Question

In maize, the dominant allele b-i encodes a transcription factor that regulates genes producing purple color in corn stalks and husks. The allele can mutate to b', changing the color to green. In a cross between b-i b-i and b' b' homozygotes, the F1 heterozygotes all have green stalks and husks. This shows that the b' allele is:

a) More stable than the b-i allele.
b) Incomplete dominant.
c) Recessive.
d) Dominant.

Answer 1

In maize, the green color observed in the F1 heterozygotes from a cross between b-i b-i and b' b' homozygotes indicates that the b' allele is d) dominant over the b-i allele.

Step-by-step explanation:

In maize, the dominant allele b-i encodes a transcription factor that is responsible for producing the purple color seen in corn stalks and husks. A mutation of this allele, b', results in a green color.

When individuals that are homozygous for the b-i allele (b-i b-i) are crossed with individuals homozygous for the b' allele (b' b'), all the F1 offspring exhibit green stalks and husks. This phenotype in the F1 heterozygotes demonstrates that the b' allele is dominant over the b-i allele.

Observing Mendelian inheritance, when a cross between two homozygous individuals gives rise to offspring with one phenotype, it indicates that the allele associated with that phenotype is dominant. Thus, considering the information and the example provided, the correct option for the outcome of the cross is that the b' allele is dominant.