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  2. SimEarth - Wikipedia

    en.wikipedia.org/wiki/SimEarth

    A planet without any water can have oceans brought back if hit by an "ice meteor" (a.k.a. a comet). Many things have to be kept within a certain balanced range for a planet to be able to support multicellular animal life; outside this range, only single-celled lifeforms, plants, robots, and lifeforms that have been civilized can survive.

  3. Rare Earth hypothesis - Wikipedia

    en.wikipedia.org/wiki/Rare_Earth_hypothesis

    The Rare Earth hypothesis argues that planets with complex life, like Earth, are exceptionally rare.. In planetary astronomy and astrobiology, the Rare Earth hypothesis argues that the origin of life and the evolution of biological complexity, such as sexually reproducing, multicellular organisms on Earth, and subsequently human intelligence, required an improbable combination of astrophysical ...

  4. Anaerobic organism - Wikipedia

    en.wikipedia.org/wiki/Anaerobic_organism

    Facultative anaerobes can grow with or without oxygen because they can metabolize energy aerobically or anaerobically. They gather mostly at the top because aerobic respiration generates more adenosine triphosphate (ATP) than either fermentation or anaerobic respiration. Microaerophiles need oxygen because they cannot ferment or respire ...

  5. Outline of life forms - Wikipedia

    en.wikipedia.org/wiki/Outline_of_life_forms

    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 ...

  6. Loricifera - Wikipedia

    en.wikipedia.org/wiki/Loricifera

    The newly reported animals complete their life cycle in the total absence of light and oxygen, and they are less than a millimetre in size. [19] They were collected from a deep basin at the bottom of the Mediterranean Sea, where they inhabit a nearly salt-saturated brine that, because of its density (> 1.2 g/cm 3 ), does not mix with the waters ...

  7. Mycoplasma - Wikipedia

    en.wikipedia.org/wiki/Mycoplasma

    Mycoplasma species (like the other species of the class Mollicutes) are among the smallest organisms yet discovered, [2] can survive without oxygen, and come in various shapes. For example, M. genitalium is flask-shaped (about 300 x 600 nm ), while M. pneumoniae is more elongated (about 100 x 1000 nm ), many Mycoplasma species are coccoid .

  8. Hypothetical types of biochemistry - Wikipedia

    en.wikipedia.org/wiki/Hypothetical_types_of...

    Most alternative solvents are not stable in an oxygen-rich atmosphere, so it is highly unlikely that those liquids could support aerobic life. A large temperature range over which it is liquid. High solubility of oxygen and carbon dioxide at room temperature supporting the evolution of aerobic aquatic plant and animal life.

  9. Obligate aerobe - Wikipedia

    en.wikipedia.org/wiki/Obligate_aerobe

    They gather at the top of the tube where the oxygen concentration is highest. 2: Obligate anaerobes are poisoned by oxygen, so they gather at the bottom of the tube where the oxygen concentration is lowest. 3: Facultative anaerobes can grow with or without oxygen because they can metabolise energy aerobically or anaerobically. They gather ...