Final answer:
An organism with the genotype Bb for a certain trait is considered to be heterozygous. The organism has one dominant allele (B) and one recessive allele (b). The dominant allele will be expressed in the phenotype, while the recessive allele will not be observed.
Step-by-step explanation:
An organism with the genotype Bb for a certain trait is considered to be heterozygous. In genetics, the term heterozygous refers to having two different alleles for a specific gene. In this case, the organism has one dominant allele (B) and one recessive allele (b). The dominant allele (B) will be expressed in the phenotype, while the recessive allele (b) will not be observed.