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from your text, Principles of EnvironmentalScience: Inquiry and Applications, 2nd ed.

William and Mary Ann Cunningham. (New York: McGraw-Hill, 2003)

Chapter Two: Principles of Ecology: Matter, Energy and Life

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Required ReadingChapter 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 ObjectivesObjectives

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

Atom

Bases

Biological community

Biomass

Carbon cycle

Carnivores

Cellular respiration

Compound

Conservation of matter

Consumers

Decomposer

Ecology

Ecosystem

Energy

First law of thermodynamics

Food web

Herbivores

Ions

Kinetic energy

Matter

Metabolism

Molecules

Nitrogen cycle

Omnivores

Organic compounds

pH

Photosynthesis

Potential energy

Primary producers

Productivity

Second law of thermodynamics

Species

Tropic level

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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 - 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.

Heat and Temperature

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Energy QualityLow 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 low-quality 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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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 state of increasing disorder.

Laws of Thermodynamics

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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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Just four elements - carbon, hydrogen, oxygen, and nitrogen - make up over 96% of the mass of most

organisms.

Elements and Environmental Science

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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

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Chemical reactions, the breaking and forming of molecular bonds, create all the simple and complexcompounds and substances on which life depends.

A Chemical Reaction

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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

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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 wavelengths of visiblelight drive photosynthesis.

The Electromagnetic Spectrum

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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

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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.

Energy Pyramid

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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.

Bioaccumulation

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The Carbon Cycle

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The Nitrogen Cycle

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The nodules on the rootsof this plant contain bacteria that help convertnitrogen in the soil to a form the plant can utilize.

Nitrogen Fixation

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The Phosphorous Cycle

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The Sulfur Cycle