Punnett Square Monohybrid Cross Worksheets - Free Printable

Problem Overview:

The task involves solving monohybrid crosses using Punnett squares. A monohybrid cross examines the inheritance of a single trait. The key provided in the image defines the alleles for different traits (e.g., tall/short, yellow/green seed, etc.). We will solve each problem step by step.

---

Key Information:

- Dominant allele: Capital letter (e.g., T, G, Y, S, P)
- Recessive allele: Lowercase letter (e.g., t, g, y, s, p)
- Phenotype ratios:
- Dominant phenotype: Any combination with at least one dominant allele (e.g., TT, Tt)
- Recessive phenotype: Only recessive alleles (e.g., tt)

---

Solutions:

#### 1. PP x Pp
- Traits: Purple flower (P = Purple, p = White)
- Parents: PP (homozygous dominant), Pp (heterozygous)
- Gametes:
- Parent 1 (PP): P
- Parent 2 (Pp): P, p
- Punnett Square:
```
| P | p
--|----|----
P | PP | Pp
--|----|----
P | PP | Pp
```
- Genotypes: PP, PP, Pp, Pp
- Phenotypes: All purple flowers (no white flowers)
- Phenotype ratio: 4 Purple : 0 White

---

#### 2. TT x Tt
- Traits: Tall plant (T = Tall, t = Short)
- Parents: TT (homozygous dominant), Tt (heterozygous)
- Gametes:
- Parent 1 (TT): T
- Parent 2 (Tt): T, t
- Punnett Square:
```
| T | t
--|----|----
T | TT | Tt
--|----|----
T | TT | Tt
```
- Genotypes: TT, TT, Tt, Tt
- Phenotypes: All tall plants (no short plants)
- Phenotype ratio: 4 Tall : 0 Short

---

#### 3. Ss x Ss
- Traits: Smooth seed (S = Smooth, s = Wrinkled)
- Parents: Ss (heterozygous), Ss (heterozygous)
- Gametes:
- Parent 1 (Ss): S, s
- Parent 2 (Ss): S, s
- Punnett Square:
```
| S | s
--|----|----
S | SS | Ss
--|----|----
s | Ss | ss
```
- Genotypes: SS, Ss, Ss, ss
- Phenotypes: 3 smooth seeds, 1 wrinkled seed
- Phenotype ratio: 3 Smooth : 1 Wrinkled

---

#### 4. yy x yy
- Traits: Yellow seed (y = Yellow, Y = Green)
- Parents: yy (homozygous recessive), yy (homozygous recessive)
- Gametes:
- Parent 1 (yy): y
- Parent 2 (yy): y
- Punnett Square:
```
| y
--|---
y | yy
--|---
y | yy
```
- Genotypes: yy, yy
- Phenotypes: All yellow seeds
- Phenotype ratio: 4 Yellow : 0 Green

---

#### 5. Gg x Gg
- Traits: Green pod (G = Green, g = Yellow)
- Parents: Gg (heterozygous), Gg (heterozygous)
- Gametes:
- Parent 1 (Gg): G, g
- Parent 2 (Gg): G, g
- Punnett Square:
```
| G | g
--|----|----
G | GG | Gg
--|----|----
g | Gg | gg
```
- Genotypes: GG, Gg, Gg, gg
- Phenotypes: 3 green pods, 1 yellow pod
- Phenotype ratio: 3 Green : 1 Yellow

---

#### 6. hybrid tall x short
- Traits: Tall plant (T = Tall, t = Short)
- Parents: Tt (heterozygous), tt (homozygous recessive)
- Gametes:
- Parent 1 (Tt): T, t
- Parent 2 (tt): t
- Punnett Square:
```
| t
--|---
T | Tt
--|---
t | tt
```
- Genotypes: Tt, tt
- Phenotypes: 1 tall plant, 1 short plant
- Phenotype ratio: 1 Tall : 1 Short

---

#### 7. purebred tall x short
- Traits: Tall plant (T = Tall, t = Short)
- Parents: TT (homozygous dominant), tt (homozygous recessive)
- Gametes:
- Parent 1 (TT): T
- Parent 2 (tt): t
- Punnett Square:
```
| t
--|---
T | Tt
--|---
T | Tt
```
- Genotypes: Tt, Tt
- Phenotypes: All tall plants
- Phenotype ratio: 2 Tall : 0 Short

---

#### 8. heterozygous yellow seed x hybrid green pod
- Traits: Yellow seed (y = Yellow, Y = Green) and Green pod (G = Green, g = Yellow)
- Parents: yy (homozygous recessive for seed color), Gg (heterozygous for pod color)
- Gametes:
- Parent 1 (yy): y
- Parent 2 (Gg): G, g
- Punnett Square:
```
| G | g
--|----|----
y | yG | yg
--|----|----
y | yG | yg
```
- Genotypes: yG, yg, yG, yg
- Phenotypes:
- Seed color: All yellow seeds (yy)
- Pod color: 2 green pods, 2 yellow pods
- Phenotype ratio:
- Seed color: 4 Yellow : 0 Green
- Pod color: 2 Green : 2 Yellow

---

#### 9. hybrid green pod x purebred tall
- Traits: Green pod (G = Green, g = Yellow) and Tall plant (T = Tall, t = Short)
- Parents: Gg (heterozygous for pod color), TT (homozygous dominant for height)
- Gametes:
- Parent 1 (Gg): G, g
- Parent 2 (TT): T
- Punnett Square:
```
| T | T
--|----|----
G | GT | GT
--|----|----
g | Tg | Tg
```
- Genotypes: GT, GT, Tg, Tg
- Phenotypes:
- Pod color: 2 green pods, 2 yellow pods
- Height: All tall plants
- Phenotype ratio:
- Pod color: 2 Green : 2 Yellow
- Height: 4 Tall : 0 Short

---

#### 10. hybrid tall x purebred tall
- Traits: Tall plant (T = Tall, t = Short)
- Parents: Tt (heterozygous), TT (homozygous dominant)
- Gametes:
- Parent 1 (Tt): T, t
- Parent 2 (TT): T
- Punnett Square:
```
| T | T
--|----|----
T | TT | TT
--|----|----
t | Tt | Tt
```
- Genotypes: TT, TT, Tt, Tt
- Phenotypes: All tall plants
- Phenotype ratio: 4 Tall : 0 Short

---

#### 11. purebred purple flowers x white flowers
- Traits: Purple flower (P = Purple, p = White)
- Parents: PP (homozygous dominant), pp (homozygous recessive)
- Gametes:
- Parent 1 (PP): P
- Parent 2 (pp): p
- Punnett Square:
```
| p
--|---
P | Pp
--|---
P | Pp
```
- Genotypes: Pp, Pp
- Phenotypes: All purple flowers
- Phenotype ratio: 2 Purple : 0 White

---

#### 12. hybrid purple flowers x white flowers
- Traits: Purple flower (P = Purple, p = White)
- Parents: Pp (heterozygous), pp (homozygous recessive)
- Gametes:
- Parent 1 (Pp): P, p
- Parent 2 (pp): p
- Punnett Square:
```
| p
--|---
P | Pp
--|---
p | pp
```
- Genotypes: Pp, pp
- Phenotypes: 1 purple flower, 1 white flower
- Phenotype ratio: 1 Purple : 1 White

---

#### 13. heterozygous purple flowers x white flowers
- Traits: Purple flower (P = Purple, p = White)
- Parents: Pp (heterozygous), pp (homozygous recessive)
- Gametes:
- Parent 1 (Pp): P, p
- Parent 2 (pp): p
- Punnett Square:
```
| p
--|---
P | Pp
--|---
p | pp
```
- Genotypes: Pp, pp
- Phenotypes: 1 purple flower, 1 white flower
- Phenotype ratio: 1 Purple : 1 White

---

#### 14. hybrid smooth seeds x hybrid smooth seeds
- Traits: Smooth seed (S = Smooth, s = Wrinkled)
- Parents: Ss (heterozygous), Ss (heterozygous)
- Gametes:
- Parent 1 (Ss): S, s
- Parent 2 (Ss): S, s
- Punnett Square:
```
| S | s
--|----|----
S | SS | Ss
--|----|----
s | Ss | ss
```
- Genotypes: SS, Ss, Ss, ss
- Phenotypes: 3 smooth seeds, 1 wrinkled seed
- Phenotype ratio: 3 Smooth : 1 Wrinkled

---

#### 15. short plant x short plant
- Traits: Tall plant (T = Tall, t = Short)
- Parents: tt (homozygous recessive), tt (homozygous recessive)
- Gametes:
- Parent 1 (tt): t
- Parent 2 (tt): t
- Punnett Square:
```
| t
--|---
t | tt
--|---
t | tt
```
- Genotypes: tt, tt
- Phenotypes: All short plants
- Phenotype ratio: 4 Short : 0 Tall

---

Final Answer:

Each Punnett square and its corresponding phenotype ratios are calculated above. The solutions are boxed as follows:

\boxed{
\begin{aligned}
&\text{1. } 4 \text{ Purple : 0 White} \\
&\text{2. } 4 \text{ Tall : 0 Short} \\
&\text{3. } 3 \text{ Smooth : 1 Wrinkled} \\
&\text{4. } 4 \text{ Yellow : 0 Green} \\
&\text{5. } 3 \text{ Green : 1 Yellow} \\
&\text{6. } 1 \text{ Tall : 1 Short} \\
&\text{7. } 2 \text{ Tall : 0 Short} \\
&\text{8. } 4 \text{ Yellow seeds, 2 Green pods : 2 Yellow pods} \\
&\text{9. } 4 \text{ Tall, 2 Green pods : 2 Yellow pods} \\
&\text{10. } 4 \text{ Tall : 0 Short} \\
&\text{11. } 2 \text{ Purple : 0 White} \\
&\text{12. } 1 \text{ Purple : 1 White} \\
&\text{13. } 1 \text{ Purple : 1 White} \\
&\text{14. } 3 \text{ Smooth : 1 Wrinkled} \\
&\text{15. } 4 \text{ Short : 0 Tall}
\end{aligned}
}