What werer the criteria of the 2 kindom system biological classification and what were the drawbacks of the system?

Drawbacks of 2 kindom classification are as follows:-
1) Both Eukaryotes and prokaryotes were placed together.
2) In plant knigdom there were species which were photosynthetic and non photosynthetic, so there were also placed together.
3) There were some animals which show both animals as well as plants character, so no fixed position was there for them.  
E.g. Euglena

 

 

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