Ahypothetical poison prevents nucleoli from carrying out their functions. which organelles would be affected by this poison?

The cell organelle that will be affected by this poison is the RIBOSOMES.
This is because, it is the nucleoli that produce the ribosomal sub-units which are assemble together to form ribosomes.
Nucleoli produce ribosomal sub units from protein and ribosomal RNA, it then send the sub-unit to the interior of the cell where they are assemble into ribosomes.  

Mitosis is one and the other is metoisis