What is a characteristic of eukaryotic organisms?

Eukaryotic organisms are defined by their complex cellular structures, which include the presence of membrane-bound organelles. These organelles, such as the nucleus, endoplasmic reticulum, and mitochondria, allow for compartmentalization of various cellular processes, leading to greater efficiency and specialization. This structural complexity is one of the key characteristics that distinguishes eukaryotes from prokaryotic organisms, which lack these membrane-bound organelles.

In contrast, the other options do not accurately represent eukaryotic organisms. For instance, not having a nucleus is a defining feature of prokaryotes, meaning that eukaryotes are, by definition, organisms that do possess a nucleus. The statement that eukaryotes reproduce only asexually is misleading, as many eukaryotes can reproduce sexually as well. Finally, while some eukaryotic organisms are unicellular, such as yeast and certain protozoa, many, including plants, animals, and fungi, are multicellular. Thus, the characteristic of possessing membrane-bound organelles stands out as a key feature of eukaryotic life forms.