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Biology is defined as
“the study of the
living world”.
One of the most
important base
concepts of biology
is deciding what is
living, and what is
not.
Biologists agree that something is alive if
it shows several common traits. Anything
that is alive is called an organism.
 All living organisms have all of these
traits. There may be things that show
some of these traits, but they are NOT
alive, because they do not show all
those traits.
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If something is alive,
it is made up of cells.
Cells are considered
the smallest living
units of matter.
Unicellular
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Multicellular
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Unicellular organisms are made up of only
ONE cell.
“Uni-” means one
Multicellular organisms are made up of
MORE than one cell.
“Multi-” means many or several
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All living organisms
can reproduce.
This means that living
organisms can
create new
organisms.
Asexual Reproduction
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Sexual Reproduction
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Asexual reproduction only requires ONE
parent.
Includes fission and budding.
Sexual reproduction requires TWO
parents.
Two different cells combine to form a new
organism.
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All living organisms
use a genetic code.
This code is the
reason why many
traits can be
inherited, or passed
on.
All living organisms grow.
 Many multicellular organisms develop
special tissues.
 However, unicellular organisms do NOT
exhibit development.
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All living organisms
require materials
and energy.
This is because both
materials and
energy are required
for growth and
development!

Metabolism: the
building or breaking
of materials to
support life.
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All living organisms
can sense and
respond to changes
in the environment.
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These changes are
called stimuli.
Stimuli can be
external or internal.
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Living organisms
have to maintain
internal conditions to
live.
We call these
conditions
homeostasis.
Homeostasis is the state of balance that
an organism can exist at.
 For instance, we must maintain our water
content to live.
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› Too much or too little water and we die!
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We also have to maintain our internal
temperature, or we will die!