Plasma membrane is fluid structure due to presence of :-

Options

A. Carbohydrate
B. Lipid are arranged in fluid layer of proteins
C. Glycoprotein
D. Polysaccharide

Answer

### Step-by-Step Solution:

1. **Understanding the Plasma Membrane Structure**: The plasma membrane is primarily composed of a lipid bilayer, which consists of two layers of lipids. Each lipid molecule has a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails.

2. **Role of Lipids**: The fluidity of the plasma membrane is mainly due to the presence of lipids. The lipid molecules are not rigidly fixed in place; instead, they can move laterally within the layer, which contributes to the fluid nature of the membrane.

3. **Arrangement of Proteins**: Proteins are embedded within this lipid bilayer. There are different types of proteins:
- **Integral Proteins**: These span the entire membrane and are involved in various functions, including transport.
- **Peripheral Proteins**: These are attached to the exterior or interior surfaces of the membrane and play roles in signaling and maintaining the cell's shape.

4. **Presence of Carbohydrates**: Carbohydrates are also present on the plasma membrane, often attached to proteins (forming glycoproteins) or lipids (forming glycolipids). However, their primary role is not in providing fluidity but in cell recognition and signaling.

5. **Conclusion**: The main reason the plasma membrane is considered a fluid structure is due to the lipids arranged in a fluid layer, allowing for mobility and flexibility. Therefore, the correct answer to the question is that the plasma membrane is a fluid structure due to the presence of lipids arranged in a fluid layer of proteins.

### Final Answer:
The plasma membrane is a fluid structure due to the presence of lipids arranged in a fluid layer of proteins.

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