LIVING IN THE ENVIRONMENT 17 TH MILLER/SPOOLMAN CHAPTER 2 Science, Matter, Energy, and Systems

Core Case Study: A Story About a Forest Hubbard Brook Experimental Forest in New Hampshire Compared the loss of water and nutrients from an uncut forest (control site) with one that had been stripped (experimental site) Stripped site: 30-40% more runoff More dissolved nutrients More soil erosion

The Effects of Deforestation on the Loss of Water and Soil Nutrients Fig. 2-1, p. 31

2-1 What Do Scientists Do? Concept 2-1 Scientists collect data and develop theories, models, and laws about how nature works.

Science Is a Search for Order in Nature (1) Identify a problem Find out what is known about the problem Ask a question to be investigated Gather data through experiments Propose a scientific hypothesis

Science Is a Search for Order in Nature (2) Make testable predictions Keep testing and making observations Accept or reject the hypothesis Scientific theory: well-tested and widely accepted hypothesis

The Scientific Process Fig. 2-2, p. 33

Identify a problem Find out what is known about the problem (literature search) Ask a question to be investigated Perform an experiment to answer the question and collect data Analyze data (check for patterns) Scientific law Well-accepted pattern in data Propose a hypothesis to explain data Use hypothesis to make testable projections Perform an experiment to test projections Accept hypothesis Revise hypothesis Make testable projections Test projections Scientific theory Well-tested and widely accepted hypothesis

Testing a Hypothesis Fig. 2-3, p. 33

Nothing happens when I try to turn on my flashlight. Question: Why didn’t the light come on? Hypothesis: Maybe the batteries are dead. Test hypothesis with an experiment: Put in new batteries and try to turn on the flashlight. Result: Flashlight still does not work. New hypothesis: Maybe the bulb is burned out. Experiment: Put in a new bulb. Result: Flashlight works. Conclusion: New hypothesis is verified. Observation:

Characteristics of Science…and Scientists Curiosity Skepticism Reproducibility Peer review Openness to new ideas Critical thinking Creativity

Science Focus: Easter Island: Revisions to a Popular Environmental Story Some revisions to a popular environmental story Polynesians arrived about 800 years ago Population may have reached 3000 Used trees in an unsustainable manner, but rats may have multiplied and eaten the seeds of the trees

Stone Statues on Easter Island Fig. 2-A, p. 35

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

The Results of Science Can Be Tentative, Reliable, or Unreliable Tentative science, frontier science Reliable science Unreliable science

Science Has Some Limitations 1.Particular hypotheses, theories, or laws have a high probability of being true while not being absolute 2.Bias can be minimized by scientists 3.Environmental phenomena involve interacting variables and complex interactions 4.Statistical methods may be used to estimate very large or very small numbers 5.Scientific process is limited to the natural world

Science Focus: Statistics and Probability Statistics Collect, organize, and interpret numerical data Probability The chance that something will happen or be valid Need large enough sample size

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 Elements Unique properties Cannot be broken down chemically into other substances Compounds Two or more different elements bonded together in fixed proportions

Gold and Mercury Are Chemical Elements Fig. 2-4a, p. 38

Chemical Elements Used in The Book Table 2-1, p. 38

Atoms, Ions, and Molecules Are the Building Blocks of Matter (1) Atomic theory All elements are made of atoms Subatomic particles Protons with positive charge and neutrons with no charge in nucleus Negatively charged electrons orbit the nucleus Atomic number Number of protons in nucleus Mass number Number of protons plus neutrons in nucleus

Model of a Carbon-12 Atom Fig. 2-5, p. 39

6 protons 6 neutrons 6 electrons

Atoms, Ions, and Molecules Are the Building Blocks of Matter (2) Isotopes Same element, different number of protons Ions Gain or lose electrons Form ionic compounds pH Measure of acidity H + and OH -

Chemical Ions Used in This Book Table 2-2, p. 40

pH Scale Supplement 5, Figure 4

Loss of NO 3 − from a Deforested Watershed Fig. 2-6, p. 40

Undisturbed (control) watershed Disturbed (experimental) watershed Nitrate (NO 3 – ) concentration (milligrams per liter) Year

Atoms, Ions, and Molecules Are the Building Blocks of Matter (3) Molecule Two or more atoms of the same or different elements held together by chemical bonds Compounds Chemical formula

Compounds Used in This Book Table 2-3, p. 40

Organic Compounds Are the Chemicals of Life Organic compounds Hydrocarbons and chlorinated hydrocarbons Simple carbohydrates Macromolecules: complex organic molecules Complex carbohydrates Proteins Nucleic acids Lipids Inorganic compounds

Glucose Structure Supplement 4, Fig. 4

Amino Acids and Proteins Supplement 4, Fig. 8

Nucleotide Structure in DNA and RNA Supplement 4, Fig. 9

DNA Double Helix Structure and Bonding Supplement 4, Fig. 10

Fatty Acid Structure and Trigyceride Supplement 4, Fig. 11

Matter Comes to Life through Genes, Chromosomes, and Cells Cells: fundamental units of life; all organisms are composed of one or more cells Genes Sequences of nucleotides within DNA Instructions for proteins Create inheritable traits Chromosomes: composed of many genes

Cells, Nuclei, Chromosomes, DNA, and Genes Fig. 2-7, p. 42

A human body contains trillions of cells, each with an identical set of genes. Each human cell (except for red blood cells) contains a nucleus. 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 proteins—the building blocks of life.

Some Forms of Matter Are More Useful than Others High-quality matter Highly concentrated Near earth’s surface High potential as a resource Low-quality matter Not highly concentrated Deep underground or widely dispersed Low potential as a resource

Examples of Differences in Matter Quality Fig. 2-8, p. 42

High QualityLow Quality SolidGas Salt Solution of salt in water Coal Coal-fired power plant emissions Gasoline Automobile emissions Aluminum canAluminum ore

2-3 What Happens When Matter Undergoes Change? Concept 2-3 Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter).

Matter Undergoes Physical, Chemical, and Nuclear Changes Physical change No change in chemical composition Chemical change, chemical reaction Change in chemical composition Reactants and products Nuclear change Natural radioactive decay Radioisotopes: unstable Nuclear fission Nuclear fusion

Types of Nuclear Changes Fig. 2-9, p. 43

Fig. 2-9a, p. 43 Radioactive decay occurs when nuclei of unstable isotopes spontaneously emit fast-moving chunks of matter (alpha particles or beta particles), high- energy radiation (gamma rays), or both at a fixed rate. A particular radioactive isotope may emit any one or a combination of the three items shown in the diagram. Radioactive isotope Radioactive decay Gamma rays Alpha particle (helium-4 nucleus) Beta particle (electron)

Fig. 2-9b, p. 43 Nuclear fission Uranium-235 Neutron Energy Fission fragment n n n n n n Energy Fission fragment Radioactive isotope Radioactive decay occurs when nuclei of unstable isotopes spontaneously emit fast-moving chunks of matter (alpha particles or beta particles), high- energy radiation (gamma rays), or both at a fixed rate. A particular radioactive isotope may emit any one or a combination of the three items shown in the diagram.

Fig. 2-9c, p. 43 Nuclear fusion occurs when two isotopes of light elements, such as hydrogen, are forced together at extremely high temperatures until they fuse to form a heavier nucleus and release a tremendous amount of energy. Hydrogen-3 (tritium nucleus) 100 million °C Reaction conditions Neutron Energy Products Neutron Nuclear fusion Fuel Hydrogen-2 (deuterium nucleus) Helium-4 nucleus Proton

We Cannot Create or Destroy Matter Law of conservation of matter Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed

2-4 What is Energy and What Happens When It Undergoes Change? 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 in a physical or chemical change, we end up with lower-quality or less usable energy than we started with (second law of thermodynamics).

Energy Comes in Many Forms (1) Kinetic energy Flowing water Wind Heat Transferred by radiation, conduction, or convection Electromagnetic radiation Potential energy Stored energy Can be changed into kinetic energy

Wind’s Kinetic Energy Moves This Turbine Fig. 2-10, p. 44

The Electromagnetic Spectrum Fig. 2-11, p. 45

Visible light Gamma rays X rays Shorter wavelengths and higher energy Longer wavelengths and lower energy UV radiation Infrared radiation MicrowavesTV, Radio waves Wavelengths (not to scale) NanometersMicrometersCentimetersMeters

Potential Energy Fig. 2-12, p. 45

Energy Comes in Many Forms (2) Sun provides 99% of earth’s energy Warms earth to comfortable temperature Plant photosynthesis Winds Hydropower Biomass Fossil fuels: oil, coal, natural gas

Nuclear Energy to Electromagnetic Radiation Fig. 2-13, p. 46

Fossil fuels Fig. 2-14a, p. 46

Some Types of Energy Are More Useful Than Others High-quality energy High capacity to do work Concentrated High-temperature heat Strong winds Fossil fuels Low-quality energy Low capacity to do work Dispersed

Ocean Heat Is Low-Quality Energy Fig. 2-15, p. 47

Energy Changes Are Governed by Two Scientific Laws First Law of Thermodynamics Law of conservation of energy Energy is neither created nor destroyed in physical and chemical changes Second Law of Thermodynamics Energy always goes from a more useful to a less useful form when it changes from one form to another Light bulbs and combustion engines are very inefficient: produce wasted heat

Energy-Wasting Technologies Fig. 2-16a, p. 48

2-5 What Are Systems and How Do They Respond to Change? Concept 2-5 Systems have inputs, flows, and outputs of matter and energy, and feedback can affect their behavior.

Systems Have Inputs, Flows, and Outputs System Set of components that interact in a regular way Human body, earth, the economy Inputs from the environment Flows, throughputs of matter and energy Outputs to the environment

Inputs, Throughput, and Outputs of an Economic System Fig. 2-17, p. 48

Inputs (from environment) Throughputs Outputs (to environment) Energy resources Work or products Matter resources System processes Waste and pollution Information Heat

Systems Respond to Change through Feedback Loops Positive feedback loop Causes system to change further in the same direction Can cause major environmental problems Negative, or corrective, feedback loop Causes system to change in opposite direction

Positive Feedback Loop Fig. 2-18, p. 49

Decreasing vegetation which causes more vegetation to die.... leads to erosion and nutrient loss...

Negative Feedback Loop Fig. 2-19, p. 50

House warms Temperature reaches desired setting and furnace goes off Furnace on Furnace off House cools Temperature drops below desired setting and furnace goes on

Time Delays Can Allow a System to Reach a Tipping Point Time delays vary Between the input of a feedback stimulus and the response to it Tipping point, threshold level Causes a shift in the behavior of a system Melting of polar ice Population growth

System Effects Can Be Amplified through Synergy Synergistic interaction, synergy Two or more processes combine in such a way that combined effect is greater than the two separate effects Helpful Studying with a partner Harmful E.g., Smoking and inhaling asbestos particles

The Usefulness of Models for Studying Systems 1.Identify major components of systems and interactions within system, and then write equations 2.Use computer to describe behavior, based on the equations 3.Compare projected behavior with known behavior Can use a good model to answer “if-then“ questions

Three Big Ideas 1.There is no away. 2.You cannot get something for nothing. 3.You cannot break even.