Question

Algae are known to reproduce asexually by a variety of spores under different environmental conditions. Name these spores and the conditions under which they are produced

Answer 1

Zoospores:

• Zoospores are flagellated asexual structures, which are formed in the reproductive body called zoosporangium.
• These can be biflagellate e.g., Chlamydomonas or quadriflagellate e.g., Ulothrix.
• They move in water before they germinate to make new plants. These are formed under favourable conditions.

Aplanospores

• Aplanospores are non-motile structures and their protoplasm is surrounded by a thin cell wall. They release and form new plants, e.g., Ulothrix.
• These are formed under unfavorable conditions.

Akinetes:

• Akinetes are thick walled, non-motile structures like aplanospores. They form new thalli. e.g., Anabaena.
• These are formed under unfavorable conditions as a method of perennation.

Hypnospores:

• Hypnospores are thick walled structures. Under prolonged unfavorable conditions, the protoplasm of hypnospores divides to produce cysts. The cysts form new thallus. e.g., Chlamydomonas nivalis.
• These are formed during unfavorable conditions.

Tetraspores

• Tetraspores are non-motile spores formed in some members of Rhodophyceae and Phaeophyceae.
• In Polysiphonia, tetra spores are formed in tetra sporangia by reduction division on special tetrasporophyte plants.

Autospores

• Autospores are aplanospores like structures.
• These are similar to the parent cell.
• These acquire all characteristics of parent cells before the discharge process from sporangium in Chlorella.