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Energy Pathway
Energy importance
• Most of your life is
involved with energy
whether you realize it or
not.
• Energy is the cause of
many wars.
• Energy is why you eat,
sleep, go to school, and
work.
• Energy powers your
lights, cell phones, ipods,
computers, TVs, cars,
etc… but….
Energy importance
• … energy is also what
powers your body and
your brain.
Energy importance
• So, where does all this
energy come from, how
do we use it, and where
does it go from here?
• That is what we will be
learning about during
this unit.
Types of energy
• Types of energy you
might have heard of so
far this year include:
–
–
–
–
–
Kinetic
Potential
Heat
Light
Sound
Types of energy
• This unit we will be
discussing these types
of energy:
– Light energy
– Chemical energy
• (chemical potential or
food energy)
– Mechanical energy
– Heat energy
The Sun – Energy’s beginning
• The energy you use to
power your body
originally came from
the sun (the big yellow
one.)
The Sun – Energy’s beginning
• The sun makes energy by
doing nuclear reactions in
its core.
• In the core of the sun,
Hydrogen atoms are
being smashed together
under high temperature
and pressure to form
helium atoms.
• This nuclear reaction
releases huge amounts of
energy (more energy than
a billion hydrogen bombs
per second.)
The Sun – Energy’s beginning
• Electromagnetic energy
leaves the sun in the
form of heat and light.
• It takes about 8 minutes
and 20 seconds for this
heat and light energy to
travel to earth. (It
would take you 21 years
to travel to the sun in a
jet.)
From light energy to chemical energy
• We can not use light or
heat energy to power
our body, but…
• Some organisms are
able to use the sun’s
light energy to make
food.
• Food energy is also
called Chemical energy
or chemical potential
energy.
From light energy to chemical energy
• Organisms that can
convert light energy
into chemical energy
are called producers.
• Almost all plants are
producers (>99%).
• Photosynthesis is when
producers make their
own food using light
energy from the sun.
Pine drops
From light energy to chemical energy
• Photosynthesis occurs
in the chloroplasts of
plant or algae cells.
• Chloroplasts have a
green pigment called
chlorophyll in them
that is able to transform
light energy into
chemical energy. (In
the form of sugars or
starches.)
From light energy to chemical energy
• Organisms that can make
their own food (Producers)
are also called autotrophs.
• “Auto” = self
• “troph” = nutrition (food)
– If they use the sun to make
their own food (as most
producers do,) they could be
called photoautotrophs. (As
opposed to
chemoautotrophs.)
Review so far…
• So, producers, which are also
called autotrophs, convert the
light energy from the sun into
chemical energy in the form of
sugars.
• The reaction looks like this:
– 6CO2 + 6 H2O  C6H12O6 + 6O2
Eating sunlight!
• So, when you bite into a
piece of lettuce, its like
biting the light of the
sun!
Importance of photosynthesis
• Most of the material that makes
up the plant is made by the
plant using the process of
photosynthesis.
• All of the oxygen that we
breathe each day comes from
the process of photosynthesis.
• Almost all of the energy that
powers your body came from
the process of photosynthesis.
Respiration
• So, how does the
chemical energy made
in plants become energy
that powers your body?
• Respiration is the
process of changing
chemical energy stored
in food into usable
chemical energy that
can be used to power
your body.
From stored chemical energy to
usable chemical energy
• Respiration occurs in the
mitochondria of cells.
• Sugar (from digestion) and
oxygen, (from breathing)
combine to form carbon
dioxide gas, water, and ATP.
• ATP is usable chemical
energy.
– Like a full battery for your
body.
Respiration
• The formula for respiration looks like this:
– 6O2+ C6H12O6 6CO2 + 6 H2O + ATP (Usable chemical energy)
From usable chemical energy to
mechanical energy
• ATP is used to power your
muscles, your brain, your
heart, and every other part
of your body.
• When ATP is converted to
ADP, the chemical energy
stored in the ATP can be
converted into mechanical
energy, which is a
combination of kinetic and
potential energy.
From usable chemical energy to
mechanical energy + heat
• When the chemical energy
is converted into
mechanical energy, there is
a lot of heat energy that is
also produced.
• Some of this heat energy is
used to maintain body
temperature, but most is
lost to the environment.
(About 60% of the energy is
lost in the form of heat.)
Consumers
• Organisms that can’t do
photosynthesis, and
have to get their
chemical energy by
feeding on other
organisms are called
consumers.
Consumers
• Consumers are also called
heterotrophs.
• “Hetero” = different
• “Troph” = food
• Heterotrophs (consumers) can
get their energy by feeding on
producers (herbivores), by
feeding on other heterotrophs
(carnivores), or both
(omnivores).
So, the whole pathway looks like
this…
ATP
Quiz: What type of energy is this?
Quiz: What type of energy is this?
Quiz: What type of energy is this?
Quiz: What type of energy is this?