In a cross of a round hybrid pea with a true breeding round parent (Ww x WW), what genotypic proportions would be observed in the offspring?
A. All round
B. Half heterozygous, half homozygous dominant
C. All heterozygous
D. Half round, half wrinkled
To determine the genotypic proportions in the offspring of a cross between a round hybrid pea (Ww) and a true-breeding round parent (WW), we need to consider the principles of Mendelian genetics.
In this cross, the round hybrid pea has one dominant allele (W) and one recessive allele (w) for the shape of the peas. The true-breeding round parent has two dominant alleles (WW) for the shape.
When we perform a cross between Ww and WW, there are two possible genotypes for the offspring: Ww and WW. The dominant allele (W) is always expressed over the recessive allele (w), so both genotypes will result in round peas.
Therefore, the correct answer is A. All round.