Final answer:
The offspring of a cross between two heterozygous tall plants will exhibit a 3:1 phenotypic ratio of tall to short plants, as predicted by Mendelian genetics and confirmed through a Punnett square analysis.
Step-by-step explanation:
Predicting Offspring Ratios in Genetic Crosses:
When two plants, both heterozygous for height, are crossed, we can predict the offspring's phenotype ratios using a Punnett square. Heterozygous means having one dominant and one recessive allele for a trait. If we assume height in pea plants follows Mendelian genetics, with 'T' being the dominant tall allele and 't' being the recessive short allele, a heterozygous plant would have the genotype 'Tt'.
Using a Punnett square, the cross of two Tt plants would produce the following genotypes: TT, Tt, Tt, and tt. This results in a phenotypic ratio of 3 tall plants to 1 short plant because the 'T' allele is dominant and will express the tall phenotype both in the TT and Tt genotypes. The tt genotype will express the short phenotype as it lacks the dominant allele.
Thus, when conducting a cross between two tall pea plants that are heterozygous for height, one can expect the offspring to show a 3:1 ratio of tall to short plants.