BIOLOGY
What exactly is biology anyway?
Biology has to do with…..
 Living things, of course!!
 Don’t forget things that are not alive (nonliving)!
 What about things too small to see
(microscopic)?
 And how about the major processes that tie
all of these things together (biological
cycles)?
 The word biology comes from two greek
words put together.
– “bios” – meaning “life”
– “logos” – meaning “thought or study of”
 Biology is the branch of science that deals
with the study of living things. This also
must include how these living things interact
with the non-living world around them.
The age-old question: What is the
meaning of life?
 How do we know if something is alive or not
alive?
 What does it actually do to be alive?
 Consider the following…
 Is there a difference between these two
pictures in the quality of “life”??
 Obviously!
 Take this plant, squirrel and rock for
example.
 Why is the plant and squirrel alive and the
rock is not?
 Specifically what can the plant and squirrel
do that the rock cannot?
Characteristics of all living things
Each individual living thing is called an organism.
All organisms have the following characteristics:
 The need for energy.
 Limited life span.
 Highly organized and contains complex chemical
substances.
 Growth.
 Reproduction.
 Will respond to changes in the environment.
 Ability to change and adapt to surroundings.
1) The need for energy
 All living things need
energy. Anything that
is alive requires a
continuous supply of
energy to support their
bodily functions.
Almost all the energy
used by a living thing
comes from the sun.
 Plants store the energy from the sun as
glucose (sugar) in their leaves in a process
called photosynthesis. The plant uses this
sugar as food to support the rest of its
functions.
 Animals receive their
energy from the foods
they eat. During
digestion, the food is
broken down into
glucose (sugar) which
is stored in the cells of
the body and is burned
when needed to fuel
activities.
2) Limited Life Span
 If something is alive it will eventually die.
The life span of organisms can vary greatly.
– Example: The mayfly lives for only a few hours
to a few days, whereas the giant tortoise lives
for about 177 years (in captivity)
3) Highly Organized and Contain
Complex Chemical Substances
 All living things are made up of one or more
cells.
 The cell is the smallest, most basic unit in
which substances are organized to produce
a living thing.
 The presence of cells
does not guarantee
life exists. After the
death of an animal,
the cells are present
but are not
functioning so it is not
alive. But the
presence of cells
does show that life
did exist at one point
in time.
 Living cells contain a complex mixture of
substances called protoplasm. All of the
components that make up protoplasm are
not alive by themselves, yet the cell has the
ability to organize all parts of the protoplasm
to be alive.
 Since living things have the ability to
organize substances they are called
“organisms”.
4) Growth
 All living things grow at some point in their lifetime
but each species grows at different rates.
– Bacteria have a very small growth in size.
– Some trees species can grow very large in size.
 Non-living things can also appear to grow.
– Salt or sugar crystals in an evaporating dish
– Icicles on the roof in winter
 One important difference between growth of
living things from non-living is how the
growth happens.
– Living things grow from the inside out
– Non-living things grow by adding more to the
outside (like snowmen!)
Growth Continued
 Maintenance and repair is a type of growth
where the organism does not necessarily grow
any larger but must constantly maintain and
repair the materials of which they are made.
– Shedding of skin cells
– Cut on finger
– Salamander’s tail
5) Reproduction
 Living things can produce offspring similar to
themselves. (Biogenesis)
 Since the lifespan of a living thing is short,
they go through phases: growth  maturity
 reproduction  latency  death. They
must be able to create new life to replace
them when they are gone.
6) Response to stimuli
 All living things respond to stimuli, or changes in
their environment/ surroundings. A stimulus can
be sound, touch, heat, light, moisture etc.. Which
causes a response from a living thing.
 A living thing’s response to a stimulus is called
irritability.
–
–
–
–
Obtain food (animals, carnivorous plants)
Avoid predators (animals)
Turn towards light (plants)
Gravity (plant root growth)
7) Variation and adaptation
 In addition to irritability (short term response
to a stimulus), living things respond to long
term changes over many years.
 Organisms may be poorly suited to surviving
changes in soil type, moisture, temperature
so they change to become better at
surviving in the new conditions.
 These changes are a result of variation.
 The differences between parents and
offspring are the result of variation. Some
variations do not affect the survival of an
organism or species. Where the difference
or variation is crucial to the survival of the
organism, the change is called an
adaptation.