What is Life? II

To go just a little further in depth as to what we meant last time when we discussed the characteristics of living things, I wanted to make a follow up post.  I’ve been putting this off, but it’s time to bite the bullet.

  • All living things are made up of 1 or more cells.  Cells are the basic unit of life.  Most are smaller than you can see with the naked eye, but they are composed of different parts called “organelles” that work together to allow the cell to function and reproduce.
  • All living things reproduce.  Reproduction creates offspring, which are similar, but not identical to the parent(s).  Reproduction can be sexual (two parents) or asexual (one parent).
  • All living things are based on a genetic code.  Usually that code is DNA (but sometimes RNA in the case of some viruses, which remember are technically not living), which is a molecule that tells your cells what to do in order to function.  Essentially the genetic code is a set of instructions for your cells.
  • All living things grow and develop.  Some organisms simply grow larger and prepare for reproduction.  Other organisms may develop legs or wings for movement, or teeth for chewing, or breasts for feeding their young.
  • All living things obtain and use energy.  Just as you need food, so do plants, fungi, and even bacteria.  The sum of all chemical reactions to build up and break down materials is called metabolism.
  • All living things respond to their environment.  A stimulus is a signal to which an organism responds.  When you get pollen in your nose, you sneeze.  When soil is moist and warm, a seed germinates.  When you turn on a light, roaches run away!
  • All living things maintain a stable internal environment.  No matter what goes on outside the body, all organisms keep their internal conditions stable.  The process to do this is called homeostasis.  When you get cold, your body tries to keep your internal temperature from dropping too much.  So you begin to move involuntarily.  We call this shivering.  Likewise, if you’re too hot, you’re body sweats to cool you off.
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