Which is a characteristic of something in the domain bacteria
A) membrane-enclosed organelles
B) cell nucleus
C) multicellular
D) unicellular
The Correct Answer and Explanation is :
The correct answer is D) unicellular.
Explanation:
Bacteria are unicellular organisms, meaning they are made up of a single cell. This is one of the key characteristics that distinguish them from multicellular organisms like plants and animals, which are made up of many cells. Bacteria do not have the complex cellular structure seen in eukaryotic cells, which include membrane-enclosed organelles such as the nucleus and mitochondria.
- Lack of membrane-enclosed organelles (A): Unlike eukaryotes (such as animal and plant cells), bacteria do not have membrane-bound organelles. For example, they do not have a true nucleus to house their genetic material. Instead, the DNA in bacteria is found in a region called the nucleoid, which is not enclosed by a membrane. Bacteria also lack organelles like mitochondria and chloroplasts, which are common in eukaryotic cells.
- No cell nucleus (B): As noted, bacteria lack a nucleus—the defining feature of eukaryotic cells. In eukaryotes, the nucleus encloses the cell’s genetic material, but in bacteria, the genetic material is not enclosed by a membrane. Instead, it is free-floating within the cell in the form of a single, circular chromosome.
- Unicellular (D): Bacteria are single-celled organisms. This unicellularity allows them to perform all of the necessary life functions (growth, reproduction, metabolism) within a single cell. While bacteria can form colonies, each bacterium is an individual cell.
- Multicellular (C): Bacteria are not multicellular organisms. Multicellular organisms consist of many specialized cells working together, whereas bacteria are simpler, single-celled organisms. Even though certain bacteria can form clusters or chains, they are still unicellular organisms.
In summary, bacteria are unicellular organisms that lack a nucleus and membrane-bound organelles, making them significantly different from more complex eukaryotic cells.