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

What role does the cell wall play in plant turgidity?

1. It limits the growth of the plant

2. It provides rigidity and support for the cell

3. It absorbs nutrients from the soil

4. It regulates gas exchange in the plant

The correct answer is: It provides rigidity and support for the cell

The role of the cell wall in plant turgidity is primarily to provide rigidity and support for the cell. The cell wall is a sturdy outer layer composed mainly of cellulose, which gives the plant cell its shape and helps it maintain structure. When plant cells take up water via osmosis, they swell and exert pressure against the cell wall. This pressure, known as turgor pressure, is essential for maintaining the plant's overall firmness and rigidity, allowing it to stand upright. The cell wall's ability to withstand this pressure is crucial for supporting not just individual cells, but the entire plant as a whole. Other options do not accurately describe the function of the cell wall in relation to turgidity. For instance, limiting the growth of the plant is not the role of the cell wall; rather, it supports growth. While the cell wall does play a part in nutrient absorption indirectly through the structure of the plant, it does not absorb nutrients itself. Similarly, while gas exchange is an important function in plants, this primarily occurs through structures like stomata and not directly through the cell wall.