The concept of life encompasses any system capable of performing essential functions such as eating, metabolizing, excreting, breathing, moving, growing, reproducing, and responding to external stimuli.
In more detail, the concept of life can be examined through several key aspects:
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Metabolism: This is the sum of all chemical processes that occur within a living organism in order to maintain life. It includes processes such as extracting energy from nutrients (eating) and converting that energy into usable forms.
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Excretion: Living organisms need to eliminate waste products produced by metabolic processes. This process is known as excretion.
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Respiration: Many, but not all, life forms need to take in gases (such as oxygen) and release waste gases (such as carbon dioxide). This gas exchange is necessary for energy production and other metabolic functions.
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Movement: This is not necessarily locomotion (walking or swimming). It can also include internal movement, such as the transport of substances within an organism.
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Growth: Living organisms increase in size or complexity over time, typically through the accumulation of biomass.
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Reproduction: This is the process by which organisms create new individuals, ensuring the continuation of their species.
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Responsiveness (Irritability): Living organisms can detect and respond to changes in their environment, allowing them to adapt and survive. These changes can be external stimuli like light, temperature, or chemicals.
These characteristics, taken together, distinguish living organisms from non-living matter. It is important to note that there can be edge cases and debates at the boundaries of what is considered "life" (e.g., viruses). The definition offered here represents the generally accepted understanding.
