In the fluid mosaic membrane model, the phospholipid bilayer :

Options

A. is sandwiched between two protein layers
B. is covered by a single protein layer
C. has proteins embedded in it
D. lies on top of a single protein layer

Explanation

**Step-by-Step Solution:**

1. **Understanding the Fluid Mosaic Model**: The fluid mosaic model describes the structure of cell membranes. It emphasizes that the membrane is not a rigid structure but rather a fluid combination of lipids and proteins.

2. **Phospholipid Bilayer**: The fundamental component of the cell membrane is the phospholipid bilayer. This bilayer consists of two layers of phospholipids, where the hydrophilic (water-attracting) heads face outward towards the aqueous environment, and the hydrophobic (water-repelling) tails face inward, away from water.

3. **Movement of the Bilayer**: The term "fluid" in the fluid mosaic model indicates that the phospholipids and proteins can move laterally within the layer, allowing for flexibility and the ability to self-heal.

4. **Proteins in the Membrane**: The "mosaic" aspect refers to the various proteins that are embedded within the phospholipid bilayer. These proteins can be classified into two categories:
- **Integral Proteins**: These proteins span across the bilayer and can function as channels or carriers for molecules to pass through the membrane.
- **Peripheral Proteins**: These proteins are located on the inner or outer surface of the membrane and are not embedded within the bilayer.

5. **Correct Answer Identification**: Given the options provided in the question, the correct statement regarding the phospholipid bilayer in the fluid mosaic model is that it "has proteins embedded in it." The other options suggesting that the bilayer is sandwiched between protein layers or covered by a single protein layer are incorrect.

6. **Conclusion**: Therefore, the answer to the question is that in the fluid mosaic membrane model, the phospholipid bilayer has proteins embedded in it.

---