Yes, fungi can have only one cell. These single-celled fungi are called yeasts.

While many fungi, like mushrooms, are multicellular, yeasts are unicellular organisms. They are classified as fungi due to their similar characteristics, such as:

* Cell wall composition: Both yeasts and multicellular fungi have cell walls made of chitin.

* Nutritional mode: They are heterotrophic, meaning they obtain nutrients from other organisms.

* Reproduction: They can reproduce both sexually and asexually.

So, while many fungi are multicellular, yeasts are a good example of single-celled fungi.