Answer the following question given this paragraph: 

The aim of basic science is to discover new knowledge. It leads to a better understanding of the natural world. It doesn’t necessarily have any practical use. An example of basic research in life science is studying how yeast cells grow and divide. Yeasts are single-celled organisms that are easy to study. By studying yeast cells, life scientists discovered the series of events called the cell cycle. The cell cycle works not only in yeasts but in all other organisms with similar cells. Therefore, this basic research made a major contribution to our understanding of living things. Watch the following animation to learn more about the basic yeast research and the cell cycle. You can also see yeast cells dividing.


Q: What kind of organisms are yeasts?


A:
single-celled