Question

what are the drawbacks of the cell theory

Answer 1

the first cell on earth was not originated from any pre existing cell

Answer 2

Some of the objections or drawbacks were slated against the cell theory:

1) Virus are acellular entities or organisms which do not have a cell machinery. Even then they are considered to be organisms in this cell theory.
2) In some of the organisms, the body is not quite differentiated into the cells though it may have numerous nuclei present in them (coenocytes, such as, Rhizopus).
3) Protozoans and many thallophytes have a unicellular or single called differentiated into the body (such as, Acetabularia) which cannot be delivered and divided into cellular structures and cells, however, they are also acellular.
4) Bacteria and Cyanobacteria do not have or have absence of nucleus and membrane bound organelles.
5) RBCs and sieve tube cells continue to live and function without a proper nucleus.
6) Protoplasm is replaced by nonliving materials in their surface of the cells of skin and cork.
7) Schleiden and Schwann did not know the mechanism of cell formation. Schwann believed cells to produce and develop spontaneously just like a crystal. Schleiden thought new cells are developed from cytoblast or nucleus.

These were some adequate objections against the formulated and modern cell theory.