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Heterospory is the production of spores of two different sizes and sexes by the sporophytes of land plants. The smaller of these, the microspore , is male and the larger megaspore is female. Heterospory evolved during the Devonian period from isospory independently in several plant groups: the clubmosses , the ferns including the arborescent ...
Diagram showing the alternation of generations between a diploid sporophyte (bottom) and a haploid gametophyte (top) A sporophyte (/ ˈ s p ɔːr. ə ˌ f aɪ t /) is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores.
Spores of two distinct sizes (heterospory or anisospory): larger megaspores and smaller microspores. When the two kinds of spore are produced in different kinds of sporangia, these are called megasporangia and microsporangia. A megaspore often (but not always) develops at the expense of the other three cells resulting from meiosis, which abort.
According to Parsons, social systems rely on a system of language, and culture must exist in a society in order for it to qualify as a social system. [4] Parsons' work laid the foundations for the rest of the study of social systems theory and ignited the debate over what framework social systems should be built around, such as actions ...
In land plants, anisogamy is universal. As in animals, female and male gametes are called, respectively, eggs and sperm. In extant land plants, either the sporophyte or the gametophyte may be reduced (heteromorphic). [2]
At the micro level, social status and social roles are the most important components of social structure. Microsociology forms an important perspective in many fields of study, including modern psychosocial studies, conversational analysis and human-computer interaction. Microsociology continues to have a profound influence on research in all ...
Edward Burnett Tylor (1832–1917), a pioneer of anthropology, focused on the evolution of culture worldwide, noting that culture is an important part of every society and that it is also subject to a process of evolution. He believed that societies were at different stages of cultural development and that the purpose of anthropology was to ...
In the second sense, social order is contrasted to social chaos or disorder and refers to a stable state of society in which the existing social structure is accepted and maintained by its members. The problem of order or Hobbesian problem , which is central to much of sociology , political science and political philosophy , is the question of ...