Transcript ch 3 CP biomes energyflow and matter cycles

ENERGY FLOW AND
MATTER CYCLES
CHAPTER 3
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What do you think of when you
hear the word “energy”?
Some terms we will use are:
Chemical, mechanical, stored, electrical…
Efficiency
Solar, nuclear, wind
Primary, secondary consumers
Energy pyramid
Food webs and chain
Energy cannot be created or destroyed, but
it can change from one form to another.
No energy conversion is 100%. Some energy
is always lost.
3.1 Energy Flow In Nature And
Human-built Systems
Where Do Most Organisms
Get Their Energy?
 The sun!
 Plants, algae and some kinds of bacteria
capture the sun light and produce sugar, an
energy rich food.
 This process is called photosynthesis.
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6CO2 + 6H20 +
→ C6H12O6 + 6O2
• Producer (autotroph)- an
organism that gets its energy
from the sun. Examples are
grass, clover, trees
• Consumer (heterotroph)- organisms that eat
other organisms. Examples are rabbits, lions
and spiders
• Consumers get their energy indirectly from
the sun by eating producers or other
organisms that eat producers.
Types Of Consumers
• Herbivores- eat only producers such as
cows, sheep, deer and grasshoppers
• Carnivores- eat only other consumers such
as hawks and lions
• Omnivores- eat both plants and animals
such as humans, pigs and bears
• Scavengers – eat remains of dead animals
such as vultures and hyenas.
• Decomposers- get their food by breaking
down dead organisms such as bacteria and
fungi
What is Cellular Respiration?
It is the process of breaking down food to
get energy.
C6H12O6+ 6O2 → 6CO2 +6H20 + energy
Is an
aerobic
process
Energy Transfer
• Each time an organism eats another,
a transfer of energy occurs.
• We use food chains, food webs and
trophic levels to follow the flow of
food energy.
• Trophic= feeding level
Food Chains
A simple representation of how energy
is transferred.
Food Webs
Is a more accurate representation of
what is really happening when
organisms eat.
Energy Pyramids
• Each layer is a trophic (feeding) layer
• Producers form the base level
• Heterotrophs make up the second level and
carnivores are on the rest of the levels
• As you go up the side of the
pyramid, the amount of
energy decreases and the
number of organisms also
decreases.
How Does Energy Loss Affect an
Ecosystem?
1. There are fewer organisms at the
higher trophic levels.
2. The loss of energy to each trophic
level limits the number of levels in an
ecosystem.
3. There are usually no more than 4-5
levels because there is not enough
energy left to support higher trophic
levels.
This is an energy pyramidNotice there is a 90% loss of energy as you
go up the pyramid. Only 10% of energy is
available for the next level.
3.2 Resource Recycling In Nature:
The Biogeochemical Cycles
There are 4 major cycles:
• Hydrologic (water)
• Mineral/nutrient
• Carbon
• Nitrogen
The Water Cycle
Mineral/Nutrient Cycle
• Includes all the nutrients needed by
organisms.
• Minerals originate in rocks and are
released when rocks weather.
• Eventually these minerals end up in
the water and soil.
The Carbon Cycle
The Carbon Cycle
• A key element in organic molecules.
• Plants take in CO2 during photosynthesis and
all organisms release it during respiration
(returned to the air).
• Stored as a carbohydrate (C6H12O6)
• Returned to air when organisms die and
decompose.
• Can be stored for long periods of time in
waters, plants, shells and skeletons of marine
organisms (CaCO3)
The Carbon Cycle
• Carbon is stored in fossil fuels and
released when they burn.
• Fossil fuels = oil, coal, natural gas, oil
shale, tar sands
• CO2 is a greenhouse gas and is believed
to contribute to global warming.
• Carbon sinks= ocean and forests
Nitrogen Cycle
Nitrogen Cycle
 Organisms need nitrogen to make proteins.
 Nitrogen gas (N2) makes up 78% of the atmosphere.
 Plants need nitrogen to grow, but cannot use it directly
from the atmosphere.
 Nitrogen-fixing bacteria convert the N2 into a useable
form. This is called nitrogen fixation.
 Some plants have nitrogen-fixing bacteria in nodules on
their roots which house the bacteria- a mutualistic
relationship. These plants are legumes such as peas, soy
beans and alfalfa.
 Other bacteria live in the soil and add the nitrogen to
the soil.
Nodules On The Roots Of A Legume
Nitrogen Cycle
• How does nitrogen get “fixed”?
• Atmospheric nitrogen is converted by bacteria
into ammonia (NH3). Ammonia is then
converted into nitrite and then nitrate by
nitrifying bacteria. Plants then take in the
fixed nitrogen.
• Animals get their needed nitrogen by eating
plants.
• Not a lot of nitrogen in the soil, so it is added
to the soil as animal manure and fertilizer.
3.3 Matter And Energy
3.4 Kinetic And Potential Energy
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Mass, matter and energy
Potential and kinetic energy
Identify the type of energy in each situation.
Burning candle
Kinetic
Tree growing
Kinetic
Gallon of gasoline
Potential
Rock balanced on a cliff
potential
3.5 Closed and Open Systems
• All cycling occurs in a system.
• A system is a designated area, space
or region under study.
• Earth is a closed system as far as
matter goes.
• Earth is an open system as far as
energy goes.
Closed and Open Systems
• Closed system: nothing enters or leaves.
Everything is used and reused.
• Open system: things both enter and leave.
• Steady state: properties are constant because
substances enter and leave at the same rate.
• Using figure 3.15, answer question 1 on page
85.
3.6 Conservation Laws
• Law Of Conservation Of Matter – total
mass on earth is constant.
• Law of Conservation of Energy- energy
cannot be created or destroyed. It can,
however, be transformed from one form to
another ( mechanical → heat i.e. rubbing
hands together ).
• This law is also known as the First Law Of
Thermodynamics.
Why are these laws important in
environmental science?
• Think about recycling, mining, garbage,
pollution and food chains.
• As a group, discuss the questions on page 86.
3.7 Forms Of Energy
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Mechanical
Heat (thermal)
Radiant (including light)
Electrical
Chemical
Nuclear
Identify The Form Of Energy
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Food Cooked In A Microwave
Radiant
Light From A Light Bulb
Electrical
Energy Stored In Bonds
Chemical
Electromagnetic Waves
Radiant
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Moving cars
Mechanical
Burning wood
Chemical, light and heat
Fusion and fission
Nuclear
Photosynthesis
Chemical
3.8 Energy Sources
• The Sun
– Energy drives the
winds, waves, and
climate.
– Provides energy for
photosynthesis.
– Fuels all life processes!
– Only 0.1% of sun’s
radiation reaches
Earth, and only 70% of that reaches the
atmosphere and surface.
– Solar energy is stored in living plants. These plants
can form oil, coal, natural gas, oil shale, tar sands .
More Energy Sources
• Tides
• Earth’s Heat
– Geothermal energy
• Fission Fuels
– Energy stored in unstable uranium and thorium
nuclei
– Nuclear energy
• Fusion Fuels
– Involves combining small nuclei into larger
nuclei. By combining nuclei (deuterium and
tritium), energy is released. (the sun)
3.10 The 3 Forms of the
Second Law of Thermodynamics
• 1. In any transformation of energy from one
form to another, there is always a decrease in
the amount of useful energy.
• 2. Heat cannot, by itself, flow from cold to hot. It
spontaneously flows from hot to cold.
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http://www.youtube.com/watch?feature=fvwrel&v=C0NBosKaznA&NR=1
• 3. In any closed system, disorder has a natural
tendency to increase. (chaos, randomness,
entropy)
Special Focus:
The Kinetic Theory Of Matter
The kinetic theory is based on 3 assumptions.
• 1. All matter is made of atoms, molecules or
ions.
• 2. Atoms, molecules and ions are in constant
motion. The greater the motion of the
particles, the warmer the object.
• 3. Moving particles do not lose energy when
they collide with each other or with a rigid
container.
3.11 Energy and Efficiency
• Efficiency = useful energy or work x 100%
energy or work in
OR
• Efficiency = work output x 100%
work input
Determine the efficiency of …
• A device in which the energy input is 100 calories
and the output is 30 calories.
30 cal x 100 = 30%
100 cal
• A device in which 10 Btu of energy were produced
from an original 250 Btu. (Btu is an energy unit,
most often used with heating and air systems)
10 Btu x 100 = 4%
250 Btu
No Efficiency Can Be
Greater Than 100%
• You can’t get more work out of any process
than what you put in.
• Energy is often lost to friction (heat) so
industry tries to reduce friction by using
lubricants, making machines smooth….
• Heat engines and lighting are very inefficient.
3.12 System Efficiency
• See figures 3.39 and 3.40
• Study figures 3.41 and 3.42
• Complete the Questions/Tasks on pages 112
and 113 of your text.
3.13 Net Energy and
3.14 Energy Quality
• Net Energy - Ratio of total energy produced over
the lifetime of the system to the total energy,
direct and indirect, used to produce that energy.
• Energy Quality – how useful is the energy?
High quality energy can be used to move
things or generate electricity. It is organized and
concentrated.
Ambient temperature heat is low quality. It
is heat at a temperature near that of the
surroundings. It cannot be used to produce
mechanical or electrical energy.
Developed Countries Are
Energy Dependent
• Therefore, energy quality is important.
• Most activities result in matter becoming more
disorganized and as energy is transformed, it
goes to less useful forms. Our energy supply is
continuously losing its ability to move objects
and produce electricity.
• What can be done to improve our use of energy?
• http://www.youtube.com/watch?v=HOQSAjc3
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