Which organisms have cell walls?

• A. Animal cells
• B. Plant and fungal cells
• C. Human cells
• D. All animal cells

Answer: (B)

Cell walls are rigid structures outside the plasma membrane that provide support and protect the cell from osmotic damage. Plant cells have walls made mainly of cellulose, giving plants their characteristic bulk and rigidity. Fungal cells also have walls, but theirs are made of chitin, a tough polysaccharide. In contrast, animal and human cells do not have cell walls; they rely on the flexible membrane and, in multicellular animals, extracellular matrix for structure. So, the organisms that have cell walls in this context are plants and fungi.