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Some species of red algae have a complex triphasic alternation of generations, in which there is a gametophyte phase and two distinct sporophyte phases. For further information, see Red algae: Reproduction. Land plants all have heteromorphic (anisomorphic) alternation of generations, in which the sporophyte and gametophyte are distinctly different.
This type of life cycle, involving alternation between two multicellular phases, the sexual haploid gametophyte and asexual diploid sporophyte, is known as alternation of generations. The evolution of sexual reproduction is considered paradoxical, [ 12 ] because asexual reproduction should be able to outperform it as every young organism ...
The gradual evolution of an independent, sporophyte phase was viewed by Bower as being closely related to the transition from aquatic to terrestrial plant life on Earth. Evidence supporting this theory can be found in the life cycle of modern Bryophytes in which the sporophyte is physiologically dependent on the gametophyte .
Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes.Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes, or by mitosis.
This cycle is known as alternation of generations. The spores of seed plants are produced internally, and the megaspores (formed within the ovules) and the microspores are involved in the formation of more complex structures that form the dispersal units, the seeds and pollen grains.
This is an accepted version of this page This is the latest accepted revision, reviewed on 4 February 2025. Union of opposite-sex gametes in sexual reproduction to form a zygote This article is about fertilisation in animals and plants. For fertilisation in humans specifically, see Human fertilization. For soil improvement, see Fertilizer. "Conceive" redirects here. For the health magazine ...
Sporophyte – Diploid multicellular stage in the life cycle of a plant or alga; Alternation of generations – Reproductive cycle of plants and algae; Archegonium – Organ of the gametophyte of certain plants, producing and containing the ovum; Antheridium – Part of a plant producing and containing male gametes
In some plants the gametophyte is not only small-sized but also short-lived; in other plants and many algae, the gametophyte is the "dominant" stage of the life cycle. [19] Haplodiplonts are: In archaeplastidans: red algae (which have two sporophyte generations), some green algae (e.g., Ulva), land plants [8] [9] In stramenopiles: most brown ...