Question

In a given hybridization between two flowers, red "R" is dominant, and white "r" is recessive. In a cross between two white-flowered plants, what statement would BEST describe the offspring? A) 75% of the flowers would be white and the remaining 25% would be red. B) There would be some variation; most flowers would be white and a few would be red. C) There would be no variation in color. All flowers will be white unless a mutation occurred. D) Flower color variation would be equally divided given the homozygous parents: half red and half white.

Answer 1

C, since rr and rr together cannot make Rr or RR.

Answer 2

Answer:

C) There would be no variation in color. All flowers will be white unless a mutation occurred.

Explanation:

A recessive phenotype is generated in an offspring when the offspring receives both the recessive alleles for a trait from each of its parent. So if a progeny has white phenotype then it simply means that it does not have any dominant allele because dominant allele masks the expression of recessive allele and produces a dominant phenotype. Here, red "R" is dominant while  white "r" is recessive.

The Punnett square diagram for a cross between two white-flowered plants is attached.

It is clear from the diagram that all the progeny will have recessive "rr" genotype so all of them will have white flowers.

But, in case a mutation occurs in those plants which changes the recessive allele (r) to dominant (R) or any other variant allele then only some variations in flower color  may occur.