Final answer:
The life cycle variation known as alternation of generations, which includes both haploid and diploid stages and is typical in plant life cycles, is no longer considered abnormal.
Step-by-step explanation:
One variation in the life cycle that can no longer be considered abnormal is alternation of generations. This biological concept is especially prevalent in plants, where there are both haploid and diploid stages. In the alternation of generations, an organism alternates between multicellular haploid and diploid forms. This cycle adds complexity beyond the more linear haploid life cycle, where organisms spend most of their lives as haploid cells, and the diploid life cycle, where diploidy predominates until gamete formation.
The alternation of generations is a clear departure from the concept of a singular 'final' form in development, instead presenting a lifecycle with multiple, repeating stages exhibiting unique organismal forms.