Which of the following organelles is bounded by a double membrane?

Options

A. Lysosome
B. Nucleolus
C. Ribosome
D. Plastid

Explanation

To determine which organelle is bounded by a double membrane, we will analyze each option provided: Lysosome, Nucleolus, Ribosome, and Plastids.

### Step-by-Step Solution:

1. **Analyze Lysosome**:
- Lysosomes are known as the "suicidal bags" of the cell because they contain hydrolytic enzymes that digest cellular components.
- They are surrounded by a **single membrane**. This membrane is crucial because if it breaks, the enzymes can leak into the cytoplasm, leading to cell death.
- **Conclusion**: Lysosome is **not** bounded by a double membrane.

**Hint**: Remember that lysosomes are single-membraned organelles that contain digestive enzymes.

2. **Analyze Nucleolus**:
- The nucleolus is a dense structure found within the nucleus of the cell.
- It is involved in the synthesis of ribosomal RNA and is also surrounded by a **single membrane**.
- **Conclusion**: Nucleolus is **not** bounded by a double membrane.

**Hint**: The nucleolus is located inside the nucleus and is single-membraned.

3. **Analyze Ribosome**:
- Ribosomes are the sites of protein synthesis in the cell.
- They are not membrane-bound organelles; instead, they can be found freely in the cytoplasm or attached to the rough endoplasmic reticulum.
- **Conclusion**: Ribosomes are **not** bounded by a double membrane.

**Hint**: Ribosomes are the protein factories of the cell and do not have a membrane.

4. **Analyze Plastids**:
- Plastids are organelles found in plant cells and are involved in the synthesis and storage of food.
- There are three types of plastids: chloroplasts, chromoplasts, and leukoplasts.
- Plastids are characterized by having a **double membrane**: an outer membrane and an inner membrane.
- **Conclusion**: Plastids are indeed bounded by a double membrane.

**Hint**: Plastids are unique to plant cells and have two membranes surrounding them.

### Final Answer:
The organelle that is bounded by a double membrane is **Plastids**.