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2. The state of a living organism is never static, and all its physiological and energy parameters are always in a state of continuous fluctuations relative to the average values both in frequency and amplitude. This principle of functioning of living organisms provides them with the properties of phenotypic adaptation and a number of others.
Non-cellular life, also known as acellular life, is life that exists without a cellular structure for at least part of its life cycle. [1] Historically, most definitions of life postulated that an organism must be composed of one or more cells, [2] but, for some, this is no longer considered necessary, and modern criteria allow for forms of life based on other structural arrangements.
The mechanism, now ubiquitous in living cells, powers energy conversion in micro-organisms and in the mitochondria of eukaryotes, making it a likely candidate for early life. [ 172 ] [ 173 ] Mitochondria produce adenosine triphosphate (ATP), the energy currency of the cell used to drive cellular processes such as chemical syntheses.
For example, in the carbon cycle, atmospheric carbon dioxide is absorbed by plants through photosynthesis, which converts it into organic compounds that are used by organisms for energy and growth. Carbon is then released back into the atmosphere through respiration and decomposition.
Bioenergetics is a field in biochemistry and cell biology that concerns energy flow through living systems. [1] This is an active area of biological research that includes the study of the transformation of energy in living organisms and the study of thousands of different cellular processes such as cellular respiration and the many other metabolic and enzymatic processes that lead to ...
Animal corpses, like this African buffalo, are recycled by the ecosystem, providing energy and nutrients for living organisms. Death is the termination of all vital functions or life processes in an organism or cell. [31] [32] One of the challenges in defining death is in distinguishing it from life.
The community of living organisms in conjunction with the nonliving components (e.g., water, light, radiation, temperature, humidity, atmosphere, acidity, and soil) of their environment is called an ecosystem. [147] [148] [149] These biotic and abiotic components are linked together through nutrient cycles and energy flows. [150]
Ecosystem respiration is the sum of all respiration occurring by the living organisms in a specific ecosystem. [1] The two main processes that contribute to ecosystem respiration are photosynthesis and cellular respiration. Photosynthesis uses carbon-dioxide and water, in the presence of sunlight to produce glucose and oxygen whereas cellular ...