Cell theory states that cells are structural and fundamental units of _________

Options

A. plants
B. animals
C. both plants and animals
D. only microorganisms

Answer

**Step-by-Step Solution:**

1. **Understanding Cell Theory**: The first step is to recognize what cell theory states. It emphasizes that cells are the basic structural and functional units of all living organisms.

2. **Historical Background**: The cell theory was developed in the 19th century by scientists. In 1838, Matthias Schleiden proposed that all plants are made of cells, indicating that cells are the structural and functional units of plants.

3. **Contribution of Schwann**: In 1839, Theodor Schwann extended this idea to animals, stating that all animals are also made up of cells. This means that cells serve as the fundamental units for both plants and animals.

4. **Unified Cell Theory**: The combination of Schleiden's and Schwann's findings led to the unified cell theory, which states that all living organisms, whether they are plants, animals, or microorganisms, are composed of cells.

5. **Conclusion**: Therefore, according to cell theory, cells are the structural and fundamental units of all living organisms, which includes plants, animals, and microorganisms.

**Final Answer**: Cells are structural and fundamental units of **all living organisms**.

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