Living things consists of the organisms like the plants, animals, fungi, protozoa and bacteria. These animals vary in the complexity of the body and have different number of cells in their body. Organisms like the plants and animals are made up of several different kinds of cells. These organisms are called multi-cellular organisms. On the other hand, organisms like the baker's yeast (a fungi) and a plethora of bacteria are single celled organisms. They are called unicellular organisms. Hence we can say that the living things are made up of at least one cell.