In a specific scenario, red flowers are dominant over white flowers. A plant heterozygous for red flowers and a plant with white flowers are crossed. What is the expected proportion of phenotypes in the next generation?

Rationale

In the next generation, the expected proportion of phenotypes will be 2 red flowers and 2 white flowers.

In this genetic cross, the heterozygous red flower plant (Rr) is crossed with a homozygous white flower plant (rr). The resulting offspring will display a 50% ratio of red to white flowers in their phenotypes, leading to an expected proportion of 2 red flowers and 2 white flowers in a total of 4 offspring.

A (2 red, 2 white) CORRECT

This choice accurately reflects the expected phenotype ratio from the cross between a heterozygous red flower plant (Rr) and a homozygous white flower plant (rr). The offspring genotypes will be 50% Rr (red) and 50% rr (white), resulting in a 2:2 ratio of red to white flowers.

B (3 red, 1 white) YOUR ANSWER

This option suggests a 3:1 ratio, which is typical for a cross between two heterozygous plants (Rr x Rr). However, since one parent is homozygous recessive (rr), this ratio does not apply here, making this option incorrect for the given cross.

C (4 red, 0 white) YOUR ANSWER

This choice implies that all offspring would exhibit the dominant red phenotype. This outcome would only occur if both parents were homozygous dominant (RR), which is not the case in this scenario. Therefore, this choice is incorrect.

D (1 red, 3 white) YOUR ANSWER

This option suggests a 1:3 ratio, which is also incorrect for this cross. This ratio would be seen in a scenario where both parents were heterozygous, leading to a different set of offspring ratios. Thus, this option does not reflect the genetic outcome of the specific plants being crossed.

Conclusion

In the genetic cross between a heterozygous red flower plant and a homozygous white flower plant, the expected phenotype ratio is 2 red flowers to 2 white flowers, equating to a 1:1 ratio. This result stems from the inheritance patterns of dominant and recessive traits, confirming that the presence of one dominant allele (R) leads to the red phenotype while two recessive alleles (rr) yield the white phenotype.

In a specific scenario, red flowers are dominant over white flowers. A plant heterozygous for red flowers and a plant with white flowers are crossed. What is the expected proportion of phenotypes in the next generation?

In the next generation, the expected proportion of phenotypes will be 2 red flowers and 2 white flowers.

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