What is Life?

If Biology is the study of life, how do we define life?  Is there one characteristic that defines all life?  If you ask a room of students “how can you tell if something is alive” you’ll hear things like “poke it with a stick and see if it moves.”  Unfortunately, that isn’t right.  In fact, there is not one characteristic that defines all life.  Living things are defined by a few characteristics.

All living things:

  • are made up of 1 or more cells.
  • reproduce.
  • are based on a genetic code .
  • grow and develop.
  • obtain and use energy.
  • respond to their environment.
  • maintain a stable internal environment.

Even nonliving things can meet some of these descriptions, so it’s important to be able to tell living from nonliving. For example, a car obtains and uses energy and maintains a stable internal environment.  Some can even respond to their (external) environment!  To be defined as living an object must meet ALL of these requirements.

Technically, viruses don’t meet this description of life and many scientists don’t  consider them to be living things.  However, since they act like living things, they are studied under the umbrella of biology in a field either specifically called Virology or as a broader biology field called Microbiology.


Biology: The Study of Life


Biology: What Is It and Why Should I Care?

Biology comes from the Ancient Greek βιολογία, or more informatively the root bio & suffix -logy.  In simplest terms, bio = “life” and -logy = “study of”.  Biology is the study of life.  Another way of saying this would be to say that biology is the study of organisms (“living beings” or “living things” as most like to say).

As for why you should care, well since you are a living thing, it might be important for you to understand things that go on with regards to your body.  Biology can get in as much detail as you want to study.  In fact, some universities require biology majors to take a little bit of everything while others require you to pick a specific area of concentration.  Much like there’s the doctor you go to when you don’t know what’s wrong (a general practice doctor or a “family doctor”), you can also go to a specific doctor for specific problems (for example, you’d see a cardiologist for heart problems).

Here are a few of the fields found in biology (with the subject matter in parentheses):

  • Anatomy (body structure)
  • Botany (plants)
  • Cytology (cells)
  • Ecology (animals’ interaction with their environment)
  • Genetics (genes & heredity)
  • Microbiology (microorganisms)
    • Parasitology (parasites)
    • Virology (viruses)
  • Mycology (fungi)
  • Physiology (body function)
  • Zoology (animals)
    • Herpetology (snakes)
    • Ornithology (birds)
    • Paleontology (ancient organisms)

Click here for a more comprehensive, though probably not exhaustive, list.

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