OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

Why do plant cell walls prevent loss of shape in flaccid plants?

1. They are flexible and can change shape

2. They maintain structure even with low turgor pressure

3. They absorb additional water quickly

4. They are rigid and prevent significant deformation

The correct answer is: They are rigid and prevent significant deformation

In plant cells, the cell wall plays a crucial role in maintaining the overall structure and shape of the plant. The statement that the cell walls are rigid and prevent significant deformation is essential in understanding how plants cope with changes in water availability. When a plant becomes flaccid due to a loss of water, the internal pressure (turgor pressure) decreases. However, the rigid structure of the cell wall provides resistance to external forces, helping to keep the cell from collapsing entirely. This rigidity ensures that the plant retains its overall shape, even when the cells do not have optimal turgor pressure. It acts as a protective boundary that prevents cells from being overly deformed, thereby allowing the plant to maintain its architectural integrity. In essence, while the cells themselves may lose water and become flaccid, the firmness of the cell wall is what prevents them from losing their general structure and shape. This is vital for the plant's health and ability to recover when conditions improve.