ABSTRACT
https://www.niso.org/standards/z39-96/ns/oasis-exchange/table"> Key Notes Life cycles in the Archaeplastida: chlorophytes Many members of the Archaeplastida have a haploid vegetative phase, and gametes (motile or nonmotile) are formed by the differentiation of a vegetative cell. Zygote formation is followed bymeiosis, producing haploid progeny cells. Other species have a diploid vegetative phase and produce haploid gametes by meiosis. Life cycles in the Excavata, Chromalveolata, and Amoebozoa Vegetative growth is associated with mitosis and cell division. Cell division can be by budding, binary or multiple divisions. Haploid life cycles are characterized by meiosis occurring at germination of the diploid zygote. Haploid cells form haploid gametes that fuse to form the diploid zygote. Species with a diploid life history are haploid only at gamete formation. Life cycles in excavates Life cycles in the excavates are characterized by asexual reproduction by longitudinal binary fission. Sexual reproduction is seen in the parasitic flagellates. Life cycles in Chromalveolata Asexual reproduction in ciliates is by homothetogenic cell division. Sexual reproduction occurs and the dominant phase of the life cycle is diploid. Dinoflagellates are haploid during most of their life cycle and reproduce by binary fission. Sexual reproduction is by the formation of macrogametes and microgametes. Asexual reproduction in the apicomplexa is characterized by multiple fissions. Sexual reproduction occurs in alternative hosts. In diatoms, diploid vegetative cells of diatoms reproduce asexuallyby mitosis. Centric diatoms form one or several macrogametes in an oogonium, fertilized by motile microgametes to generate a zygote within an auxospore. Chrysophyte asexual reproduction is by binary fission, and sexual reproduction results in a statospore. Asexual reproduction in oomycetes and related species is usually via flagellate motile diploid zoospores released from terminal sporangia. Sexual reproduction involves haploid gametes produced by terminal or subterminal antheridia and oogonia. Hyphochytrids reproduce via a multinucleate protoplast that is formed in the host cell, then releasing cysts into the soil that germinate into biflagellate zoospores able to invade new host plant roots. Life cycles in Amoebozoa Cellular slime mold amebae aggregate upon starvation to yield a multicellular pseudoplasmodium that differentiates into a fruiting body and generates haploid spores. Amebae of the acellular slime molds fuse to form a diploid cell (or this is produced via haploid flagellated cells), which grows into a large multinucleate plasmodium. Sporangia arise and meiosis within them generates haploid spores that germinate to release amebae. Pathogenic amebae have a simple life cycle existing as cysts outside the host and as amebae inside the host. Related topics (H3) Cell division and ploidy (I1) Fungal structure and growth 235
