While they are single-celled organisms like bacteria, they are classified as fungi due to their distinct characteristics, such as:

* Cell wall composition: Yeast cell walls contain chitin, a polymer that is also found in the cell walls of other fungi.

* Mode of nutrition: Yeast obtain nutrients through absorption, similar to other fungi.

* Reproduction: Yeast reproduce by budding or forming spores, which is a characteristic of fungi.

So, while yeast may seem similar to bacteria in size and appearance, they are fundamentally different and belong to the fungal kingdom.