Question 10

The result of this cross was best explained by codominance.

The pink flowers produced from the cross-pollination of a red flower (RR) and a white flower (WW) illustrate the concept of codominance, where both alleles in a heterozygous genotype are fully expressed.

A) non-disjunction

Non-disjunction refers to the failure of homologous chromosomes to separate properly during cell division, leading to gametes with an abnormal number of chromosomes. This genetic phenomenon does not explain the mixing of flower colors seen in the pink flowers, as it pertains to chromosome number rather than allele expression.

B) multiple alleles

Multiple alleles refer to the presence of more than two alleles for a gene within a population. While this concept is important in genetics, it does not apply to this scenario since only two alleles (R and W) are involved in the inheritance of flower color. Thus, it does not explain the pink flower outcome.

C) mutation

A mutation involves a change in the DNA sequence of a gene, which can lead to new traits. However, the pink flower phenotype is not a result of a mutation in the genetic code but rather a straightforward expression of the existing alleles, making this option irrelevant to the observed flower colors.

D) codominance

Codominance is a genetic scenario where both alleles are equally expressed in the phenotype of the heterozygote. In this case, the presence of both red (R) and white (W) alleles in the RW genotype results in the pink color, demonstrating that each allele contributes to the phenotype without one overshadowing the other.

Conclusion

Codominance is the definitive explanation for the pink flowers resulting from the cross of a red and a white flower, as it highlights the equal expression of both alleles. Other options, such as non-disjunction, multiple alleles, and mutation, do not align with the observed flower coloration and fail to account for the genetic mechanism at play in this instance.