The correct option is (c).
Explanation
The cell wall is a rigid, semi-permeable protective layer found in the cells of plants, fungi, bacteria, and algae. It is located external to the plasma membrane and is a defining characteristic that distinguishes plant cells from animal cells.
Statement-wise Analysis:
- Statement 1 is Incorrect. The plant cell wall is primarily composed of cellulose, which is a complex carbohydrate (polysaccharide). While it may contain hemicellulose, pectins, and small amounts of proteins, the dominant structural component is cellulose, not protein. In contrast, fungal cell walls are made of chitin, and bacterial cell walls are made of peptidoglycan.
- Statement 2 is Correct. The cell wall is a non-living, rigid structure that lies outside the plasma membrane. Unlike the plasma membrane, which is selectively permeable and living, the cell wall is generally permeable and provides a fixed shape to the cell.
- Statement 3 is Correct. The main function of the cell wall is to provide structural strength and support to the plant. It protects the cell from mechanical injury and infection. It also allows plant cells to withstand changes in osmotic pressure (e.g., preventing bursting in hypotonic solutions).
Key Takeaway:
The plant cell wall is a non-living, rigid boundary composed mainly of cellulose. Its primary roles are to provide mechanical support, maintain cell shape, and protect the cell from external stress.