Yeast can reproduce by which is when daughter cells arise as an outgrowth of the parent cell.

Budding

Budding is a asexual mode of reproduction in unicellular simple organisms. In budding a small protuberance or outgrowth develops as daughter cell on the parent cell called as bud. The bud enlarged in size and gets detached from the parent organism and grows as a new organism.  

unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.