Final answer:
The wild type Drosophila fruit fly has antennae on its head, while a mutation in the regulatory DNA causing ectopic expression of the Antennapedia gene results in legs growing on the head instead of antennae.
Step-by-step explanation:
In Drosophila fruit flies, the wild type refers to the normal, natural form of the organism. In this case, the wild-type Drosophila has antennae on its head, which is the typical characteristic.
On the other hand, ectopic expression of the Antennapedia gene in the head due to a mutation in its regulatory DNA leads to a mutant form of the fruit fly. In this mutant, legs grow on the head in place of antennae. This occurs because the mutation expands the distribution of the Antennapedia gene product, causing legs to develop where antennae should be.
In Drosophila fruit flies, the wild type represents the natural, standard form of the organism, characterized by having antennae on the head. Conversely, the ectopic expression of the Antennapedia gene, resulting from a mutation in its regulatory DNA, gives rise to a mutant phenotype. In this aberrant form, legs develop on the head instead of antennae. The mutation disrupts the normal regulatory control of the Antennapedia gene, causing its product to be distributed inappropriately.
This misexpression leads to the transformation of antennae into leg structures, exemplifying the critical role of gene regulation in determining the proper development and morphology of body parts in organisms like Drosophila.