Which of the following represents a unique characteristic of many animals that, in general, distinguishes them from the members of other kingdoms?
many animals have cells with rigid cell walls.
many animals include both aquatic and terrestrial species.
many animals have organs but no tissues.
many animals have sensory organs concentrated at one end of their body.

Transposon can cause mutations in genes at or near the site of transposon insertion. it is possible for these elements to transpose away from their original site, causing a reversion of the mutant phenotype. in some cases, however, even more severe phenotypes appear when these elements excise from this site, due to events at or near the mutant allele. what might be happening to the transposon or the nearby gene to create more severe mutations?