question_answer 40)

  Algae are known to reproduce asexually by variety of spores under different environmental conditions. Name these spores and the conditions under which they are produced. Asexual reproduction in algae is very common mean of reproduction.

Answer:

                  Algae and their spores exhibit enormous diversify and they vary greatly in their level of specialization. Asexual reproduction by spores and their types are described below By Zoospores These are mobile flagellated spores. In which protoplasm of each vegetative cell undergoes repeated longitudnal division either into 2 or 4 rarely 8 or 16daughter protoplast. The parent cell loses its flagella, before the onset of division. After the last series of division, each daughter protoplast secretes a cell wall and neuromotor apparatus that develops two flagella, eyespots and contractile vacuoles. Thus, each of the daughter cell formed resembles the parent cell in all aspects except the small size. Formation of zoospores is very common under favourable conditions. (b) By Plano spores These are the non-motile spores. They are asexually formed with in a cell, in this the protoplast withdraws itself from the parent wall, rounds up and develops into a Plano spores which may either germinate directly or may divide to produce zoo spores. (c) By Hypnospores In this, the protoplasm withdraws from the cell wall, rounds up an develop a thick wall under un favourable condition. These resting spores are called as, hypnospores. They are red in colour due to presence of haematochrome. e.g., Vaucheria, Ulothrix. (d) Akinetes These are special vegetative thick walled cells present in the filaments which remain under dorment state and return to germination under favourable condition and can also with stand unfavourable condition as Spirogyra. (e) Statospores This are thick walled spores produced in diatoms. (f) .Neutral Spores In some algae, the protoplast, of vegetative cells directly functions as spores called as neutral spores (e.g., Ectocarpus).