Final answer:
The cell wall provides structural support, protection, and shape to plant cells due to its composition of cellulose. It ensures the cell's water balance and prevents it from bursting, while still allowing the passage of water and nutrients through its pores.
Step-by-step explanation:
The cell wall is a crucial component of plant cells that provides numerous functions. Not only does it protect the cell by acting as a rigid covering, but it also provides structural support and maintains the shape of the cell. When it comes to support, the cell wall is particularly important because it contains cellulose, a polysaccharide composed of glucose units that contribute to the wall's rigidity.
Unlike an expanding balloon that thins out as it is blown up, the cell membrane and cell wall of a plant cell do not lose thickness during cell expansion, allowing for the maintenance of cell structure and integrity. Moreover, the cell wall controls the pressure within the plant cell, which is essential for the water balance and overall functioning of the cell. The crunch you experience when biting into raw vegetables like celery is the sound of breaking these protective, rigid walls.
Pores within the cell wall permit the passage of water and nutrients, which are vital for the plant's upkeep and growth. However, the wall also prevents cells from bursting by counteracting the pressure that builds up as water enters the cell. Some plants have a secondary cell wall that contains lignin, providing additional strength and protection.