Why is cell called 'the structural and functional unit of life'?

Explanation

**Step-by-Step Solution:**

1. **Definition of a Cell**: A cell is the smallest unit of life that can function independently and perform all necessary life processes.

2. **Composition of Organisms**: All living organisms, whether unicellular (like bacteria) or multicellular (like plants and animals), are made up of cells. In multicellular organisms, cells group together to form tissues, which then form organs, and ultimately organ systems.

3. **Functionality of Cells**: Each cell is capable of carrying out essential life functions such as metabolism, respiration, excretion, and reproduction. This means that even a single cell can sustain life on its own.

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