What is the structure and function of plastids ?

Explanation

**Step-by-Step Solution:**

1. **Definition of Plastids**: Plastids are specialized organelles found in plant cells and some algae. They are essential for various cellular functions, particularly in photosynthesis and storage.

2. **Structure of Plastids**:
- Plastids are double membrane-bound organelles. This means they have an outer and an inner membrane.
- They are primarily found in plant cells, algae, and some euglenoids.

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