A Level Biology Practice Exam

What is the role of the cell wall in plant cells?

1. To facilitate photosynthesis

2. To provide a strong but flexible layer

3. To enhance nutrient absorption

4. To store genetic material

The correct answer is: To provide a strong but flexible layer

The cell wall in plant cells primarily serves the function of providing structural support and protection. It is composed mainly of cellulose, which lends rigidity and strength to the cell, allowing plants to maintain their shape and resist external pressures or stresses. This strength is crucial for plants, as they do not have a skeletal system to provide support. Additionally, the cell wall contributes to the overall integrity of plant tissues and helps prevent excessive water loss. In terms of flexibility, certain components within the wall, such as hemicellulose and pectin, allow the cell wall to accommodate growth while still maintaining a defined structure. This balance between strength and flexibility is essential for plants that rely on turgor pressure (the pressure of the cell contents against the cell wall) to keep them upright. While other aspects of plant function, such as photosynthesis and nutrient absorption, are important, they are not primary roles of the cell wall itself. For instance, chloroplasts within the cells are responsible for photosynthesis, and nutrient absorption mainly occurs through the roots and the cell membrane, not the cell wall. Similarly, genetic material is stored within the nucleus, not the cell wall.