In tomatoes, red fruit is dominant to yellow fruit color. A farmer has plants that produce either red or yellow tomatoes. he has signed a contract with a large seed company to provide pure red dees and pure yellow seeds. the do not want hybrids. How can the farmer determine if his red tomatoes are pure or hybrid. The farmer can't see the genotype except for one phenotype.
To determine if the red tomatoes are pure or hybrid, the farmer can perform a test cross. This involves crossing the red tomato plants with the yellow tomato plants and observing the phenotypic ratios of the offspring.
Here's how the farmer can conduct the test cross:
1. Select a red tomato plant with the desired phenotype and collect its pollen.
2. Identify a yellow tomato plant as the cross partner. Ensure that it is pure for the yellow trait and does not carry the red allele.
3. Transfer the pollen from the red tomato plant to the stigma of the yellow tomato plant. This can be done by gently rubbing the anthers of the red flower onto the stigma of the yellow flower.
4. Allow the flowers to naturally form fruits and let them mature.
5. Once the fruits are ripe, observe and record their colors. Remember that red is dominant over yellow.
6. Count and record the number of red and yellow tomatoes obtained from the test cross.
Interpreting the Results:
- If all the fruits from the test cross are red, it indicates that the red tomato plant used in the cross is pure for the red trait.
- If all the fruits from the test cross are yellow, it suggests that the red tomato plant used in the cross is a hybrid.
- If the fruits from the test cross are a mix of red and yellow, it implies that the red tomato plant used in the cross is a hybrid.
By performing this test cross and analyzing the resulting offspring, the farmer can determine whether the red tomatoes are pure or hybrid.