SOLUTION: Worksheet non mendelian genetics multiple alleles ... - Free Printable

Let’s solve each problem step by step using Punnett squares. We’re working with blood types, which are controlled by three alleles: I^A, I^B, and i (which is the same as “O”). Remember:

- I^A and I^B are dominant over i.
- I^A and I^B are codominant — if you have both, your blood type is AB.
- Type O only happens when you have two i alleles (ii).

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Problem 1:

Drake is homozygous for B allele → that means his genotype is I^B I^B
Ana is type O → her genotype is i i

We make a Punnett square:

Put Drake’s alleles on top: I^B | I^B
Put Ana’s alleles on side: i | i

Fill in the boxes:

Top-left: I^B + i = I^B i
Top-right: I^B + i = I^B i
Bottom-left: I^B + i = I^B i
Bottom-right: I^B + i = I^B i

All four babies will be I^B i

Phenotype? Since I^B is dominant over i, all babies will have Type B blood.

✔ GENOTYPE: All I^B i
✔ PHENOTYPE: All Type B

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Problem 2:

Robbin is heterozygous for A allele → that means I^A i
Sheena is type O → i i

Punnett square:

Robbin’s alleles on top: I^A | i
Sheena’s alleles on side: i | i

Boxes:

Top-left: I^A + i = I^A i
Top-right: i + i = i i
Bottom-left: I^A + i = I^A i
Bottom-right: i + i = i i

So genotypes:
→ Two I^A i
→ Two i i

Phenotypes:
→ I^A i = Type A
→ i i = Type O

✔ GENOTYPE: 50% I^A i, 50% i i
✔ PHENOTYPE: 50% Type A, 50% Type O

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Problem 3:

Mother is type O → i i
Father is type AB → I^A I^B

Punnett square:

Father’s alleles on top: I^A | I^B
Mother’s alleles on side: i | i

Boxes:

Top-left: I^A + i = I^A i
Top-right: I^B + i = I^B i
Bottom-left: I^A + i = I^A i
Bottom-right: I^B + i = I^B i

Genotypes:
→ Two I^A i
→ Two I^B i

Phenotypes:
→ I^A i = Type A
→ I^B i = Type B

✔ GENOTYPE: 50% I^A i, 50% I^B i
✔ PHENOTYPE: 50% Type A, 50% Type B

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Problem 4:

Mother: Type O → i i
Father: Type AB → I^A I^B
Baby: Type B → could be I^B i or I^B I^B

But let’s see what combinations are possible from these parents.

From Problem 3 above, we already know:

Parents: i i × I^A I^B → offspring can ONLY be I^A i (Type A) or I^B i (Type B)

So baby being Type B (I^B i) IS possible!

Wait — but the question says: “Two parents think their baby was switched...”

If the baby has Type B blood, and the parents are Type O and Type AB, then YES — it’s genetically possible. The baby could be theirs.

Because:

- Mom gives only “i”
- Dad gives either “I^A” or “I^B”
- So baby gets either I^A i (Type A) or I^B i (Type B)

So if baby is Type B → genotype I^B i → totally possible.

Therefore, the baby was NOT necessarily switched. It’s biologically possible.

✔ Final conclusion: The baby COULD be theirs. No switch needed based on blood type alone.

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Final Answer:

1. GENOTYPE: All I^B i
PHENOTYPE: All Type B

2. GENOTYPE: 50% I^A i, 50% i i
PHENOTYPE: 50% Type A, 50% Type O

3. GENOTYPE: 50% I^A i, 50% I^B i
PHENOTYPE: 50% Type A, 50% Type B

4. Yes, the baby could be theirs — Type B (I^B i) is a possible child of a Type O (ii) mother and Type AB (I^A I^B) father.