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1
Chapter Two: Principles of
Ecology: Matter, Energy and Life
from your text, Principles of Environmental
Science: Inquiry and Applications, 2nd ed.
William and Mary Ann Cunningham. (New York:
McGraw-Hill, 2003)
2
Required Reading
Chapter Two: "Principles of Ecology: Matter,
Energy, and Life.” from your text, Principles of
Environmental Science: Inquiry and
Applications. 2nd ed. William and Mary Ann
Cunningham. (New York: McGraw-Hill, 2003)
.
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Chapter Two Objectives
Objectives
At the end of this lesson, you should be able to
•
describe matter, atoms, and molecules;
•
list the four major kinds of organic compounds in cells; give simple examples of their roles
•
define energy, and explain the difference between kinetic and potential energy;
•
explain the principles of conservation of matter and energy and describe how the laws of
thermodynamics affect living systems;
•
explain how photosynthesis captures energy for life and how cellular respiration releases that
energy to do useful work in a cell;
•
define species, populations, biological communities, and ecosystems, and understand the
ecological significance of these levels of organization;
•
discuss food chains, food webs, and trophic levels in biological communities, and explain why
there are pyramids of energy, biomass, and numbers of individuals in the trophic levels of an
ecosystem; and
•
explain the importance of material cycles, such as carbon and nitrogen cycles, in ecosystems.
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Chapter Two Key Terms
McGraw-Hill Course Glossary
 Acids
 Ecosystem
 Organic compounds
 Atom
 Energy
 pH
 Bases
 First law of
thermodynamics
 Photosynthesis
 Biological community
 Biomass
 Carbon cycle
 Carnivores
 Cellular respiration
 Compound
 Conservation of matter
 Consumers
 Decomposer
 Ecology
 Food web
 Herbivores
 Ions
 Kinetic energy
 Matter
 Metabolism
 Potential energy
 Primary producers
 Productivity
 Second law of thermodynamics
 Species
 Tropic level
 Molecules
 Nitrogen cycle
 Omnivores
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Chapter Two - Topics
• Energy and Matter in the Environment
• Organizing Living Things: Species and
Ecosystems
• Biochemical Cycles and Life Processes
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Part 1: Energy and Matter in
the Environment
To understand how ecosystems function, it is
important to first know something about how
energy and matter behave - in the universe and
in living things. It is also important to
understand the basic building blocks of life,
starting with cells and organisms, and
proceeding to communities and populations.
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Interrelated Scientific Principles:
Matter, Energy and Environment
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Ecology
• The scientific study of relationships between
organisms and their environment
• Examines the life histories, distribution, and behavior
of individual species, as well as the structure and
function of natural systems at the level of
populations, communities, ecosystems, and
landscapes
• Encourages us to think holistically about
interconnections that make whole systems more
than just the sum of their individual parts
• Examines how and why materials cycle between the
living and nonliving parts of our environment
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Matter and Energy
• Matter and energy are essential
constituents of both the universe and
living organisms.
• Matter - everything that takes up space
and has mass
• Energy - the capacity to do work
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Potential vs. Kinetic Energy
• Potential energy - stored energy that is latent but
available for use
• Kinetic energy - the energy contained in moving
object
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Heat and Temperature
Heat - describes the total kinetic energy of atoms or
molecules in a substance not associated with bulk motion of
the substance
Temperature - a measure of the speed of motion of a typical
atom or molecule in substance
Heat and temperature are not the same. A substance can
have a low temperature (low average molecular speed) but a
high heat content (much mass and many moving molecules
or atoms). For example, a lake might feel cold to your hand,
but it contains an immense amount of stored heat.
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Energy Quality
Low Quality Energy
• Diffused, dispersed, or low in temperature
• Difficult to gather and use for productive purposes
• Example: heat stored in the oceans
High Quality Energy
• Intense, concentrated, or high in temperature
• Useful in carrying out work
• Example: high-voltage electrical energy
Many of our most common energy sources are lowquality and must be concentrated or transformed into
high-quality sources before they are useful to us.
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Conservation of Matter
Under ordinary circumstances, matter is
neither created nor destroyed. It is recycled
endlessly.
• Matter is transformed and combined in different
ways, but it doesn't disappear. Everything goes
somewhere.
• The atoms and molecules in your body have passed
through many other organisms, over millions of
years.
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Properties of Energy
Energy cannot be recycled. Energy is reused, but it
is constantly degraded or lost from the system.
Most energy used in ecosystems originates as
solar energy. Green plants convert some of this
energy to chemical energy, which is then converted
to heat or kinetic energy by the animal that eats the
plant.
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Laws of Thermodynamics
First Law of Thermodynamics
Energy cannot be created or destroyed, only changed
Second Law of Thermodynamics
With each successive energy transfer or
transformation in a system, less energy is available to
do work. Even though the the total amount of energy
remains the same, the energy's intensity and
usefulness deteriorate.
The second law recognizes the principle of entropy,
the tendency of all natural systems to move towards a
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state of increasing disorder.
Atoms, Molecules, and
Compounds
• Most material substances can exist in three
interchangeable states: solid, liquid, or gas.
• Element - substance that cannot be broken down
into simpler substances by ordinary chemical
reactions
• Atom - the smallest particle that exhibits the
characteristics of an element
• Molecule - a combination of two or more atoms
• Compound - a molecule made up of two or more
kinds of atoms held together by chemical bonds
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Fig. 2.3
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Periodic Table of the Elements
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Elements and Environmental
Science
Just four elements - carbon, hydrogen, oxygen, and
nitrogen - make up over 96% of the mass of most
organisms.
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Chemical Bonding
• Ionic Bond - Formed when one atom gives
up an electron to another atom.
• Covalent Bond - Formed when two or more
atoms share electrons.
– Energy is needed to break chemical bonds.
– Energy is released when bonds are formed.
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Fig. 2.4
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Water Molecule
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Water: A Unique Compound
•
•
•
•
•
•
•
•
Sixty to 70 percent of the weight of living organisms
Medium in which all of life's chemical reactions occur
Good electrical conductor
Highest surface tension of any common, natural liquid
Liquid over a wide temperature range
Expands when it crystallizes, unlike most substances
High heat of vaporization
High specific heat
24
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A Chemical Reaction
Chemical reactions, the breaking and forming of
molecular bonds, create all the simple and complex
compounds and substances on which life depends.
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Acids and Bases
• Acids are compounds that readily release
hydrogen ions (H+) in water.
• Bases are substances that readily take up
hydrogen ions (H+) and release hydroxide
ions (OH-) in solution.
• Strength measured by concentration of H+.
– pH scale
• 0-14
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Fig. 2.5
28
Cells: The Fundamental Units
of Life
• Microscopic organisms, such as bacteria and
protozoa, are composed of single cells.
• The human body contains several trillion cells of
about two hundred distinct types.
• Enzymes – catalysts that speed up the rate of
chemical reactions in living systems
• Metabolism - all the energy and matter exchanges
that occur within a living cell or organism
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The Electromagnetic
Spectrum
The wavelengths of visible
light drive photosynthesis.
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Photosynthesis
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Light and Dark
Reactions of
Photosynthesis
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Respiration
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Energy Exchange in
an Ecosystem
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Part 2:
Organizing
Living Things
•
•
•
•
•
•
Organism
Population
Biological
Community
Ecosystem
Biosphere
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Food Web: Cross-connected Food
Chains
36
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Energy Pyramid
Most energy in most ecosystems is stored in the bodies of
primary producers. Only about 10 percent of the energy
at one energy level passes to the next highest trophic level.
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Bioaccumulation
Lake Laberge, a remote lake in northwestern Canada, has been
affected by organic chemicals that have been transported
thousands of kilometers by wind and weather. The biggest fish in
the lake are extremely contaminated due to bioaccumulation, a
steady accumulation of toxins through food webs.
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The Carbon Cycle
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The Nitrogen Cycle
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Nitrogen
Fixation
The nodules on the roots
of this plant contain
bacteria that help convert
nitrogen in the soil to a
form the plant can utilize.
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The Phosphorous Cycle
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The Sulfur Cycle
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