Answer:
1. CELL
2. REPRODUCTION
3. IRRITABILITY
Step-by-step explanation:
1. All living organisms are composed of CELLS, which according to the cell theory as proposed in the 1800's is the smallest structural and functional unit of life.
2. REPRODUCTION is a characteristics possessed by all living things. It is the process whereby living organisms/things create new living things.
3. IRRITABILITY is another characteristics of living things, which is the process whereby living things respond to changes in their environment called STIMULUS e.g heat, nutrient stress e.t.c.