Which one of the following organisms is not an example of a unicellular eukaryote?

Options

A. Euglena
B. Gonyaulax
C. Amoeba
D. E. coli

Answer

To solve the question of which organism is not an example of a unicellular eukaryote, we can follow these steps:

### Step 1: Understand the Definitions
- **Unicellular Organisms**: These are organisms that consist of a single cell. They perform all necessary life functions within that one cell.
- **Eukaryotes**: These are organisms whose cells have a nucleus enclosed within membranes, along with other organelles.

### Step 2: Identify the Organisms in the Options
We need to analyze the options provided:
1. **Euglena**: A unicellular organism that belongs to the kingdom Protista. It is a eukaryote.
2. **Goniolex**: This is a type of dinoflagellate, also a unicellular eukaryote belonging to the kingdom Protista.
3. **Amoeba**: A well-known unicellular organism that is also a eukaryote and belongs to the kingdom Protista.
4. **E. coli**: This is a bacterium, which is a unicellular organism but is classified as a prokaryote, not a eukaryote.

### Step 3: Determine the Correct Answer
From the analysis:
- **Euglena**, **Goniolex**, and **Amoeba** are all unicellular eukaryotes.
- **E. coli** is a unicellular prokaryote.

Thus, the organism that is **not** an example of a unicellular eukaryote is **E. coli**.

### Final Answer
**E. coli** is not an example of a unicellular eukaryote.

---