Final answer:
The genotype Bb in pea plants indicates a heterozygous individual with one dominant and one recessive allele, expressing the dominant purple flower phenotype.
Step-by-step explanation:
The genotype Bb of a pea plant describes an individual that is heterozygous for a particular trait. This means that the pea plant has two different alleles for the gene in question: one dominant allele (B) and one recessive allele (b). In the context of pea plant flower color, purple flowers (B) are dominant over white flowers (b). Therefore, a plant with the genotype Bb would express the dominant purple flower phenotype. When crossing two heterozygous Bb pea plants, you can expect a 3:1 ratio of purple to white flowers in the offspring as per Mendelian genetics. A Punnett square analysis can be used to predict such genetic crosses and probabilities of genotypes and phenotypes in the offspring.