A red-flowered rose is crossed with a white-flowered rose. All of their offspring are pink. This is an example of
A sex-linked genetics.
B monohybrid genetics.
C incomplete dominance.
The correct answer and explanation is:
The correct answer is C: incomplete dominance.
In incomplete dominance, neither allele is completely dominant over the other, leading to a blending of traits in the offspring. This phenomenon occurs when the heterozygous phenotype is an intermediate between the two homozygous phenotypes.
In this case, when a red-flowered rose is crossed with a white-flowered rose, the offspring show a pink color, which is a mix of the red and white traits. This blending is characteristic of incomplete dominance, where the heterozygous individual exhibits a phenotype that is distinct from both the homozygous parent traits.
To further explain, consider the alleles for flower color in roses. Let’s say the allele for red color is represented by R, and the allele for white color is represented by W. When the red-flowered rose (genotype RR) is crossed with the white-flowered rose (genotype WW), all offspring inherit one allele from each parent, resulting in the genotype RW. Since neither the red nor white allele is fully dominant, the resulting phenotype is a blend of the two colors, which is pink.
This is different from complete dominance, where one allele completely masks the expression of the other, and also from codominance, where both alleles are fully expressed in the heterozygous condition (such as with AB blood type). In incomplete dominance, the heterozygous phenotype is a mixture or intermediate of the two parental traits, as demonstrated by the pink flowers.