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

Explanation

**Step-by-Step Text Solution:**

1. **Understanding the Terms:**
- When we refer to 'simple organisms', we are typically talking about organisms that are primitive in nature. These organisms have not evolved complex structures or functions and are often the earliest forms of life.

2. **Characteristics of Simple Organisms:**
- Simple organisms usually exhibit a simple structure. This means they have less specialized cells and tissues. Examples include unicellular organisms like bacteria and some protists.
- Their functional organization is also straightforward, meaning that their biological processes are less complex compared to those of more advanced organisms.
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