Final answer:
A cross between a homozygous tall pea plant (TT) and a homozygous short pea plant (tt) yields offspring that are all heterozygous (Tt) and display the tall phenotype due to the dominant tall allele.
Step-by-step explanation:
Understanding Genetic Crosses and Predicting Offspring Ratios
When you cross a tall pea plant (TT) with a short pea plant (tt), you are performing a classic Mendelian genetic cross involving dominant and recessive traits. Since the tall trait is dominant (represented as 'T'), and the short trait is recessive (represented as 't'), a cross between a homozygous tall pea plant (TT) and a homozygous short pea plant (tt) will result in offspring that all have the genotype Tt. These offspring will show the phenotype of being tall, as the dominant allele (T) masks the expression of the recessive allele (t).
In a theoretical cross using a Punnett square, you can predict the offspring genotype and phenotype ratios. If you were to cross a heterozygous tall pea plant (Tt) with another heterozygous tall pea plant (Tt), you would see a genotypic ratio of 1 TT : 2 Tt : 1 tt, and a corresponding phenotypic ratio of 3 tall to 1 short. This is because the alleles segregate during gamete formation, and each parent has an equal chance of passing down either one of their alleles.