Let's solve each Punnett square step by step and fill in the offspring genotypes, then determine their phenotypes and ratios where needed.
---
Key Definitions:
-
T = Tall (dominant allele)
-
t = Short (recessive allele)
-
TT = Homozygous dominant →
Tall
-
Tt = Heterozygous (mixed hybrid) →
Tall (because T is dominant)
-
tt = Homozygous recessive →
Short
We'll go through each of the four Punnett squares.
---
##
✔ 1. Both parents are dominant tall (TT × TT)
```
T T
-----------
T | TT TT
-----------
T | TT TT
-----------
```
All four boxes =
TT
Offspring:
1. TT
2. TT
3. TT
4. TT
✔ All offspring are
TT, so all are
tall.
>
Answer:
1. TT
2. TT
3. TT
4. TT
---
##
✔ 2. Both parents are mixed hybrid (Tt × Tt)
```
T t
-----------
T | TT Tt
-----------
t | Tt tt
-----------
```
The four possible genotypes:
1. TT
2. Tt
3. Tt
4. tt
Now, let’s name them:
- TT → Tall
- Tt → Tall
- Tt → Tall
- tt → Short
So, phenotypic ratio:
3 Tall : 1 Short
>
Answer:
1. TT
2. Tt
3. Tt
4. tt
Expected ratio: 3 Tall : 1 Short
---
##
✔ 3. One parent is dominant tall (TT), one is mixed hybrid (Tt)
```
T T
-----------
T | TT TT
-----------
t | Tt Tt
-----------
```
Genotypes:
1. TT
2. TT
3. Tt
4. Tt
All have at least one
T, so all are
Tall.
>
Answer:
1. TT
2. TT
3. Tt
4. Tt
(All offspring are tall)
---
##
✔ 4. Both parents are recessive short (tt × tt)
```
t t
-----------
t | tt tt
-----------
t | tt tt
-----------
```
All four boxes =
tt
>
Answer:
1. tt
2. tt
3. tt
4. tt
All offspring are
short.
---
✔ Final Answers:
---
####
1. Both parents are dominant tall (TT × TT):
1. TT
2. TT
3. TT
4. TT
---
####
2. Both parents are mixed hybrid (Tt × Tt):
1. TT
2. Tt
3. Tt
4. tt
Expected ratio: 3 Tall : 1 Short
---
####
3. One parent is dominant tall (TT), one is mixed hybrid (Tt):
1. TT
2. TT
3. Tt
4. Tt
---
####
4. Both parents are recessive short (tt × tt):
1. tt
2. tt
3. tt
4. tt
---
📌 Summary Table:
| Parent Cross | Offspring Genotypes | Phenotype Ratio |
|--------------|---------------------|------------------|
| TT × TT | All TT | All Tall |
| Tt × Tt | TT, Tt, Tt, tt | 3 Tall : 1 Short |
| TT × Tt | TT, TT, Tt, Tt | All Tall |
| tt × tt | All tt | All Short |
This completes the Punnett square analysis! Let me know if you'd like a visual version or explanation for any part.
Parent Tip: Review the logic above to help your child master the concept of punnett squares worksheet.
