Answer the following question given this paragraph: 

Fungi used to be classified as plants. Now, they are known to have unique traits that set them apart from plants. For example, their cell walls contain chitin, not cellulose, and fungi absorb food rather than make their own. Below the level of the kingdom, fungi classification is controversial.


Q: Once classified as plants, fungi have chitin rather than cellulose in what cell structures?


A:
cell walls