How Do We Know if
Something is Living or
Not?
Well...it depends on who you ask
We are going to say there are six.
Living things are made of cells.
Living things respond to their environment.
Living things reproduce.
Living things use energy.
Living things eliminate waste.
Living things grow and mature.
1. Living Things are Made of Cells
We will later learn about the structure and function of
cells.
A cell is the smallest thing to be alive.
Some living things (organisms) are only one
cell. Others are multicellular.
We often call cells the building blocks of life.
Examples of single-celled
organisms
Examples of Cells from
Multicellular Organisms
2. Living Things Respond to their
Environment
All organisms have the ability to “sense”
the world around them so that they may
survive.
The things they sense are called stimuli
and may include light, temperature,
pressure, gravity, odor, sound, color,
water and so many other conditions.
Living Things Respond
(continued)
Organisms need to sense their environment
in order to maintain HOMEOSTASIS. This is
the ability of an organism to maintain
“body function” in response the
environmental changes.
We shiver and sweat to keep our body
temperature and its healthy temperature.
Examples of Response to Stimuli
Sensing fewer daylight hours
and lower temperatures, many
animals begin to hoard food
and may undergo some level
of hibernation in order to save
energy until spring returns.
Plants move their leaves
toward the sun’s rays so
they maximize
photosynthesis.
Many bird species
migrate in order to access
food and nesting
resources as seasons
and competition change.
3. Living Things Reproduce
They make more of themselves.
More about this later.
4. Living Things Use Energy
5. Living Things Eliminate Waste
During the process of
photosynthesis, leaves
give off oxygen and
H2O.
Middle
school
students
think of
feces. It is
an
example.
Kidneys filter waste
from blood. It is
eliminated as urine.
Legume plants
have “nodules” for
bacteria to live.
Some waste from
bacteria is
Nitrogen in a form
that plants and
animals need.
Living Things Grow and Mature
Living Versus Non-Living
Living things will have all of the six
characteristics (at some time).
NON-living things may have “some” of
these characteristics, but NOT all.