Monohybrid Crosses: Printable and digital worksheets for teaching genetics and Punnett squares.

The image contains a worksheet on Monohybrid Crosses, which is a fundamental concept in genetics. Monohybrid crosses involve the inheritance of a single trait, and Punnett squares are used to predict the genotypes and phenotypes of offspring. Below, I will solve the problems step by step and explain the solutions.

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Problem 22: Predict the genotype and phenotypic outcomes for the offspring of a cross between two heterozygous tall pea plants.

#### Given Information:
- Tall plants are dominant over short plants.
- Genotype for tall plants: \( T \) (dominant allele)
- Genotype for short plants: \( t \) (recessive allele)
- Heterozygous tall plants have the genotype \( Tt \).

#### Solution:
1. Identify the parents' genotypes:
- Both parents are heterozygous tall plants, so their genotypes are \( Tt \).

2. Set up the Punnett square:
- The alleles from one parent are written along the top row.
- The alleles from the other parent are written along the left column.
- The Punnett square will look like this:

| | \( T \) | \( t \) |
|----|---------|---------|
| \( T \) | \( TT \) | \( Tt \) |
| \( t \) | \( Tt \) | \( tt \) |

3. Determine the genotypes of the offspring:
- Possible genotypes: \( TT \), \( Tt \), \( Tt \), \( tt \).
- Ratio of genotypes: \( 1TT : 2Tt : 1tt \).

4. Determine the phenotypes of the offspring:
- \( TT \): Tall (dominant phenotype)
- \( Tt \): Tall (dominant phenotype)
- \( tt \): Short (recessive phenotype)
- Ratio of phenotypes: \( 3 \) Tall : \( 1 \) Short.

#### Final Answer:
- Genotypes: \( 1TT \), \( 2Tt \), \( 1tt \)
- Phenotypes: \( 3 \) Tall, \( 1 \) Short

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Problem 23: In pea plants, purple flowers are dominant to white flowers. A purebred purple flower is crossed with a white flower. Predict the genetic and phenotypic outcomes.

#### Given Information:
- Purple flowers are dominant over white flowers.
- Genotype for purple flowers: \( P \) (dominant allele)
- Genotype for white flowers: \( p \) (recessive allele)
- Purebred purple plant has the genotype \( PP \).
- White plant has the genotype \( pp \).

#### Solution:
1. Identify the parents' genotypes:
- Purebred purple plant: \( PP \)
- White plant: \( pp \)

2. Set up the Punnett square:
- The alleles from one parent are written along the top row.
- The alleles from the other parent are written along the left column.
- The Punnett square will look like this:

| | \( P \) | \( P \) |
|----|---------|---------|
| \( p \) | \( Pp \) | \( Pp \) |

3. Determine the genotypes of the offspring:
- Possible genotypes: \( Pp \), \( Pp \).
- All offspring have the genotype \( Pp \).

4. Determine the phenotypes of the offspring:
- \( Pp \): Purple (dominant phenotype)
- All offspring will have purple flowers.

#### Final Answer:
- Genotypes: \( Pp \) (all)
- Phenotypes: Purple (all)

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Problem 24: A heterozygous black fur rabbit is crossed with a white fur rabbit. Predict the genetic and phenotypic outcomes.

#### Given Information:
- Black fur is dominant over white fur.
- Genotype for black fur: \( B \) (dominant allele)
- Genotype for white fur: \( b \) (recessive allele)
- Heterozygous black fur rabbit has the genotype \( Bb \).
- White fur rabbit has the genotype \( bb \).

#### Solution:
1. Identify the parents' genotypes:
- Heterozygous black fur rabbit: \( Bb \)
- White fur rabbit: \( bb \)

2. Set up the Punnett square:
- The alleles from one parent are written along the top row.
- The alleles from the other parent are written along the left column.
- The Punnett square will look like this:

| | \( B \) | \( b \) |
|----|---------|---------|
| \( b \) | \( Bb \) | \( bb \) |

3. Determine the genotypes of the offspring:
- Possible genotypes: \( Bb \), \( bb \).
- Ratio of genotypes: \( 1Bb : 1bb \).

4. Determine the phenotypes of the offspring:
- \( Bb \): Black (dominant phenotype)
- \( bb \): White (recessive phenotype)
- Ratio of phenotypes: \( 1 \) Black : \( 1 \) White.

#### Final Answer:
- Genotypes: \( 1Bb \), \( 1bb \)
- Phenotypes: \( 1 \) Black, \( 1 \) White

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Problem 25: A heterozygous round pea is crossed with a purebred round pea. Predict the genetic and phenotypic outcomes.

#### Given Information:
- Round peas are dominant over wrinkled peas.
- Genotype for round peas: \( R \) (dominant allele)
- Genotype for wrinkled peas: \( r \) (recessive allele)
- Heterozygous round pea has the genotype \( Rr \).
- Purebred round pea has the genotype \( RR \).

#### Solution:
1. Identify the parents' genotypes:
- Heterozygous round pea: \( Rr \)
- Purebred round pea: \( RR \)

2. Set up the Punnett square:
- The alleles from one parent are written along the top row.
- The alleles from the other parent are written along the left column.
- The Punnett square will look like this:

| | \( R \) | \( r \) |
|----|---------|---------|
| \( R \) | \( RR \) | \( Rr \) |

3. Determine the genotypes of the offspring:
- Possible genotypes: \( RR \), \( Rr \).
- Ratio of genotypes: \( 1RR : 1Rr \).

4. Determine the phenotypes of the offspring:
- \( RR \): Round (dominant phenotype)
- \( Rr \): Round (dominant phenotype)
- All offspring will have round peas.

#### Final Answer:
- Genotypes: \( RR \), \( Rr \)
- Phenotypes: Round (all)

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Summary of Answers:

1. Problem 22:
- Genotypes: \( 1TT \), \( 2Tt \), \( 1tt \)
- Phenotypes: \( 3 \) Tall, \( 1 \) Short

2. Problem 23:
- Genotypes: \( Pp \) (all)
- Phenotypes: Purple (all)

3. Problem 24:
- Genotypes: \( 1Bb \), \( 1bb \)
- Phenotypes: \( 1 \) Black, \( 1 \) White

4. Problem 25:
- Genotypes: \( RR \), \( Rr \)
- Phenotypes: Round (all)

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Final Boxed Answers:

\[
\boxed{
\begin{array}{l}
\text{22. Genotypes: } 1TT, 2Tt, 1tt; \text{ Phenotypes: } 3 \text{ Tall}, 1 \text{ Short} \\
\text{23. Genotypes: } Pp \text{ (all)}; \text{ Phenotypes: } \text{Purple (all)} \\
\text{24. Genotypes: } 1Bb, 1bb; \text{ Phenotypes: } 1 \text{ Black}, 1 \text{ White} \\
\text{25. Genotypes: } RR, Rr; \text{ Phenotypes: } \text{Round (all)}
\end{array}
}
\]