Final answer:
The organelle or structure that is absent in plant cells is the centrosome.
Step-by-step explanation:
The organelle or structure that is absent in plant cells is the centrosome. While both animal and plant cells have microtubule organizing centers (MTOCs), animal cells also have centrioles associated with the MTOC: a complex called the centrosome. Animal cells each have a centrosome and lysosomes, whereas most plant cells do not.