Give the diagrammatic representation of life cycle of Ectocarpus showing sexual and asexual reproduction. long question
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Answer:
(i) Asexual Reproduction in Ectocarpus:
The asexual reproduction takes places with the help of biflagellate zoospores. These zoospores are produced in unilocular and plurilocular sporangia
The sporophytic diploid plant forms two types of sporangia:
(a) Unilocular sporangia
(b) Plurilocular sporangia.
(ii) Sexual Reproduction in Ectocarpus:
The sexual reproduction may be isogamous, anisogamous or oogamous. Most of the Ectocarpus species are anisogamous. The gametes are biflagellate, motile and are produced in plurilocular gametangia borne on haploid or unisexual plants.
The plurilocular gametangia and plurilocular sporangia are similar in structure and development. The plurilocular gametangia are either sessile or stalked and vary in shape from ovate to siliquose. The plurilocular gametangia develop singly from the terminal cell of the lateral branchlets.
The gametangial initial divides transversely to form a row of 6-12 cells. Further divisions are transverse and vertical in these cells to make hundreds of cubical cells arranged in 20-40 transverse layers. The protoplast of each cubical cell in gametangium metamorphosis into single biflagellate pyriform gamete. The gametes are liberated in water through terminal or lateral pore in gametangium.