Red roses are dominant to white roses and tall are dominant to short. cross a flower that is homozygous red and tall with a flower that is white and heterozygous tall

All Offsprings will have a red flower and tall phenotype with a genotypic ratio of 1 RrTT : 1 RrTt

Explanation:

This is a cross involving two genes; one coding for rose color and the other for height in rose plant. The red allele (R) is dominant over the white allele (r) in the first gene while tallness (T) is dominant over shortness (t) in the second gene.

Based on this, a homozygous red and tall flower will possess a genotype: RRTT while a flower that is white and heterozygous tall will have genotype: rrTt. Hence, each parent's allele will separate into gametes independently of one another according to Mendel's law of independent assortment. The possible gametes combination are:

RRTT- RT, RT, RT, RT

rrTt- rT, rt, rT, rt.

Hence, using a punnet square (see attached image), all offsprings will possess the phenotypic dominant trait i.e. red and tall. The genotypes produced are: RrTT and RrTt in a ratio 1:1