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noun, plural: lives
noun, plural: lives
(1) A distinctive characteristic of a living organism from dead organism or non-living thing, as specifically distinguished by the capacity to grow, metabolize, respond (to stimuli), adapt, and reproduce
(2) The biota of a particular region
There is no consensus regarding the answer to the question as to when does life begin. Does it begin at the time of fertilization or the time before or after that? The origin of life is also contestable. Despite of the irresolute answer for questions about life, the basic characteristics of a living thing are as follows:

  • Organization. Living things are have an organized structure to perform a specific function. In particular, a living thing is made up of a single or a group of cell(s). A cell is the basic structural and functional unit of any organism.
  • Homeostasis. A life form would have an ability to keep up its existence, for instance, by regulating its internal environment to keep up a constant or favourable state.
  • Metabolism. A living thing would be capable of converting energy from chemicals into cellular components through anabolic reactions. It would also be capable of decomposing organic matter through catabolism.
  • Growth. A living thing grows, i.e. in size or in number.
  • Response. An organism has an ability to respond to stimuli or to its environment, usually through a series of metabolic reactions.
  • Reproduction. One of the hallmarks of life is the ability to reproduce, i.e. producing a new of its kind.
  • Adaptation. An organism is capable of changing through time to adapt to its environment.

Word origin: Old English līf (life, body)
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