Question

What criteria do we use to decide whether something is alive?

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Answer 1

Walking, breathing, growth and other visible changes can be used to determine whether something is alive or dead. However some living things will have changes that are not visible to our eye; Hence, presence of life process is a fundamental criteria to decide whether something is alive.

Answer 2

Any visible movement such as walking, breathing, or growing is generally used to decide whether something is alive or not. However, a living organism can also have movements, which are not visible to the naked eye.