The middle lamella and two primary walls in the pit region together constitute the pit membrane, which has a thickening called

Options

A. Simple pit
B. Torus
C. Middle lamella
D. Primary cell wall

Answer

To solve the question about the thickening present in the pit membrane, we will analyze the options provided and determine the correct answer step by step.

### Step-by-Step Solution:

1. **Understanding the Components**: The question states that the middle lamella and the two primary walls in the pit region together constitute the pit membrane. The pit membrane is a crucial part of plant cells that facilitates communication and transport between adjacent cells.

2. **Identifying the Thickening**: The question asks for the thickening present in the pit membrane. We need to examine the options provided to find out which one correctly identifies this thickening.

3. **Evaluating the Options**:
- **Option 1: Simple Pits**: This option is incorrect. Simple pits are characterized by the absence of borders and do not refer to a thickening.
- **Option 2: Torus**: This option is correct. The torus is a circular thickening found in the middle of the pit membrane, which plays a role in regulating the flow of substances between cells.
- **Option 3: Middle Lamella**: This option is incorrect. The middle lamella is the layer that cements the primary walls of adjacent cells together but does not refer to a thickening in the pit membrane.
- **Option 4: Primary Cell Wall**: This option is also incorrect. The primary cell wall is the outermost layer of the cell wall and does not refer to a thickening in the pit region.

4. **Conclusion**: Based on the evaluation of the options, the correct answer is **Option 2: Torus**.

### Final Answer:
The thickening in the pit membrane is called **Torus**.

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