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Hormogonia are vegetative reproductive structure of
a. Spirogyra
b. Ulothrix
c. Oscillatoria
d. Yeast

Answer Verified Verified
Hint: Hormogonia are the motile filaments which are usually produced by the cyanobacteria in the vegetative reproduction, they are unicellular, filamentous bacteria, some of them contain heterocyst.

Complete answer:
- Whenever there is a change in the climate or any environmental stress, or if the cyanobacteria expose to new things it is converted to Hormogonia
- It plays a very important role in the case of nitrogen-fixing plant and the symbiosis of cyanobacteria because it exposes to nitrogen and converts to Hormogonia
- It is mainly seen in the genus Nostoc and their hosts.
- At the same time, the production of hormogonium inducing factor makes the cyanobacteria to differentiate and convert them into Hormogonia filaments and later after 3 to 4 hours dedifferentiated and comes back to normal.
- Based on species the length of Hormogonia varies, they range up to 100 meters length and they can travel by the gliding motility
- For Hormogonia to travel it requires the wet surface or vicious surface.
- An example of common cyanobacteria which can Hormogonia by vegetative reproduction is Nostoc, Oscillatoria.
- From the above-given options, Oscillatoria is the cyanobacteria and it is the correct answer
- Oscillatoria belong to the genus of filamentous cyanobacteria, it got this name because of its oscillation movement
- When it comes to the other option Spirogyra, it belongs to filamentous algae, it lives in freshwater and it has chloroplast.
- Ulothrix, they are also, none filamentous algae, live in fresh and marine water and thrive for low temperatures.
- Yeast belongs to the genus fungi, they are eukaryotic and they reproduce mostly by asexual reproduction that too by budding and the produced yeast cells are asymmetric nature.

Hence, The correct answer is option (C).

Note: The cyanobacteria or blue-green algae mainly reproduce by 3 methods, such as vegetative reproduction, sexual and asexual reproduction, whereas in the vegetative reproduction also they have types such as fragmentation, binary fission, and Hormogonia, etc.