What are we referring to when we say 'simple organisms' or 'complex organisms'?

Explanation

### Step-by-Step Solution:

1. **Definition of Simple Organisms**:
- Simple organisms are those that possess a basic structure and functional organization. They are often referred to as primitive organisms. Examples include unicellular organisms like bacteria and some protists.

2. **Characteristics of Simple Organisms**:
- Simple organisms typically have fewer specialized cells and systems. Their body organization is less complex, which allows them to perform essential life processes with minimal structural requirements.

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