Final answer:
In the case of a flower species with a gene for petal color that exhibits incomplete dominance, the heterozygous condition results in an intermediate petal color. This is exemplified by snapdragons, where heterozygous offspring have pink petals, which is a blend of red and white from the parent alleles.The correct option is b
Step-by-step explanation:
When discussing a gene for petal color that has one dominant and one recessive allele, the heterozygous condition often produces an intermediate phenotype due to a form of inheritance known as incomplete dominance. Taking the example of snapdragon flowers (Antirrhinum majus), a cross between a red-flowered plant (RR) and a white-flowered plant (WW) will yield progeny with a mix of the two colors, resulting in pink flowers (RW). This happens because neither allele is fully dominant over the other, and so both contribute to the flower's color in the heterozygote.
This is different from codominance, where both alleles would be fully expressed and visible, an example of which could be a flower with both red and white petals. An example of simple or complete dominance would be a pea plant with flower color, where the presence of one purple allele (P) completely dominates the white allele (p), resulting in a purple flower even in the heterozygous state (Pp). In the given scenario of intermediate petal color, we see a blending of traits that contradicts classic Mendelian inheritance, which would dictate that only one allele's trait would be visible in the phenotype.
Learn more about Incomplete Dominance