Question

d. in tomatoes, red fruit (r) is dominant to yellow fruit (r). cross a homozygous recessive fruit with a heterozygous fruit. answer the questions that follow.

1. how many possible genotypes are there among the offspring?
2. how many possible phenotypes are there among the offspring?
3. what percentage of the offspring ar red?
4. what percentage of the offspring c yellow?
5. what is the phenotypic ratio of the offspring?
6. what is the genotypic ratio of the offspring?

Explanation:

Step1: Determine the genotypes of the parents

The homozygous recessive fruit has the genotype \( rr \). The heterozygous fruit has the genotype \( Rr \).

Step2: Set up the Punnett square

The gametes of \( rr \) are \( r \) and \( r \). The gametes of \( Rr \) are \( R \) and \( r \).

$$\begin{array}{|c|c|c|} \hline & R & r \\ \hline r & Rr & rr \\ \hline r & Rr & rr \\ \hline \end{array}$$

Step3: Analyze genotypes

From the Punnett square, the genotypes are \( Rr \) and \( rr \). So, there are \( 2 \) possible genotypes.

Step4: Analyze phenotypes

Since \( R \) (red) is dominant, \( Rr \) is red and \( rr \) is yellow. So, there are \( 2 \) possible phenotypes.

Step5: Calculate percentage of red - fruit offspring

Out of \( 4 \) offspring in the Punnett square, \( 2 \) are \( Rr \) (red). The percentage is \(\frac{2}{4}\times100\% = 50\%\).

Step6: Calculate percentage of yellow - fruit offspring

Out of \( 4 \) offspring, \( 2 \) are \( rr \) (yellow). The percentage is \(\frac{2}{4}\times100\% = 50\%\).

Step7: Determine phenotypic ratio

The number of red - fruit offspring (\( Rr \)) is \( 2 \), and the number of yellow - fruit offspring (\( rr \)) is \( 2 \). The phenotypic ratio is \( 1:1\) (red : yellow).

Step8: Determine genotypic ratio

The number of \( Rr \) is \( 2 \), and the number of \( rr \) is \( 2 \). The genotypic ratio is \( 1:1\) (\( Rr:rr \)).

Answer:

1. \( 2 \)
2. \( 2 \)
3. \( 50\%\)
4. \( 50\%\)
5. \( 1:1\) (red : yellow)
6. \( 1:1\) (\( Rr:rr \))