Completed dihybrid cross worksheet with red ink annotations and solutions.

Problem Analysis and Solution

The worksheet involves dihybrid crosses, which are genetic crosses involving two traits. We will solve the problems step by step, using Punnett squares to determine probabilities and possible genotypes.

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#### Part 1: Plant Height and Flower Color

##### Step 1: Set up the Punnett Square
- Dominant allele for tall plants: \( D \)
- Recessive allele for dwarf plants: \( d \)
- Dominant allele for purple flowers: \( W \)
- Recessive allele for white flowers: \( w \)
- Cross: Homozygous dominant parent (\( DDWW \)) with a homozygous recessive parent (\( ddww \))

The gametes from the parents are:
- Parent 1 (\( DDWW \)): \( DW \)
- Parent 2 (\( ddww \)): \( dw \)

The Punnett square is set up as follows:

| | \( DW \) | \( DW \) | \( DW \) | \( DW \) |
|-------|----------|----------|----------|----------|
| \( dw \) | \( DdWw \) | \( DdWw \) | \( DdWw \) | \( DdWw \) |
| \( dw \) | \( DdWw \) | \( DdWw \) | \( DdWw \) | \( DdWw \) |
| \( dw \) | \( DdWw \) | \( DdWw \) | \( DdWw \) | \( DdWw \) |
| \( dw \) | \( DdWw \) | \( DdWw \) | \( DdWw \) | \( DdWw \) |

All offspring have the genotype \( DdWw \).

##### Step 2: Answer the Questions
1. Probability of producing tall plants with purple flowers?
- All offspring have the genotype \( DdWw \), which results in tall plants with purple flowers.
- Probability: \( 100\% \) or \( 16/16 \)
- Possible genotypes: \( DdWw \)

2. Probability of producing dwarf plants with white flowers?
- No offspring can have the genotype \( ddww \) because one parent is homozygous dominant for both traits.
- Probability: \( 0\% \) or \( 0/16 \)
- Possible genotypes: None (only \( DdWw \) is possible)

3. Probability of producing tall plants with white flowers?
- No offspring can have the genotype \( DDww \) or \( Ddww \) because one parent is homozygous dominant for flower color.
- Probability: \( 0\% \) or \( 0/16 \)
- Possible genotypes: None (only \( DdWw \) is possible)

4. Probability of producing dwarf plants with purple flowers?
- No offspring can have the genotype \( ddWW \) or \( ddWw \) because one parent is homozygous recessive for plant height.
- Probability: \( 0\% \) or \( 0/16 \)
- Possible genotypes: None (only \( DdWw \) is possible)

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#### Part 2: Guinea Pig Fur Color and Texture

##### Step 1: Set up the Punnett Square
- Dominant allele for black fur: \( B \)
- Recessive allele for white fur: \( b \)
- Dominant allele for rough fur: \( R \)
- Recessive allele for smooth fur: \( r \)
- Cross: Heterozygous parent (\( BbRr \)) with a heterozygous parent (\( BbRr \))

The gametes from each parent are:
- Parent 1 (\( BbRr \)): \( BR, Br, bR, br \)
- Parent 2 (\( BbRr \)): \( BR, Br, bR, br \)

The Punnett square is set up as follows:

| | \( BR \) | \( Br \) | \( bR \) | \( br \) |
|-------|----------|----------|----------|----------|
| \( BR \) | \( BBRR \) | \( BBRr \) | \( BbRR \) | \( BbRr \) |
| \( Br \) | \( BBRr \) | \( BBrr \) | \( BbRr \) | \( Bbrr \) |
| \( bR \) | \( BbRR \) | \( BbRr \) | \( bbRR \) | \( bbRr \) |
| \( br \) | \( BbRr \) | \( Bbrr \) | \( bbRr \) | \( bbrr \) |

##### Step 2: Answer the Questions
1. Probability of producing guinea pigs with black, rough fur?
- Offspring with black fur must have at least one \( B \) allele.
- Offspring with rough fur must have at least one \( R \) allele.
- Genotypes: \( BBRR, BBRr, BbRR, BbRr \)
- Count the number of these genotypes in the Punnett square: 9 out of 16
- Probability: \( 9/16 \)
- Possible genotypes: \( BBRR, BBRr, BbRR, BbRr \)

2. Probability of producing guinea pigs with black, smooth fur?
- Offspring with black fur must have at least one \( B \) allele.
- Offspring with smooth fur must have the genotype \( rr \).
- Genotypes: \( BBrr, Bbrr \)
- Count the number of these genotypes in the Punnett square: 3 out of 16
- Probability: \( 3/16 \)
- Possible genotypes: \( BBrr, Bbrr \)

3. Probability of producing guinea pigs with white, rough fur?
- Offspring with white fur must have the genotype \( bb \).
- Offspring with rough fur must have at least one \( R \) allele.
- Genotypes: \( bbRR, bbRr \)
- Count the number of these genotypes in the Punnett square: 3 out of 16
- Probability: \( 3/16 \)
- Possible genotypes: \( bbRR, bbRr \)

4. Probability of producing guinea pigs with white, smooth fur?
- Offspring with white fur must have the genotype \( bb \).
- Offspring with smooth fur must have the genotype \( rr \).
- Genotype: \( bbrr \)
- Count the number of these genotypes in the Punnett square: 1 out of 16
- Probability: \( 1/16 \)
- Possible genotypes: \( bbrr \)

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Final Answers

#### Part 1: Plant Height and Flower Color
1. Probability of producing tall plants with purple flowers?
\(\boxed{100\%}\)
Possible genotypes: \( DdWw \)

2. Probability of producing dwarf plants with white flowers?
\(\boxed{0\%}\)
Possible genotypes: None

3. Probability of producing tall plants with white flowers?
\(\boxed{0\%}\)
Possible genotypes: None

4. Probability of producing dwarf plants with purple flowers?
\(\boxed{0\%}\)
Possible genotypes: None

#### Part 2: Guinea Pig Fur Color and Texture
1. Probability of producing guinea pigs with black, rough fur?
\(\boxed{9/16}\)
Possible genotypes: \( BBRR, BBRr, BbRR, BbRr \)

2. Probability of producing guinea pigs with black, smooth fur?
\(\boxed{3/16}\)
Possible genotypes: \( BBrr, Bbrr \)

3. Probability of producing guinea pigs with white, rough fur?
\(\boxed{3/16}\)
Possible genotypes: \( bbRR, bbRr \)

4. Probability of producing guinea pigs with white, smooth fur?
\(\boxed{1/16}\)
Possible genotypes: \( bbrr \)