You need a microcope to see teh smalletliving organism.They are made up of only one cell.That cells is an allporpuse cell.It is able to take in food,to grow andproduce to take and get rid of gases,to react,to produce energy and to move.

AMEBA: Is a one celled animalwhich lives in water.It has no fixed shape.Its is likes bag of jelly.It movesby pushingout a FOOT and flowing into it.It catches ist food in this way too