Composition of Middle Lamella

The middle lamella is a thin layer that separates adjacent plant cells. It is composed mainly of calcium pectate, making option B the correct answer. Calcium pectate is a complex polysaccharide that plays a crucial role in cell adhesion and the formation of the middle lamella.

Explanation:

1. Middle Lamella
The middle lamella is a layer of pectic substances that lies between adjacent plant cells. It is the outermost layer of the primary cell wall and plays a crucial role in cell adhesion and cell-to-cell communication.

2. Calcium Pectate
Calcium pectate is a complex polysaccharide that is composed of pectin molecules cross-linked by calcium ions. Pectin is a type of polysaccharide found in the primary cell wall of plants. It is made up of a chain of galacturonic acid molecules.

3. Cell Adhesion
The middle lamella is responsible for the adhesion of adjacent plant cells. Calcium pectate acts as a cementing material, holding the cells together. The calcium ions present in the middle lamella form bridges between the pectin molecules, providing structural support and strength to the cell wall.

4. Cell-to-Cell Communication
The middle lamella also facilitates cell-to-cell communication. It forms channels called plasmodesmata that connect the cytoplasm of adjacent cells. These channels allow the exchange of nutrients, water, and signaling molecules between cells.

5. Other Components
Although calcium pectate is the main component of the middle lamella, it also contains other substances such as hemicellulose, cellulose, and proteins. Hemicellulose is a polysaccharide that provides structural support to the cell wall, while cellulose forms the main component of the primary cell wall.

Conclusion

In conclusion, the middle lamella is mainly composed of calcium pectate. This complex polysaccharide, along with other components such as hemicellulose and proteins, plays a crucial role in cell adhesion and cell-to-cell communication. It provides structural support and strength to the cell wall and facilitates the exchange of nutrients and signaling molecules between adjacent plant cells.