Do Meiosis and Mitosis occur in all organisms?

No, not all organisms.

Explanation:

Hi there,

As you may continue to learn in biology, not all organisms go through the process of mitosis/meiosis. Well known examples are prokaryotes, such as  bacteria and archaea, ancient organisms that replicate via binary fission, budding, and/or fragmenting

Mitosis and Meiosis only occur in eukaryotes and unique to them.

thanks,

i would say the prokaryotic cells the prokaryotic cells are less complex, are usually found only in unicellular organisms and have more limited capabilities than eukaryotic cells.