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Science, Matter, Energy, and Ecosystems
Chapter 2
Objectives
SWBAT summarize and apply the scientific method.
SWBAT describe the components of matter and the phases of matter.
SWBAT differentiate between inorganic and organic compounds.
SWBAT summarize the four types of major macromolecules.
Objectives
SWBAT differentiate between physical and chemical changes.
SWBAT distinguish between various forms of energy and summarize the first and second laws of thermodynamics.
SWBAT describe the ways in which ecological systems depend on inputs and explain how scientists keep track of inputs, outputs and changes to complex systems.
2-1 What Is Science?
Concept 2-1 Scientists collect data and develop theories, models, and laws about how nature works.
Science Is a Search for Order in Nature
Identify a problem
Find out what is known about the problem
Ask a question to be investigated
Gather data
Hypothesize
Make testable predictions
Keep testing and making observations
Accept or reject the hypothesis
Science Is a Search for Order in Nature
Important features of the scientific process• Curiosity• Skepticism• Peer review• Reproducibility• Openness to new ideas
Scientific lawWell-acceptedpattern in data
Propose an hypothesisto explain data
Analyze data(check for patterns)
Ask a question to be investigated
Find out what is knownabout the problem(literature search)
Fig. 2-1, p. 22
Identify a problem
Perform an experimentto answer the question
and collect data
Use hypothesis to maketestable predictions
Perform an experimentto test predictions
Scientific theoryWell-tested andwidely accepted
hypothesis
Accepthypothesis
Revisehypothesis
Testpredictions
Make testablepredictions
Stepped Art
Scientific use reasoning to learn how nature works
Inductive Reasoning: using specific observations and measurements to arrive at a general conclusion or hypothesis.
Deductive Reasoning: use of logic to arrive at a specific conclusion based on a generalization of premise.
Scientific use reasoning to learn how nature works
Scientific Theories and Laws Are the Most Important Results of Science
Scientific theory• Widely tested• Supported by extensive evidence• Accepted by most scientists in a particular area
Scientific law, law of nature• well-tested, widely accepted description of what
we find happening consistently in nature• Example: law of gravity
The Results of Science Can Be Tentative, Reliable, or Unreliable
Tentative science, frontier science
Reliable science
Unreliable science
Science Focus: The Scientific Consensus over Global Warming
How much has the earth’s atmosphere warmed
during the last 50 years?
How much of this warming is due to human
activity?
How much is the atmosphere likely to warm in the
future?
Will this affect climate?
1988: Intergovernmental Panel on Climate
Change (IPCC)
Environmental Science Has Some Limitations
Particular hypotheses, theories, or laws have a
high probability of being true while not being
absolute
Bias can be minimized by scientists
Statistical methods may be used to estimate very
large or very small numbers
Environmental phenomena involve interacting
variables and complex interactions
Scientific process is limited to the natural world
2-2 What Is Matter?
Concept 2-2 Matter consists of elements and compounds, which are in turn made up of atoms, ions, or molecules.
Matter Consists of Elements and Compounds
Matter• Has mass and takes up space• Made of atoms
Elements• Basic building blocks of all matter• Made of only one type of atom
Molecule• Two or more atoms of the same or different elements held
together by chemical bonds
Compounds• Two or more different elements bonded together in fixed
proportions
Matter consists of elements and compounds
Atoms
Elements
ElementsUnique propertiesCannot be broken down chemically into other substances
Periodic Table of Elements
Atoms Are Building Blocks of Matter Atomic theory Subatomic particles• Protons (p+) with positive charge and neutrons (n0) with
no charge in nucleus• Negatively charged electrons (e-) orbit the nucleus
Atomic Number• Number of protons
Mass number • Protons plus neutrons
Isotopes• Atoms of the same element with different numbers of
neutrons
Atoms are the building blocks of matter
Ions: atoms with a charge• Gain or lose electrons• Form ionic compounds
pH• Measure of acidity• H+ and OH-
Gastric fluid (1.0–3.0)
Hydrochloric acid (HCl)
Lemon juice, some acid rain
BananasTomatoes
Typical rainwaterBread
Black coffee
Milk (6.6)Urine (5.0–7.0)
Blood (7.3–7.5)Pure water
Seawater (7.8–8.3)Egg white (8.0)
Phosphate detergentsBaking soda
Soapy solutions, Milk of magnesia
Bleach, Tums
Household ammonia (10.5–11.9)
Vinegar, wine, beer, oranges
Hair remover
Oven cleaner
Sodium hydroxide (NaOH)
Fig. 2-3, p. 27
Organic Compounds Are the Chemicals of Life
Inorganic compounds: any substance in which two or more chemical elements other than carbon are combined, nearly always in definite proportions.
Organic compounds• Hydrocarbons and chlorinated hydrocarbons• Simple carbohydrates• Macromolecules: complex organic molecules• Complex carbohydrates• Proteins• Nucleic acids• Lipids
Organization of Life
Organization of Life
Organization of Life
Matter Comes to Life through Genes, Chromosomes, and Cells
Cells: fundamental units of life
Genes: sequences of nucleotides within the DNA
Chromosomes: composed of many genes
A human body contains trillionsof cells, each with an identical setof genes.
Each human cell (except for redblood cells) contains a nucleus.
Each cell nucleus has an identical setof chromosomes, which are found inpairs.
A specific pair of chromosomescontains one chromosome from eachparent.
Each chromosome contains a longDNA molecule in the form of a coileddouble helix.
Genes are segments of DNA onchromosomes that contain instructionsto make proteins—the building blocksof life.
Fig. 2-4, p. 28
Some Forms of Matter Are More Useful than Others
High-quality matter
Low-quality matter
Aluminum can
High Quality
Solid
Salt
Coal
Gasoline
Aluminum ore
Low Quality
Solution of salt in water
Gas
Coal-fired powerplant emissions
Automobile emissions
Fig. 2-5, p. 28
2-3 How Can Matter Change?
Concept 2-3 When matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter).
2.3 We Cannot Create or Destroy Matter
Law of conservation of matter: when a physical or chemical change occurs, matter is neither created or destroyed, but merely changes form.
Matter consumption• Matter is converted from one form to another• Existing atoms are rearranged into different
spatial patterns (physical changes) or different combinations (chemical changes)
We Cannot Create or Destroy Matter
Physical change: arrangement of atoms does NOT change. NO new products formed.• Example: changing states, breaking glass
Chemical change, chemical reaction: bonds are broken and reformed and the arrangement of atoms changes. New products are formed.• Example: burning fuel, rusting metal, baking
Three Types of Nuclear Changes
Natural Radioactive Decay: isotopes spontaneously emit fast-moving subatomic particles.
Nuclear Fission: nuclei of certain isotopes with large mass numbers are split apart into lighter nuclei when struck by neutrons
Nuclear Fusion: two isotopes of lighter elements are forced together at extremely high temperatures until they fuse together to form a heavier nucleus.
2-4 What is Energy and How Can It Be Changed?
Concept 2-4A When energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed (first law of thermodynamics).
Concept 2-4B Whenever energy is changed from one form to another, we end up with lower- quality or less usable energy than we started with (second law of thermodynamics).
Energy Comes in Many Forms
Energy: capacity to do work or transfer heat. Kinetic energy • Heat• Transferred by radiation, conduction, or convection
• Electromagnetic radiation
Potential energy • Stored energy • Can be changed into kinetic energy
The Spectrum of Electromagnetic Radiation: Solar Capital
Some Types of Energy Are More Useful Than Others
Energy Quality: a measure of an energy source’s capacity to do work.
High-quality energy: nuclear fission, high-temperature heat, concentrated sunlight, high velocity wind, energy released from burning fossil fuels
Low-quality energy: dispersed. Heat in ocean
Energy Changes Are Governed by Two Scientific Laws
First Law of Thermodynamics• When energy is converted from one form to another,
no energy is created or destroyed• Energy input always equals energy output
Second Law of Thermodynamics• Energy always goes from a more useful to a less
useful form when it changes from one form to another Energy efficiency or productivity• A measure of how much useful work is accomplished
by a particular input of energy into a system
The Second Law of Thermodynamics in Living Systems
2-5 What are systems and How do they respond to change?
Concept 2-5A Systems have inputs, flows, and outputs of matter and energy, and their behavior can be affected by feedback.
Concept 2-5B Life, human systems, and the earth’s life-support systems must conform to the law of conservation of matter and the two laws of thermodynamics
What are systems and how do they respond to change?
System – a set of components that function and interact in some regular and theoretically predictable manner and can be isolated for the purposes of observation and study.
3 Key Components to Systems:o Inputs (matter, energy, information flowing into
system)o Flow or Throughputs (matter, energy, or information
flowing at a certain rate within a system)Stores or Storage Areas (area of accumulations for various lengths of time before being released)
o Outputs (matter, energy, or information that flow out of a system into sinks in the environment.
What are systems and how do they respond to change?
Feedback Loops – Occur when one change leads to some other change; can either reinforce or slow the original change.An output of matter, energy or information is fed back into the system as output.Positive Feedback Loop: a runaway cycle in which a change in a certain direction provides information that causes a system to change further in the same direction; can destabilize a system. Example: climate change, Hubbard brook experiment
Positive Feedback Loops
What are systems and how do they respond to change?
Negative Feedback Loop: one change leads to a lessening of that change; desirable, helps to stabilize a system. Example: homeostasis, thermostat, recycling
Feedback Loops
What are systems and how do they respond to change?
Homeostasis – (negative feedback loop) Defines as the maintenance of favorable internal conditions despite fluctuations in external conditions. (sweating to lower body temperature, shivering to raise body temperature)
What are systems and how do they respond to change?
Complex Systems – Involve multiple feedback loops; both negative and positive.
How is the tragedy of Easter Island an example of coupled negative and positive feedback loops?
Time Delay – involved in complex systems; the time between the input of a stimulus and the response to it. (allows a problem to build up slowly until it reaches a threshold level)
Synergistic Interaction – occurs when two or more processes interact so that the combined effects is greater than the sum of their separate parts.