I believe that the basic unit of structure and function in protists and monerans is the cell. This is because cells are basic unit of structure and function of all living things. A cell is the smallest unit of life, it is the basic membrane-bound unit that contains the fundamental molecules of life and of which all living things are composed.
The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cellsarise from existing cells. Rudolf Virchow later made important contributions to this theory. ... Thecell is the fundamental unit of structure and function in living things.
True, a lot of cultivated fields use fertilizers that can be harmful to fish
The answer to your question is digestive.
It shows the evolution of an being. "Fossil record, history of life as documented by fossils, the remains or imprints of the organisms from earlier geological periods preserved in sedimentary rock." from https://www.britannica.com/science/fossil-record
