Question

Hormogonia are produced in
A.Oscillatoria
B.Ulothrix
C.Spirogyra
D.Yeast

Answer 1

Hint: Hormogonia are motile filaments of cells formed by some of the cyanobacteria. They are usually formed during vegetative reproduction in unicellular, filamentous cyanobacteria.

Complete answer:
Hormogonia can break into fragments. The hormogonia have the ability to grow into new filaments during the process of vegetative reproduction. The filaments undergo breakage in the presence of dead cells called necridia. Let us analyze the options to find out the correct option.

Option A: Oscillatoria is a genus of filamentous cyanobacteria. It is named so because of oscillation observed in its movement. It forms long filaments of cells which can break into fragments called hormogonia. The hormogonia can further grow into a new long filament. Therefore, this is the correct option.

Option B: Ulothrix is a genus of non-branching filamentous green algae. They are found in fresh and marine water. They reproduce through vegetative reproduction mode and usually thrive in low temperatures. They do not have hormogonia. Therefore, this is the incorrect option.

Option C: Spirogyra is also called water silk. It is a filamentous charophyte green algae which shows spiral arrangement of the chloroplasts. It is commonly found in freshwater and does not have the presence of hormogonia. Therefore, this is the incorrect option.

Option D: Yeasts are eukaryotic single-celled microorganisms which are the members of the fungus kingdom. They do not have hormogonia. Therefore, this is the incorrect option.

Hence, the correct answer is option (A)

Note: Development of hormogonia is essential for the development of nitrogen fixing plant cyanobacteria symbiosis mostly between cyanobacteria of genus Nostoc and their host.