Question

suppose a true-breeding blue flower is crossed with a true-breeding yellow flower. in the next generation, all of the flowers are blue. what does this outcome tell you about the allele for blue flowers? \bigcirc the blue allele is sex-linked. \bigcirc the blue allele shows incomplete dominance. \bigcirc the blue allele is dominant to the yellow allele. \bigcirc the blue allele is recessive to the yellow allele.

Explanation:

1. Analyze the first option: Sex - linked alleles are related to the sex chromosomes and affect traits based on the sex of the organism. Since the problem is about flower color (flowers don't have sex chromosomes in the same way as animals with sex - linked inheritance), this option is incorrect.
2. Analyze the second option: In incomplete dominance, the heterozygous phenotype is an intermediate between the two homozygous phenotypes. For example, if red and white flowers show incomplete dominance, the offspring would be pink. But in this case, all offspring are blue, not an intermediate, so this option is incorrect.
3. Analyze the third option: When a true - breeding blue flower (homozygous for the blue allele) is crossed with a true - breeding yellow flower (homozygous for the yellow allele), and all the offspring are blue, it means that the blue allele masks the expression of the yellow allele. By definition, a dominant allele is one that is expressed in the heterozygous condition and masks the recessive allele. So the blue allele is dominant over the yellow allele.
4. Analyze the fourth option: If the blue allele were recessive to the yellow allele, the offspring (which would be heterozygous) would show the yellow phenotype, not the blue phenotype. So this option is incorrect.

Answer:

The blue allele is dominant to the yellow allele.