Which groups of microbes consist of only unicellular organisms?

Explanation

**Step-by-Step Solution:**

1. **Understanding Microbes**: Microbes, or microorganisms, are tiny living organisms that cannot be seen with the naked eye. They require a microscope for observation, and their sizes are typically measured in microns.

2. **Identifying Unicellular Organisms**: Unicellular organisms are those that consist of a single cell. This single cell is capable of performing all the necessary life functions, such as digestion, excretion, and other metabolic processes.

3. **Groups of Microbes**: The two main groups of microbes that consist exclusively of unicellular organisms are:
- **Bacteria**: These are prokaryotic organisms, meaning they lack a well-defined nucleus and other membrane-bound organelles. Bacteria are simple in structure but can perform all life functions within a single cell.
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