**Answer:**

Collenchyma is a type of simple mechanical tissue with non-lignified walls. It provides mechanical support to the plant and helps in maintaining the shape and structure of the plant organs.

**Collenchyma tissue structure:**
Collenchyma cells are elongated with thickened corners and unevenly thickened primary walls. The thickening is due to the deposition of cellulose, hemicellulose, and pectin. The thickening provides strength and flexibility to the cells, making them ideal for providing mechanical support.

**Functions of Collenchyma tissue:**
1. Mechanical support: Collenchyma tissue provides support to young parts of the plant, such as stems, petioles, and leaf veins. It helps in resisting bending and stretching forces, preventing the plant from collapsing under its own weight.
2. Flexibility: The uneven thickening of the cell walls allows for flexibility, enabling the plant to withstand external pressure and wind.
3. Growth: Collenchyma tissue can undergo cell division and enlargement, contributing to the growth of the plant organ in which it is present.

**Comparison with other tissues:**
1. Parenchyma: Parenchyma cells have thin cell walls and serve various functions in the plant, such as photosynthesis, storage, and secretion. However, they lack the thickened cell walls and mechanical strength characteristic of collenchyma tissue.
2. Sclerenchyma: Sclerenchyma cells have heavily thickened and lignified secondary walls, which provide rigid support to the plant. Unlike collenchyma, sclerenchyma cells are dead at maturity and cannot elongate or divide.
3. Chlorenchyma: Chlorenchyma cells contain chloroplasts and are responsible for photosynthesis. They have relatively thin cell walls and do not provide significant mechanical support.

**Conclusion:**
In conclusion, collenchyma is a type of simple mechanical tissue with non-lignified walls. Its thickened cell walls provide strength and flexibility, making it ideal for supporting young plant organs. Other tissues like parenchyma, sclerenchyma, and chlorenchyma have different structural characteristics and functions.

Collenchyma--- it is a living mechanical tissue it's cell wall is made up of cellulose, hemicellulose and pectin.(i.e. non-lignified)...