Answer:
Following information are needed to classify an organism.
1. Unicellular or multicellular : First we have to see that from how many cells the body of organisms formed.
2. Composition of cell wall: Secondly we have to see the cell wall composition.
3. Prokaryotic or eukaryotic cell: We have to see the nucleus of organisms, if it has nucleus we can say that it is a eukaryotic cell.
4. Mode of nutrition: Mode of nutrition means is the organisms is autotroph or heterotroph.
If they have similarities, so it is placed in one group.