Transcript Energy - Mayfield City Schools

Chapter 03
Lecture Outline*
William P. Cunningham
University of Minnesota
Mary Ann Cunningham
Vassar College
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Matter, Energy, and Life
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Outline
• Elements of Life
• Organic Compounds and Cells
• Energy
– Laws of Thermodynamics
– Photosynthesis/Respiration
• Ecosystems
– Food Chains
– Ecological Pyramids
– Material Cycles
3
3.1 Introduction
• Ecology is the scientific study of the relationship
between organisms and their environment
• Questions how matter and energy are exchanged
between organisms and their surroundings
4
Elements of Life
• Matter: everything that has mass and takes up space
Solid - Liquid - Gas = 3 states of matter
• Matter is neither created nor destroyed but rather
recycled over and over
• The idea that matter cannot be destroyed but is
simply transformed from one form to another is
termed conservation of matter
5
Elements
• Matter consists of elements.
• Elements - substances that cannot be broken down into
simpler forms by ordinary chemical reactions
– 118 elements
– Four (oxygen, carbon, hydrogen and nitrogen) make
up 96% of the mass of living organisms
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• All elements are composed of atoms
• Atoms - smallest particles exhibiting characteristics of
the element
• Atoms are composed of:
– Protons (+) - Neutrons - Electrons (-)
– Protons and neutrons are in the nucleus; electrons
orbit.
– Atomic Number: Number of protons
– Isotope - forms of an element differing in atomic
mass due to the fact that the isotopes have different
numbers of neutrons
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Chemical Bonds
• Compound - substance composed of different
kinds of atoms
– Molecule: two or more atoms joined together
– Chemical Bond - forces (chemical energy) holding
atoms together in molecules
• Ionic - Atoms with opposite charges (ions) form a
bond e.g. Na+ and Cl- .
• Covalent - atoms share electrons (but not always
equally)
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Common Molecules
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Oxidation and Reduction
• When an atom gives up one or more electrons, it is
oxidized
• When an atom gains electrons, it is reduced
• Oxidation and reduction are an important part of
how organisms gain energy from food
• Forming bonds uses energy; breaking bonds
releases energy.
• Activation energy is often needed to begin a reaction
(e.g. match needed to start a fire)
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Ions, Acids, and Bases
• Ions - atoms that contain more or fewer electrons than
protons and therefore have a positive or negative charge
– Anions have a negative charge
– Cations have a positive charge
• Acids - substances that release hydrogen ions in water
• Bases - substances that readily bond with hydrogen ions
– pH scale: logarithmic; each step is 10X
– 0 to 7 is acidic / 7 is neutral / 8 to 14 is basic
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pH Scale
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Organic Compounds
• Organic Compounds - Material
making up biomolecules, which
in turn make up living things. All
organic compounds contain
carbon.
• Four major categories of organic
compounds:
• Lipids
• Carbohydrates
• Proteins
• Nucleic Acids
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Cells
• Cells - minute compartments in a living organism
which carry out processes of life
– Surrounded by lipid membrane controlling flow of
materials in and out of cell
– Interior may be sub-divided into organelles and
sub-cellular particles.
• Enzymes - Molecular catalysts regulating chemical
reactions. Enzymes are usually proteins.
• Metabolism - multitude of enzymatic reactions
performed by an organism
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3.2 Energy
• Energy - ability to do work
– Kinetic - energy in moving objects
• Ex: wind blowing, water flowing
– Potential - stored energy
• Ex: Water behind a dam
• Chemical - stored in the bonds of chemical
molecules
–Ex: food or fossil fuels
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3.2 Energy
• Energy is measured in calories, BTUs (British Thermal
Units), or Joules
• Power – the rate of doing work (watts)
• Heat – a measure of total energy of a substance transfer of energy between two objects due to
temperature differences
• Temperature – a measure of the speed of motion of a
typical atom or molecule in a substance
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Thermodynamics
• THERMODYNAMICS deals wi
th how energy is transferred
in natural processes
• First Law of
Thermodynamics:
energy is neither created n
or destroyed.
• It may be transferred.
(one place to another
• It may be transformed.
(one form to another)
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Thermodynamics
• Second Law of Thermodynamics - With each successive
energy transfer, less energy is available to perform work
• Energy is not lost.
• It has been degraded from a higher
quality form to a lower quality form such as heat.
• Natural systems go from a state of order
to a state of disorder
• Entropy – amount of disorder. This increases
as energy is transferred.
• Example: A burning fire produces heat.
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3.3 Energy for Life
• Solar energy is essential for 2
reasons:
• Warmth (due to solar radiation)
• Most organisms can exist only in
a relatively narrow temperature r
ange.
• Photosynthesis- process
whereby the sun’s radiant
energy is converted to high
quality chemical energy in the
bonds which hold together
organic molecules (glucose)
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• Ultimately, most organisms depend
on the sun for the energy needed to
carry out life processes
• Exception: a few very ancient
organisms called archaea are able to
get their energy from inorganic
compounds (hydrogen sulfide) –
chemosynthesis
– bubble up from vents in the sea floor or
from hot springs
– methane generated by these undersea
communities could be a source of
natural gas for us
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Solar Energy
• Of all solar radiation reaching
the earth’s surface, about 10%
is ultraviolet, 45% is visible,
and 45% is infrared.
– Most energy is absorbed by
land or water, or reflected
back into space
• Only about 1-2% of the
sunlight falling on plants
is captured for
photosynthesis
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Solar Energy
• Only light in the visible
spectrum
can be used for
photosynthesis.
• Only about 1-2% of
the sunlight falling on
plants is captured for
photosynthesis
23
Process of Photosynthesis
• This requires chlorophyll, a green molecule found in t
he chloroplasts of plant cells, which can absorb light
energy.
• The process of photosynthesis involves two intercon
nected cyclic sets of reactions.
• Light‐dependent reactions: Occur while light is being
received by the chloroplast
– Water molecules are split.
– Oxygen is released.
– This is the source of all the oxygen in the atmosphere.
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Process of Photosynthesis
• Light‐independent reactions:
occur in the chloroplast
without the need for light (AKA
dark reactions
• Enzymes use energy captured
from light to add a carbon
atom (from carbon dioxide) to
form a small sugar molecule
• The result is a molecule of glu
cose (sugar)
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26
Overall Reaction for Photosynthesis
• 6H20 + 6CO2 + solar energy
• Water and carbon dioxide in
the presence of sunlight and
chlorophyll (the green
pigment in chloroplasts)
yield glucose (sugar) and
oxygen
• Glucose - primary fuel for all
metabolic processes
C6H12O6 + 6O2
– Energy in chemical bonds used to make other molecules
(proteins) or it can drive
movement, transport, etc.
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Cellular Respiration
• Cellular Respiration: process
by which glucose (or some
other molecule) is broken
down, releasing its energy
– This involves glycolysis
(splitting glucose) and the
Kreb’s cycle.
– How animals get all their
energy
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Overall Reaction for Cellular
Respiration
• C6H12O6 + 6O2
6H2O + 6CO2 + energy
• Together, photosynthesis and cellular respiration
create a cycle.
29
Energy Exchange in Ecosystems
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3.4 From Species to Ecosystems
• Species - all organisms of the
same kind that are genetically
similar enough to breed in
nature and produce live,
fertile offspring
• Population - all members of a
species living in a given area at
the same time
31
From Species to Ecosystems
• Biological Community all of the populations of
organisms living and
interacting in a particular
area
• Ecosystem - biological
community and its
physical environment (air,
water, soil, minerals,
sunlight)
– The boundaries of an
ecosystem are not easy to
define.
32
Ecosystems
• We often define an
ecosystem as the area we
wish to study.
– Ex: forest, pond, field, etc.
• Most ecosystems are open in
the sense that they exchange
materials and organisms with
other ecosystems.
• With regard to energy, every
ecosystem is open because it
must constantly be supplied
to it.
33
Food Chains, Food Webs, and
Trophic Levels
• Productivity - the amount of
biomass (biological matter)
produced in a given area in a
given period of time
– Example: kilograms/ meter2/ year, or
kilograms/hectare/year
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Productivity
• Primary Productivity –
biomass produced by
plants through
photosynthesis
• This depends on factors
such as water, sunlight,
minerals, soil, etc.
• Tropical rain forest very
productive
• Desert not very
productive
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Productivity
• Secondary Productivity –
biomass produced by
animals which eat plants
36
Food Chains
• Food Chain – the sequence
of organisms through which
energy is transferred from
one trophic level (feeding
level) to another
• A food chain begins with a
producer (plants, algae)
which transforms solar
energy into chemical energy
• Consumer – makes use of the
energy captured by plants
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Consumers
• Primary consumer –
(Herbivore) organism
which eats plants
• Secondary consumer –
(Carnivore) organism
which eats animals
(includes eating insects,
worms, etc)
• Tertiary consumer – (Top
Carnivore) a carnivore
which eats another
carnivore
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Consumers
• Omnivore – an organism
which eats either plants
or animal material
– Ex: humans
• Scavenger – an organism
which feeds on the dead
carcasses of animals
– Ex: crows, jackals,
vultures
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Consumers
• Detritivore– an organism which
consumes litter, debris, and dung
which collectively are known as
detritus
– Ex: ants, beetles
• Decomposer– an organism which
completes the final breakdown
and recycling of organic matter
– Ex: fungi, bacteria
– Extremely important because
they recycle nutrients which
are locked up in organic
compounds of dead organisms
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41
Food Chain
42
Food Webs
• Food Web – a
series of
interconnected
food chains. The
more complex the
food web, the
more stable the
ecosystem
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Ecological Pyramids
44
Ecological Pyramids
• This pyramid arrangement is
especially true if we look at the
energy content of and ecosystem
• Reason due to 2nd Law of
Thermodynamics
– Some energy is lost at each level
in the daily process of living
– Some energy is lost as heat.
• In general, only 10% of the energy in
one consumer level is represented in
the next higher level. Known as
10% Rule (energy/biomass)
– Example: 100 kg of clover
needed to make 10 kg of rabbit
which can make 1 kg of fox.
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Biomass Pyramid
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Energy Pyramid
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3.5 Material Cycles
• Hydrologic Cycle - path of water through the environment
– Solar energy continually evaporates water stored in the
oceans and land, and distributes water vapor around
the globe
– Water vapor condenses over land surfaces, supporting
all terrestrial systems
– Precipitation falls to the earth – absorbed into the
ground or runs off into rivers/bodies of water
– Plants lose water from their surfaces as vapor during
transpiration
– Responsible for cellular metabolism, nutrient flow in
ecosystems, and global distribution of heat and energy
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Hydrologic Cycle
49
Carbon Cycle
• Functions of Carbon
– Structural component of all organic molecules
– Molecules which contain carbon are used to store energy
(ex: glucose, starch, fat)
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Carbon Cycle
• In the carbon cycle, CO2 is taken in by plants during the
process of photosynthesis and carbon is incorporated into
molecules of glucose.
• Cellular respiration breaks down glucose and releases
carbon in the form of CO2.
51
Carbon Cycle
• Carbon may be recycled
quickly or it may be
incorporated into the
organism and may remain
for a very long period of
time
(wood in a very old tree)
• Plants are a major reservoir
(sink) for carbon.
• Over millions of years,
buried deposits of plant
matter and bacteria are
compressed to form carbon
containing fossil fuels.
52
Carbon Cycle
• In the oceans, carbon is locked
up as calcium carbonate
(CaCO3), used to build shells
and skeletons of marine
organisms (protozoans, coral)
• When the organisms die, their
shells or skeletons are deposite
d in ocean sediment. Pressure
causes the formation of
limestone.
53
Carbon Cycle
• Carbon may remain in the
form of limestone for millions
of years
• Eventually, these deposits are
drawn into molten layers
under the ocean and released
via volcanic activity.
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Human Impact on Carbon Cycle
• Cutting down trees and
plants which absorb CO2
through photosynthesis
• Releasing more CO2 by
burning fossil fuels and
wood
• Excess CO2 in the
atmosphere could
contribute to the
greenhouse effect,
resulting in global
warming
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Carbon Cycle
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Nitrogen Cycle
• Nitrogen is crucial for all
living organisms because
it is an essential part of
biological molecules
such as proteins, amino
acids, and nucleic
acids(DNA, RNA).
• The atmosphere is 78%
nitrogen but this
cannot be used directly
by most organisms.
•
https://www.youtube.com/watch?v=leHy-Y_8nRs
57
Nitrogen Cycle
58
Nitrogen Cycle
• Nitrogen Fixation: the conversion of
gaseous nitrogen (N2) to ammonia
(NH3).
• Some ammonia then reacts with H2O to
form ammonium (NH4+)
• “Fixing refers to putting nitrogen into
a more useable form
• Combustion, volcanic activity,
lightning, and industrial processes
can “fix” nitrogen, forming ammonia
• Nitrogen‐fixing bacteria (cyanobacteria)
– carry out nitrogen fixation in the soil
and water
• Some nitrogen fixing bacteria
Rhizobium) live inside swellings
called nodules on the roots of
legumes (beans, peas)
• This is an example of
mutualism
(both organisms
benefit)
• The bacteria get
carbohydrates
and the plants get
nitrogen in a
form they can use
59
Nitrogen Cycle
• Nitrification the conversion of NH3 or
NH4+ to nitrate(NO3‐) by bacteria
living in the soil
• This is a two‐step process:
• Nitrite-forming bacteria
combine ammonia with
oxygen to form nitrites(NO2‐), which are toxic.
• Nitrate-forming bacteria convert
nitrites to nitrates (NO3‐) which can
be absorbed and used by plants.
• Assimilation–the
conversion of inorganic nitrogen (nitrates,
ammonia) to organic molecules
(amino acids, proteins) inside living
organisms
• Ammonification- (opposite of assimilation)
the breakdown of organic molecules
containing nitrogen into ammonia
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Nitrogen Cycle
• Waste (urea) is broken down.
• Plant materials such as
leaves, fruits, flowers are
broken down
• This process is carried out
by ammonifying bacteria
in the soil and water.
• The ammonia produced
in this way is recycled
back to the nitrogen cycle
and is again available for
nitrification
and assimilation.
61
Nitrogen Cycle
• Denitrification:
the reduction of NO3
to gaseous nitrogen
(N2)
• This process is carried
out by denitrifying
bacteria
• These live in areas with
little free oxygen (deep
in the soil near the
water table)
62
Human Impact Nitrogen Cycle
• Synthetic fertilizers, cultivating
nitrogen- fixing crops and
burning fossil fuels all convert
nitrogen to ammonia and
nitrates at a greater
rate than all land processes
• Increase in nitrates leads to:
• loss of calcium & potassium from
the soil
• acidification of lakes and rivers
• rising levels of nitrous oxide
(a greenhouse gas)
• introduction of weeds & algae
(eutrophication)
63
Phosphorous Cycle
• Phosphorus is necessary
for energy-transfer
reactions in cells. (ATP
adenosine triphosphate).
Used in production of
DNA/RNA
• The phosphorus cycle begins
when phosphorus is leached
form rocks and minerals over
long periods of time
• Phosphorus is
transported by water, not
in the air.
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Phosphorous Cycle
• It is taken up by producers
and passed on to consumers
• Decomposers return it to the
environment
• Deep sediments of the oceans are
sinks for significant amounts
of phosphorus.
• Cycling takes a long time.
• Human production of phosphate
detergents and fertilizers has
stimulated the growth of algae in
water (algal bloom)
65
Sulfur Cycle
• Sulfur is an essential
component of proteins.
• Most sulfur is in rocks and
minerals.
• Sulfur is released into the
air by weathering,
emissions from seafloor
vents, and volcanic
eruptions.
66
Sulfur Cycle
• Human activities
release sulfur dioxide
(SO2) by burning
fossil fuels.
• SO2 combines with
water to produce
sulfuric acid (acid
rain).
67
Sulfur Cycle
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