True nucleus is absent in
- Vaucheria
- Volvox
- Anabaena
- Mucor.
Answer
(3) Anabaena
Solution
As per NCERT, cyanobacteria (blue-green algae) such as Anabaena and Nostoc belong to Kingdom Monera; they are prokaryotes.
∵ Prokaryotic cells have no well-defined nucleus bounded by a nuclear membrane (the genetic material is naked, in the nucleoid),
∴ a true nucleus is absent in Anabaena.
Vaucheria (alga), Volvox (green alga) and Mucor (fungus) are eukaryotes with a true nucleus.
Answer: (3)