GED Science TestLife ScienceEasy
A scientist is studying a newly discovered single-celled organism. Microscopic examination reveals that the organism lacks a membrane-bound nucleus and other membrane-bound organelles. Its genetic material is located in a nucleoid region. Based on these characteristics, how would this organism be classified?
- AAs a eukaryotic cell
- BAs a prokaryotic cell
- CAs a virus
- DAs a plant cell
Show answer & explanationAnswer & explanation
Correct answer: B. As a prokaryotic cell
The defining characteristics of a prokaryotic cell are the absence of a membrane-bound nucleus and other membrane-bound organelles, with genetic material located in a nucleoid region. These features distinguish prokaryotes from eukaryotes.
Why the other options are wrong
- A. Eukaryotic cells possess a membrane-bound nucleus and other membrane-bound organelles.
- C. Viruses are non-cellular infectious agents, not cells, and lack the cellular structures described.
- D. Plant cells are a type of eukaryotic cell and thus have a membrane-bound nucleus and organelles.
Prokaryotic Cell Characteristics
Prokaryotic cells are the simplest and most ancient forms of life. They are characterized by the absence of a membrane-bound nucleus and other membrane-bound organelles.
- Lack a true nucleus; genetic material in nucleoid region.
- Do not have membrane-bound organelles (e.g., mitochondria, ER).
- Typically single-celled organisms (bacteria, archaea).
- Smaller and simpler in structure than eukaryotic cells.
Memory trick: Pro-no nucleus, Eu-do nucleus!