Science, Systems, Matter, and Energy

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Chapter 2

• Science, Systems, Matter, and Energy

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Core Case Study Environmental Lesson from
Easter Island

• Thriving society
• 15,000 people by 1400.
• Used resources faster than could be renewed
• By 1600 only a few trees remained.
• Civilization collapsed
• By 1722 only several hundred people left.

Figure 2-1
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Video Easter Island
PLAY VIDEO

• From ABC News, Environmental Science in the
  Headlines, 2005 DVD.

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THE NATURE OF SCIENCE

• What do scientists do?
• Collect data.
• Form hypotheses.
• Develop theories, models and laws about how
  nature works.

Figure 2-2
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Ask a question
Do experiments and collect data
Interpret data
Well-tested and accepted patterns in data
become scientific laws
Formulate hypothesis to explain data
Do more experiments to test hypothesis
Revise hypothesis if necessary
Well-tested and accepted hypotheses become scienti
fic theories
Fig. 2-2, p. 29
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Stepped Art
Fig. 2-3, p. 30
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Scientific Theories and Laws The Most Important
Results of Science

• Scientific Theory
• Widely tested and accepted hypothesis.
• Scientific Law
• What we find happening over and over again in
  nature.

Figure 2-3
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Research results
Scientific paper
Peer review by experts in field
Paper rejected
Paper accepted
Paper published in scientific journal
Research evaluated by scientific community
Fig. 2-3, p. 30
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Testing Hypotheses

• Scientists test hypotheses using controlled
  experiments and constructing mathematical models.
• Variables or factors influence natural processes
• Single-variable experiments involve a control and
  an experimental group.
• Most environmental phenomena are multivariable
  and are hard to control in an experiment.
• Models are used to analyze interactions of
  variables.

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Scientific Reasoning and Creativity

• Inductive reasoning
• Involves using specific observations and
  measurements to arrive at a general conclusion or
  hypothesis.
• Bottom-up reasoning going from specific to
  general.
• Deductive reasoning
• Uses logic to arrive at a specific conclusion.
• Top-down approach that goes from general to
  specific.

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Frontier Science, Sound Science, and Junk Science

• Frontier science has not been widely tested
  (starting point of peer-review).
• Sound science consists of data, theories and laws
  that are widely accepted by experts.
• Junk science is presented as sound science
  without going through the rigors of peer-review.

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Limitations of Environmental Science

• Inadequate data and scientific understanding can
  limit and make some results controversial.
• Scientific testing is based on disproving rather
  than proving a hypothesis.
• Based on statistical probabilities.

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MODELS AND BEHAVIOR OF SYSTEMS

• Usefulness of models
• Complex systems are predicted by developing a
  model of its inputs, throughputs (flows), and
  outputs of matter, energy and information.
• Models are simplifications of real-life.
• Models can be used to predict if-then scenarios.

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TYPES AND STRUCTURE OF MATTER

• Elements and Compounds
• Matter exists in chemical forms as elements and
  compounds.
• Elements (represented on the periodic table) are
  the distinctive building blocks of matter.
• Compounds two or more different elements held
  together in fixed proportions by chemical bonds.

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Atoms
Figure 2-4
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Ions

• An ion is an atom or group of atoms with one or
  more net positive or negative electrical charges.
• The number of positive or negative charges on an
  ion is shown as a superscript after the symbol
  for an atom or group of atoms
• Hydrogen ions (H), Hydroxide ions (OH-)
• Sodium ions (Na), Chloride ions (Cl-)

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• The pH (potential of Hydrogen) is the
  concentration of hydrogen ions in one liter of
  solution.

Figure 2-5
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Animation pH Scale
PLAY ANIMATION
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Compounds and Chemical Formulas

• Chemical formulas are shorthand ways to show the
  atoms and ions in a chemical compound.
• Combining Hydrogen ions (H) and Hydroxide ions
  (OH-) makes the compound H2O (dihydrogen oxide,
  a.k.a. water).
• Combining Sodium ions (Na) and Chloride ions
  (Cl-) makes the compound NaCl (sodium chloride
  a.k.a. salt).

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Organic Compounds Carbon Rules

• Organic compounds contain carbon atoms combined
  with one another and with various other atoms
  such as H, N, or Cl-.
• Contain at least two carbon atoms combined with
  each other and with atoms.
• Methane (CH4) is the only exception.
• All other compounds are inorganic.

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Cells The Fundamental Units of Life

• Cells are the basic structural and functional
  units of all forms of life.
• Prokaryotic cells (bacteria) lack a distinct
  nucleus.
• Eukaryotic cells (plants and animals) have a
  distinct nucleus.

Figure 2-6
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(a) Prokaryotic Cell
DNA(information storage, no nucleus)
Cell membrane (transport of raw materials and
finished products)
Protein construction and energy conversion occur
without specialized internal structures
Fig. 2-6a, p. 37
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(b) Eukaryotic Cell
Energy conversion
Nucleus (information storage)
Protein construction
Cell membrane (transport of raw materials
and finished products)
Packaging
Fig. 2-6b, p. 37
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Animation Prokaryotic and Eukaryotic Cells
PLAY ANIMATION
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Macromolecules, DNA, Genes and Chromosomes

• Large, complex organic molecules (macromolecules)
  make up the basic molecular units found in living
  organisms.
• Complex carbohydrates
• Proteins
• Nucleic acids
• Lipids

Figure 2-7
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A human body contains trillions of cells, each
with an identical set of genes.
There is a nucleus inside each human cell (except
red blood cells).
Each cell nucleus has an identical set of
chromosomes, which are found in pairs.
A specific pair of chromosomes contains one
chromosome from each parent.
Each chromosome contains a long DNA molecule in
the form of a coiled double helix.
Genes are segments of DNA on chromosomes that
contain instructions to make proteinsthe
building blocks of life.
The genes in each cell are coded by sequences of
nucleotides in their DNA molecules.
Stepped Art
Fig. 2-7, p. 38
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States of Matter

• The atoms, ions, and molecules that make up
  matter are found in three physical states
• solid, liquid, gaseous.
• A fourth state, plasma, is a high energy mixture
  of positively charged ions and negatively charged
  electrons.
• The sun and stars consist mostly of plasma.
• Scientists have made artificial plasma (used in
  TV screens, gas discharge lasers, florescent
  light).

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ENERGY

• Energy is the ability to do work and transfer
  heat.
• Kinetic energy energy in motion
• heat, electromagnetic radiation
• Potential energy stored for possible use
• batteries, glucose molecules

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Electromagnetic Spectrum

• Many different forms of electromagnetic radiation
  exist, each having a different wavelength and
  energy content.

Figure 2-11
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Electromagnetic Spectrum

• Organisms vary in their ability to sense
  different parts of the spectrum.

Figure 2-12
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Animation Visible Light
PLAY ANIMATION
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Relative Energy Quality (usefulness)
Source of Energy
Energy Tasks
Electricity Very high temperature heat (greater
than 2,500C) Nuclear fission (uranium) Nuclear
fusion (deuterium) Concentrated
sunlight High-velocity wind
Very high-temperature heat (greater than 2,500C)
for industrial processes and producing
electricity to run electrical devices (lights,
motors)
High-temperature heat (1,0002,500C) Hydroge
n gas Natural gas Gasoline Coal Food
Mechanical motion to move vehicles and other
things) High-temperature heat (1,0002,500C)
for industrial processes and producing
electricity
Normal sunlight Moderate-velocity
wind High-velocity water flow Concentrated
geothermal energy Moderate-temperature
heat (1001,000C) Wood and crop wastes
Moderate-temperature heat (1001,000C) for
industrial processes, cooking, producing steam,
electricity, and hot water
Dispersed geothermal energy Low-temperature heat
(100C or lower)
Low-temperature heat (100C or less) for
space heating
Fig. 2-13, p. 44
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ENERGY LAWS TWO RULES WE CANNOT BREAK

• The first law of thermodynamics we cannot create
  or destroy energy.
• We can change energy from one form to another.
• The second law of thermodynamics energy quality
  always decreases.
• When energy changes from one form to another, it
  is always degraded to a more dispersed form.
• Energy efficiency is a measure of how much useful
  work is accomplished before it changes to its
  next form.

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Animation Total Energy Remains Constant
PLAY ANIMATION
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Mechanicalenergy(moving,thinking,living)
Chemical energy (photosynthesis)
Chemical energy (food)
Solar energy
Waste Heat
Waste Heat
Waste Heat
Waste Heat
Fig. 2-14, p. 45
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Animation Energy Flow
PLAY ANIMATION