Well defined nucleus is absent in

Well defined nucleus is absent in

  1. blue green algae
  2. diatoms
  3. algae
  4. yeast

Answer

Blue-green algae or cyanobacteria is a prokaryotic organism, i.e., it lacks well defined nucleus, whereas diatoms, algae and yeast all are eukaryotic organism, i.e., they show the presence of true nucleus and cell membrane bound organelles.

The correct option is A.