Let’s solve each Punnett Square step by step.
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First Square (Top Left):
Both parents are dominant tall → genotype TT x TT
Each parent can only give a “T” allele.
So all offspring will be:
- Top left: T from mom + T from dad = TT
- Top right: T from mom + T from dad = TT
- Bottom left: T from mom + T from dad = TT
- Bottom right: T from mom + T from dad = TT
→ All 4 offspring are
TT
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Second Square (Top Right):
Both parents are mixed hybrids → genotype Tt x Tt
Parent 1 (top) gives: T or t
Parent 2 (side) gives: T or t
Fill the squares:
- Top left: T + T = TT
- Top right: T + t = Tt
- Bottom left: t + T = Tt
- Bottom right: t + t = tt
→ Offspring: TT, Tt, Tt, tt
Phenotypes:
- TT → tall
- Tt → tall (mixed hybrid, but still tall)
- tt → short
So ratio of tall to short = 3 tall : 1 short
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Third Square (Bottom Left):
One parent is dominant tall (TT), one is mixed hybrid (Tt)
Parent 1 (top): T, T
Parent 2 (side): T, t
Fill the squares:
- Top left: T + T = TT
- Top right: T + T = TT
- Bottom left: T + t = Tt
- Bottom right: T + t = Tt
→ Offspring: TT, TT, Tt, Tt
All are tall (since TT and Tt both result in tall phenotype)
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Fourth Square (Bottom Right):
Both parents are recessive short → genotype tt x tt
Each parent can only give “t”
So all offspring:
- All four squares: t + t = tt
→ All 4 offspring are
tt
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Now let’s write the answers clearly for each section.
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Final Answer:
Top Left Square (TT x TT):
1. TT
2. TT
3. TT
4. TT
Top Right Square (Tt x Tt):
1. TT
2. Tt
3. Tt
4. tt
Expected ratio of tall to short: 3:1
Bottom Left Square (TT x Tt):
1. TT
2. TT
3. Tt
4. Tt
Bottom Right Square (tt x tt):
1. tt
2. tt
3. tt
4. tt
Parent Tip: Review the logic above to help your child master the concept of punnett squares worksheet.
