Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice Test 2025 - Free Practice Questions and Study Guide

A hybrid organism is best described as having one dominant allele and one recessive allele for a specific trait. This genetic makeup arises from the combination of alleles inherited from its parents, where the dominant allele can mask the expression of the recessive allele.

For example, if we consider flower color in a plant, where purple is a dominant trait (represented by "P") and white is a recessive trait (represented by "p"), a hybrid organism would have the genotype "Pp." In this case, the purple color would be expressed due to the presence of the dominant allele, while the recessive trait remains hidden. This concept is crucial in genetics as it emphasizes the interaction between dominant and recessive alleles in defining an organism's phenotype.

Other descriptions do not align with the definition of a hybrid. Having two identical alleles indicates a homozygous organism, which is not considered a hybrid. Expressing only dominant traits suggests a homozygous dominant condition, whereas a purely recessive trait signifies the presence of two recessive alleles. Thus, the definition of a hybrid organism is most accurately captured by the presence of one dominant and one recessive allele.