Bacteria are always prokaryotes since they lack nucleus and membrane-bound organelles. Algae (both single-celled and multicellular ones) are more complex and th

Bacteria are always prokaryotes since they lack nucleus and membrane-bound organelles. Algae (both single-celled and multicellular ones) are more complex and thus eukaryotic. That being said, photosynthetic bacteria (cyanobacteria) do exist and were known as “blue-green algae” in the past, but that term has fallen out of use.