Biology STAAR Practice Test 2025 – Complete Exam Prep

The correct answer identifies prokaryotic cells, which are characterized by their lack of a true nucleus. In these cells, the genetic material, which is typically a single circular strand of DNA, is located in a region called the nucleoid rather than enclosed within a membrane-bound nucleus. This fundamental difference distinguishes prokaryotic cells from eukaryotic cells, which do contain a nucleus that houses their genetic material in a more complex, organized structure.

Understanding this distinction is critical because it highlights the cellular organization that underpins biological diversity. In addition, most prokaryotes are unicellular organisms, such as bacteria and archaea, which thrive in various environments and often play essential roles in ecosystems. The presence of a nucleus in eukaryotic cells, on the other hand, allows for greater complexity and specialization, leading to the formation of multicellular organisms. These structural differences are foundational concepts in cell biology and contribute to the classification of living organisms.