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A life form (also spelled life-form or lifeform) is an entity that is living, [1] [2] such as plants , animals , and fungi . It is estimated that more than 99% of all species that ever existed on Earth, amounting to over five billion species, [3] are extinct. [4] [5] Earth is the only celestial body known to harbor life forms. No form of ...
The definition of life has long been a challenge for scientists and philosophers. [2] [3] [4] This is partially because life is a process, not a substance. [5] [6] [7] This is complicated by a lack of knowledge of the characteristics of living entities, if any, that may have developed outside Earth.
Living systems. Living systems are life forms (or, more colloquially known as living things) treated as a system. They are said to be open self-organizing and said to interact with their environment. These systems are maintained by flows of information, energy and matter. Multiple theories of living systems have been proposed.
The eukaryotes ( / juːˈkærioʊts, - əts / yoo-KARR-ee-ohts, -əts) [ 5] constitute the domain of Eukarya or Eukaryota, organisms whose cells have a membrane-bound nucleus. All animals, plants, fungi, and many unicellular organisms are eukaryotes.
Organism. An organism is defined in a medical dictionary as any living thing that functions as an individual. [ 1] Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have been proposed to define what is an organism.
6. Leaf life-forms: based on the character (form, size, duration, structure, etc.) of the leaves (e.g., Raunkiær, 1916). Later authors have combined these or other types of unidimensional life-form schemes into more complex schemes, in which life-forms are defined as combinations of states of several characters.
686465. Anatomical terminology. [ edit on Wikidata] The cell is the basic structural and functional unit of all forms of life. Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word cellula meaning 'small room'.
Biodiversity. An example of the biodiversity of fungi in a forest in North Saskatchewan (in this photo, there are also leaf lichens and mosses ). Biodiversity (or biological diversity) is the variety and variability of life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem ...