All cell membranes of multicellular organisms incorporate :

Options

A. transport proteins
B. receptor proteins
C. recognition proteins
D. all of these

Answer

**Step-by-Step Solution:**

1. **Understanding Cell Membranes**: Begin by recognizing that cell membranes are crucial structures in multicellular organisms. They serve as barriers that separate the interior of the cell from the external environment.

2. **Identifying Components of Cell Membranes**: Cell membranes are primarily composed of a phospholipid bilayer, but they also include various proteins that are embedded within or attached to the membrane.

3. **Types of Membrane Proteins**:
- **Transport Proteins**: These proteins facilitate the movement of substances across the cell membrane. They can help transport molecules into and out of the cell, ensuring that essential nutrients enter and waste products exit.
- **Receptor Proteins**: These proteins are involved in cell signaling. They change shape when specific ligands (molecules that bind to receptors) attach to them, triggering a response inside the cell.
- **Recognition Proteins**: These proteins help the immune system recognize foreign substances. They are often involved in identifying pathogens and play a role in cell communication.

4. **Conclusion**: Since all these types of proteins (transport, receptor, and recognition) are integral to the function of cell membranes in multicellular organisms, the correct answer to the question is that all cell membranes of multicellular organisms incorporate these proteins.

5. **Final Answer**: Therefore, the answer is "All of these" as all mentioned proteins are present in the cell membranes of multicellular organisms.

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