Monohybrid Crosses Practice Worksheet for Genetics

1. PP x Pp
- Gametes: P, P from PP; P, p from Pp
- Punnett Square:
| | P | P |
|---|---|---|
| P | PP | PP |
| p | Pp | Pp |
- Genotype ratio: 1 PP : 1 Pp
- Phenotype ratio: All Purple (PP and Pp both result in Purple)
- Answer: 100% Purple

2. TT x Tt
- Gametes: T, T from TT; T, t from Tt
- Punnett Square:
| | T | T |
|---|---|---|
| T | TT | TT |
| t | Tt | Tt |
- Genotype ratio: 1 TT : 1 Tt
- Phenotype ratio: All Tall (TT and Tt both result in Tall)
- Answer: 100% Tall

3. Ss x Ss
- Gametes: S, s from each parent
- Punnett Square:
| | S | s |
|---|---|---|
| S | SS | Ss |
| s | Ss | ss |
- Genotype ratio: 1 SS : 2 Ss : 1 ss
- Phenotype ratio: 3 Smooth : 1 Wrinkled
- Answer: 3 Smooth : 1 Wrinkled

4. yy x yy
- Gametes: y, y from each parent
- Punnett Square:
| | y | y |
|---|---|---|
| y | yy | yy |
| y | yy | yy |
- Genotype ratio: 100% yy
- Phenotype ratio: 100% Green Seed
- Answer: 100% Green Seed

5. Gg x Gg
- Gametes: G, g from each parent
- Punnett Square:
| | G | g |
|---|---|---|
| G | GG | Gg |
| g | Gg | gg |
- Genotype ratio: 1 GG : 2 Gg : 1 gg
- Phenotype ratio: 3 Green Pod : 1 Yellow Pod
- Answer: 3 Green Pod : 1 Yellow Pod

6. Hybrid tall (Tt) x short (tt)
- Gametes: T, t from Tt; t, t from tt
- Punnett Square:
| | T | t |
|---|---|---|
| t | Tt | tt |
| t | Tt | tt |
- Genotype ratio: 2 Tt : 2 tt
- Phenotype ratio: 2 Tall : 2 Short → 1 Tall : 1 Short
- Answer: 1 Tall : 1 Short

7. Purebred tall (TT) x short (tt)
- Gametes: T, T from TT; t, t from tt
- Punnett Square:
| | T | T |
|---|---|---|
| t | Tt | Tt |
| t | Tt | Tt |
- Genotype ratio: 100% Tt
- Phenotype ratio: 100% Tall
- Answer: 100% Tall

8. Heterozygous yellow seed (Yy) x green seed (yy)
- Gametes: Y, y from Yy; y, y from yy
- Punnett Square:
| | Y | y |
|---|---|---|
| y | Yy | yy |
| y | Yy | yy |
- Genotype ratio: 2 Yy : 2 yy
- Phenotype ratio: 2 Yellow : 2 Green → 1 Yellow : 1 Green
- Answer: 1 Yellow : 1 Green

9. Hybrid green pod (Gg) x hybrid green pod (Gg)
- Gametes: G, g from each parent
- Punnett Square:
| | G | g |
|---|---|---|
| G | GG | Gg |
| g | Gg | gg |
- Genotype ratio: 1 GG : 2 Gg : 1 gg
- Phenotype ratio: 3 Green Pod : 1 Yellow Pod
- Answer: 3 Green Pod : 1 Yellow Pod

10. Hybrid tall (Tt) x purebred tall (TT)
- Gametes: T, t from Tt; T, T from TT
- Punnett Square:
| | T | T |
|---|---|---|
| T | TT | TT |
| t | Tt | Tt |
- Genotype ratio: 2 TT : 2 Tt
- Phenotype ratio: 100% Tall
- Answer: 100% Tall

11. Purebred purple flowers (PP) x white flowers (pp)
- Gametes: P, P from PP; p, p from pp
- Punnett Square:
| | P | P |
|---|---|---|
| p | Pp | Pp |
| p | Pp | Pp |
- Genotype ratio: 100% Pp
- Phenotype ratio: 100% Purple
- Answer: 100% Purple

12. Hybrid purple flowers (Pp) x white flowers (pp)
- Gametes: P, p from Pp; p, p from pp
- Punnett Square:
| | P | p |
|---|---|---|
| p | Pp | pp |
| p | Pp | pp |
- Genotype ratio: 2 Pp : 2 pp
- Phenotype ratio: 2 Purple : 2 White → 1 Purple : 1 White
- Answer: 1 Purple : 1 White

13. Heterozygous purple flowers (Pp) x white flowers (pp)
- Gametes: P, p from Pp; p, p from pp
- Punnett Square:
| | P | p |
|---|---|---|
| p | Pp | pp |
| p | Pp | pp |
- Genotype ratio: 2 Pp : 2 pp
- Phenotype ratio: 2 Purple : 2 White → 1 Purple : 1 White
- Answer: 1 Purple : 1 White

14. Hybrid smooth seeds (Ss) x hybrid smooth seeds (Ss)
- Gametes: S, s from each parent
- Punnett Square:
| | S | s |
|---|---|---|
| S | SS | Ss |
| s | Ss | ss |
- Genotype ratio: 1 SS : 2 Ss : 1 ss
- Phenotype ratio: 3 Smooth : 1 Wrinkled
- Answer: 3 Smooth : 1 Wrinkled

15. Short plant (tt) x short plant (tt)
- Gametes: t, t from each parent
- Punnett Square:
| | t | t |
|---|---|---|
| t | tt | tt |
| t | tt | tt |
- Genotype ratio: 100% tt
- Phenotype ratio: 100% Short
- Answer: 100% Short