Question

If a true-breeding blue-flowered plant was crossed with a true-breeding white-flowered plant, what phenotypic ratio would we observe in the progeny resulting from this cross? Assume the white-flowered trait is completely dominant.A. 100 percent blueB. 100 percent whiteC. 75 percent blue, 25 percent whiteD. 100 percent light blueE. Not enough information is provided to answer this question.

Answer 1

Answer:

B. 100 percent white

Explanation:

According to Mendel's law of dominance, the dominant allele of a gene masks the expression of the recessive allele in a heterozygous state. Therefore, when two pure breeding plants that differ with respect to one genetic trait are crossed, the progeny expresses only the dominant phenotype. Here, one allele should be completely dominant over the other. The allele for the white flowers is completely dominant over the allele for the blue flowers.

Let' assume that the allele "W" imparts white color to the flowers while the allele "w" gives blue color. When a true-breeding blue-flowered plant (ww) is crossed with a true-breeding white-flowered plant (WW), the progeny would be heterozygous for the dominant allele "W" and would exhibit "white color of flowers" (the dominant trait).

WW (white-flowered plant) x ww (blue-flowered plant) = Ww (white-flowered plant)