Punnett Square Practice: Codominance and Incomplete Dominance - Free Printable

Problem Overview:

The task involves completing Punnett squares for different genetic crosses involving incomplete dominance in flower color. The genotypes and phenotypes are provided, and we need to determine the percentages of offspring with specific traits and the ratios of different phenotypes.

#### Key Information:
- Genotypes:
- R (Red pigment)
- r (White pigment)
- Phenotypes:
- RR: Red flowers
- rr: White flowers
- Rr: Pink flowers (incomplete dominance)

#### Task:
1. Complete the Punnett squares for each cross.
2. Answer the questions based on the Punnett squares.

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Step-by-Step Solution:

#### Cross 1: Rxrr
- Parents: R (heterozygous, Rr) × rr (homozygous recessive)
- Punnett Square:

| | r | r |
|---|----|----|
| R | Rr | Rr |
| r | rr | rr |

- Offspring Genotypes: Rr, Rr, rr, rr
- Offspring Phenotypes:
- Rr: Pink flowers (2 out of 4)
- rr: White flowers (2 out of 4)

Answers:
1. What percentage of the offspring will have pink flowers?
- 50% (2 out of 4)

2. What percentage of the offspring will have red flowers?
- 0% (none)

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#### Cross 2: RxRr
- Parents: R (heterozygous, Rr) × Rr (heterozygous)
- Punnett Square:

| | R | r |
|---|----|----|
| R | RR | Rr |
| r | Rr | rr |

- Offspring Genotypes: RR, Rr, Rr, rr
- Offspring Phenotypes:
- RR: Red flowers (1 out of 4)
- Rr: Pink flowers (2 out of 4)
- rr: White flowers (1 out of 4)

Answers:
3. What percentage of the offspring will have white flowers?
- 25% (1 out of 4)

4. What percentage of the offspring will have pink flowers?
- 50% (2 out of 4)

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#### Cross 3: rxRR
- Parents: r (homozygous recessive, rr) × RR (homozygous dominant)
- Punnett Square:

| | R | R |
|---|----|----|
| r | Rr | Rr |

- Offspring Genotypes: Rr, Rr
- Offspring Phenotypes:
- Rr: Pink flowers (2 out of 2)

Answers:
5. What percentage of the offspring will have red flowers?
- 0% (none)

6. What percentage of the offspring will have white flowers?
- 0% (none)

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#### Cross 4: rxRB
- Parents: r (homozygous recessive, rr) × RB (homozygous dominant, RR)
- Punnett Square:

| | R | R |
|---|----|----|
| r | Rr | Rr |

- Offspring Genotypes: Rr, Rr
- Offspring Phenotypes:
- Rr: Pink flowers (2 out of 2)

Answer:
7. What will be the ratio of red flowers to pink flowers?
- Since all offspring are pink (Rr), the ratio is 0:2 or simply 0:1.

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Final Answers:

1. 50%
2. 0%
3. 25%
4. 50%
5. 0%
6. 0%
7. 0:1

Boxed Final Answer:
\[
\boxed{50\%, 0\%, 25\%, 50\%, 0\%, 0\%, 0:1}
\]