ribosomes
vacuole
a cell membrane!
The largest organelle in most plant cells will be the vacuole.
Mitochondria
the nucleus
It should be the vacuole, because all cells, even the red-blood cells and xylem cells have vacuoles. Basically my definition of "universal cell organelle" means an organelle which is present in all cells.
All cells, whether they are eukaryotic or prokaryotic, have organelles that exist within its cell membrane.
The chromosome(s). In eukaryotic cells there are several linear chromosomes enclosed in an organelle called the nucleus. In prokaryotic cells there is one circular chromosome and several tiny circular plasmids, but no nucleus.
An organelle
The organelle that is responsible for photosynthesis in cells is the chloroplast, which contain chlorophyll.
cell membrane
mitochondria and nucleus