B \)), Danielle (O: \( ii \)) → Offspring: \( I^A i \) (A) or \( I^B i \) (B). Michelle (A: \( I^A i \) possible), Michael Jr. (B: \( I^B i \) possible).
• So Denise (B) must belong to Michael/Danielle (can produce B), and Michael Jr. (B) cannot belong to Earnest/Tonja (can’t produce B). Wait, no—Earnest/Tonja can’t have B, so Denise (B) is not theirs. Michael/Danielle can have B (Michael Jr. is B, which is possible). But Denise is B (from Earnest/Tonja? No). So Denise (B) and Michael Jr. (B) – likely switched, because Earnest/Tonja can’t have B, but Michael/Danielle can have B. Wait, re-express:
• Earnest (A) × Tonja (O): Offspring must be A (\( I^A i \)) or O (\( ii \)). Denise is B → not possible.
• Michael (AB) × Danielle (O): Offspring can be A (\( I^A i \)) or B (\( I^B i \)). Michelle (A) is possible, Michael Jr. (B) is possible.
• So Denise (B) is not Earnest/Tonja’s, Michael Jr. (B) is Michael/Danielle’s. But Denise is with Earnest/Tonja, Michael Jr. with Michelle/Michael. Thus, babies were switched (Denise should be with Michael/Danielle, Michael Jr. can’t be with Earnest/Tonja, but Denise is there incorrectly).

Answer:

\( I^A \) is dominant over \( i \).

Question 3