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SUSTAINING THE MILLER/SPOOLMAN EARTH | G. TYLER MILLER | SCOTT E. SPOOLMAN 11e 2 Science, Matter, Energy, and Systems © Cengage Learning 2015 2-1 What Do Scientists Do? • Science is a search for order in nature – The scientific method • Identify a problem • Find out what is known about the problem • Ask a question to investigate • Collect data to answer the question • Propose a scientific hypothesis © Cengage Learning 2015 Science Is a Search for Order in Nature (cont’d.) • The scientific method (cont’d.) – Make testable projections – Test the projections with further experiments, models, or observations – Accept or reject the hypothesis • Scientific theory: well-tested and widely accepted hypothesis • Scientific law (law of nature) © Cengage Learning 2015 The Results of Science Can Be Tentative, Reliable, or Unreliable • Tentative science (frontier science) • Reliable science – Scientific consensus • Unreliable science © Cengage Learning 2015 Science Has Some Limitations • Scientists cannot prove or disprove anything absolutely • Scientists are not totally bias free • Many natural world systems involve a huge number of variables with complex interactions • Statistical methods are necessary when direct measures are not possible © Cengage Learning 2015 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 © Cengage Learning 2015 2-2 What Is Matter and What Happens When It Undergoes Change? • Matter consists of elements and compounds – Matter: has mass and takes up space – Elements: fundamental type of matter • Cannot be broken down chemically into other substances – Compounds: two or more different elements bonded together in fixed proportions © Cengage Learning 2015 Matter Consists of Elements and Compounds (cont’d.) – 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 © Cengage Learning 2015 Atoms, Molecules, and Ions Are the Building Blocks of Matter • Atomic theory: all elements are made of atoms • Subatomic particles – Neutrons: no electrical charge – Protons: positive electrical charge – Electrons: negative electrical charge • Atom – Nucleus and an electron probability cloud © Cengage Learning 2015 Atoms, Molecules, and Ions Are the Building Blocks of Matter (cont’d.) • Atomic number – Number of protons in the atom’s nucleus • Mass number – Total number of neutrons and protons in the atom’s nucleus • Isotopes – Forms of an element having the same atomic number but different mass numbers © Cengage Learning 2015 Atoms, Molecules, and Ions Are the Building Blocks of Matter (cont’d.) • Molecule – Two or more atoms of the same or different elements held together by chemical bonds • Ions – An atom or a group of atoms with one or more net positive or negative electrical charges • pH – Measure of acidity based on comparative amounts of H+ and OH© Cengage Learning 2015 Organic Compounds Are the Chemicals of Life • Organic compounds – Hydrocarbons – Chlorinated hydrocarbons – Simple carbohydrates (simple sugars) – Macromolecules: complex organic molecules • Major types of organic polymers: complex carbohydrates, proteins, and nucleic acids • Lipids • Inorganic compounds © Cengage Learning 2015 Matter Comes to Life through Genes, Chromosomes, and Cells • Genes: certain sequences of nucleotides – Traits • Chromosome: consists of thousands of genes • Cells: fundamental units of life © Cengage Learning 2015 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. Stepped Art Fig. 2-4 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 • Matter quality – 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 © Cengage Learning 2015 Matter Can Undergo Change but Cannot Be Created or Destroyed • Physical change – No change in chemical composition • Chemical change (chemical reaction) – Change in chemical composition – Reactants and products • Law of conservation of matter © Cengage Learning 2015 2-3 What is Energy and What Happens When It Undergoes Change? • Energy comes in many forms and some are more useful than others – Kinetic energy • Energy associated with motion • Heat • Electromagnetic radiation – Potential energy: stored energy • Can be changed into kinetic energy © Cengage Learning 2015 Visible light Shorter wavelengths Gamma rays and higher energy Wavelengths (not to scale) Fig. 2-6 X rays Nanometers UV radiation Infrared TV, Radio radiation Microwaves waves Micrometers Centimeters Meters Longer wavelengths and lower energy Energy Comes in Many Forms (cont’d.) • Solar energy principle of sustainability • Energy quality – High-quality energy • Concentrated • Great capacity to do useful work – Low-quality energy • Dispersed • Little capacity to do useful work © Cengage Learning 2015 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 – When energy is changed from one form to another, it always goes from a more useful to a less useful form © Cengage Learning 2015 2-4 What Keeps Us and Other Organisms Alive? • Ecology is the study of connections in nature – Organism: any form of life – Species: set organisms • Resemble one another in appearance, behavior, chemistry, and genetic makeup © Cengage Learning 2015 Science Focus: Have You Thanked the Insects Today? • Insects’ vital roles in helping to sustain life on earth – Pollinating – Eating other insects • Helping control pests – Loosening and renewing the soil © Cengage Learning 2015 Life Is Organized Within Populations, Communities, and Ecosystems – Population • Genetic diversity • Habitat – Biological community (community) – Ecosystem – Biosphere © Cengage Learning 2015 Biosphere Parts of the earth's air, water, and soil where life is found Ecosystem A community of different species interacting with one another and with their nonliving environment of matter and energy Community Populations of different species living in a particular place, and potentially interacting with each other Population A group of individuals of the same species living in a particular place Organism An individual living being Cell The fundamental structural and functional unit of life Molecule Chemical combination of two or more atoms of the same or different elements Atom Smallest unit of a chemical element that exhibits its chemical properties Water Stepped Art Fig. 2-8 Hydrogen Oxygen Earth’s Life-Support System Has Four Major Components • Atmosphere – Troposphere: inner layer – Stratosphere: contains ozone layer • Hydrosphere • Geosphere • Biosphere – Biomes – Aquatic life zones © Cengage Learning 2015 Atmosphere Biosphere (living organisms) Soil Rock Crust Mantle Geosphere (crust, mantle, core) Mantle Core Atmosphere (air) Hydrosphere (water) Fig. 2-9 Three Factors Sustain the Earth’s Life • One-way flow of high-quality energy – Two laws of thermodynamics • Cycling of nutrients through parts of the biosphere – Fixed supply • Gravity holds earths atmosphere © Cengage Learning 2015 Sun, Earth, Life, and Climate • Sun’s energy – Reaches the earth as electromagnetic waves • UV radiation, visible light, and heat – Absorbed or reflected back into space by the earth’s atmosphere and surface • Natural greenhouse effect © Cengage Learning 2015 2-5 What Are the Major Components of an Ecosystem? • Ecosystems have living and nonliving components – Biotic: living components – Abiotic: nonliving components • Range of tolerance – Optimum level or range • Limiting factor principle – Impact of too much/little of any abiotic factor © Cengage Learning 2015 Oxygen (O2) Precipitation Carbon dioxide (CO2) Producer Secondary consumer (fox) Primary consumer (rabbit) Producers Water Fig. 2-11 Decomposers Soluble mineral nutrients Producers and Consumers Are the Living Components of Ecosystems • Producers (autotrophs) – Photosynthesis: • CO2 + H2O + solar energy → glucose + oxygen • Consumers (heterotrophs) – Primary consumers (herbivores) – Secondary consumers – Tertiary (higher) consumers – Omnivores © Cengage Learning 2015 Producers and Consumers Are the Living Components of Ecosystems (cont’d.) • Decomposers – Consumers that release nutrients – Bacteria and fungi • Detritus feeders (detritivores) – Feed on dead bodies of other organisms – Earthworms, some insects, and vultures • Aerobic respiration – glucose + oxygen → CO2 + H2O + energy © Cengage Learning 2015 Decomposers Detritus feeders Bark beetle engraving Long-horned beetle holes Carpenter ant galleries Termite and carpenter ant work Dry rot fungus Wood reduced Mushroom to powder Time progression Fig. 2-13 Powder broken down by decomposers into plant nutrients in soil Heat Chemical nutrients (carbon dioxide, oxygen, nitrogen, minerals) Heat Heat Producers (plants) Decomposers (bacteria, fungi) Heat Fig. 2-14 Solar energy Consumers (plant eaters, meat eaters) Heat Science Focus: Many of the World’s Most Important Species Are Invisible to Us • Microbes (microorganisms) – Bacteria – Protozoa – Fungi – Floating phytoplankton © Cengage Learning 2015 Natural Systems Have Tipping Points • Threshold level (ecological tipping point) • Tipping points currently being faced – Collapse of certain populations of fish • Overfishing – Premature extinction of thousands of species • Overhunting and habitat destruction – Long-term climate disruption • Gas emissions © Cengage Learning 2015 2-6 What Happens to Energy in an Ecosystem? • Energy flows through ecosystems in food chains and food webs – Food chain • Movement of energy and nutrients from one trophic level to the next • Photosynthesis → feeding → decomposition – Food web • Network of interconnected food chains © Cengage Learning 2015 First Trophic Level Second Trophic Level Third Trophic Level Fourth Trophic Level Producers (plants) Primary consumers (herbivores) Secondary consumers (carnivores) Tertiary consumers (top carnivores) Heat Heat Heat Heat Solar energy Heat Heat Heat Decomposers and detritus feeders Fig. 2-16 Humans Sperm whale Blue whale Elephant seal Crabeater seal Adelie penguin Killer whale Leopard seal Emperor penguin Petrel Squid Fish Carnivorous zooplankton Krill Fig. 2-17 Herbivorous zooplankton Phytoplankton Usable Energy Decreases with Each Link in a Food Chain or Web • Biomass – Dry weight of all organic matter of a given trophic level in a food chain or food web – Decreases at each higher trophic level due to heat loss • Ecological efficiency – Pyramid of energy flow • Ninety percent energy loss with each transfer • Less chemical energy at higher trophic levels © Cengage Learning 2015 Usable energy available at each trophic level (in kilocalories) Tertiary consumers (human) 10 Secondary consumers (perch) 100 Primary consumers (zooplankton) Heat Heat 1,000 Heat 10,000 Producers (phytoplankton) Stepped Art Fig. 2-18 Heat Decomposers Heat Some Ecosystems Produce Plant Matter Faster Than Others Do • Gross primary productivity (GPP) – Conversion rate of solar energy to chemical energy • Net primary productivity (NPP) – Measure of how fast producers can make the chemical energy that is stored in their tissues • Ecosystems and life zones differ in their NPP © Cengage Learning 2015 Fig. 2-19 2-7 What Happens to Matter in an Ecosystem? • Nutrients cycle in the biosphere – Biogeochemical cycles (nutrient cycles) – Cycles • Driven directly or indirectly by incoming solar energy and the earth’s gravity • Include hydrologic (water), carbon, nitrogen, phosphorus, and sulfur cycles © Cengage Learning 2015 The Water Cycle • Major processes – Evaporation – Precipitation – Transpiration • Natural renewal of water quality © Cengage Learning 2015 Human Activities Have Major Effects on the Water Cycle • Withdrawing large amounts of freshwater at rates faster than nature can replace it • Clearing vegetation – Increases runoff and reduces amount of water seeping into the ground • Draining wetlands – Increases flooding © Cengage Learning 2015 Condensation Ice and snow Condensation Transpiration from plants Precipitation to land Evaporation of surface water Runof f Lakes and reservoirs Infiltration and percolation into aquifer Groundwater in aquifers Evaporation from ocean Runoff Increased runoff on land covered with crops, buildings and pavement Runoff Overpumping of aquifers Runoff Increased runoff from cutting forests and filling wetlands Water pollution Ocean Natural process Natural reservoir Human impacts Natural pathway Fig. 2-20 Pathway affected by human activities Precipitation to ocean The Carbon Cycle • Link between photosynthesis in producers and aerobic respiration in producers, consumers, and decomposers – Circulates carbon in the biosphere © Cengage Learning 2015 Carbon dioxide in atmosphere Respiration Photosynthesis Animals (consumers) Diffusion Burning fossil fuels Forest fires Plants (producers) Deforestation Transportation Carbon dioxide dissolved in ocean Marine food webs Producers, consumers, decomposers Carbon in limestone or dolomite sediments Fig. 2-21 Process Reservoir Pathway affected by humans Natural pathway Respiration Carbon in animals (consumers) Carbon in plants (producers) Decomposition Compaction Carbon in fossil fuels Human Activities Affect the Carbon Cycle • Additional CO2 added to the atmosphere – Tree clearing – Burning of fossil fuels • Increased atmospheric CO2 and other greenhouse gases – Could lead to climate disruption © Cengage Learning 2015 The Nitrogen Cycle: Bacteria in Action • Nitrogen-fixing – Lightning – Nitrogen-fixing bacteria • Major parts of the cycle – Nitrogen fixation – Nitrification – Ammonification – Denitrification © Cengage Learning 2015 Human Activities Affect the Nitrogen Cycle • Burning fossil fuels – Acid rain • Adding N2O to the atmosphere through – Bacteria acting on fertilizers and manure • Destroying forests, grasslands, and wetlands – Releases stored nitrogen © Cengage Learning 2015 Human Activities Affect the Nitrogen Cycle (cont’d.) • Increasing nitrates in bodies of water – Agricultural runoff and sewage discharges • Removing nitrogen from topsoil – Harvesting crops and clearing grasslands and forests © Cengage Learning 2015 The Phosphorus Cycle and Human Interference with It • Cycles through water, the earth’s crust, and living organisms • Limiting factor for plant growth • Impact of human activities – Removing large amounts of phosphate from the earth to make fertilizers and detergents – Clearing tropical forests – Erosion leaches phosphates into streams © Cengage Learning 2015 Process Reservoir Pathway affected by humans Natural pathway Phosphates in sewage Phosphates in mining waste Phosphates in fertilizer Runoff Runoff Sea birds Runoff Erosion Animals (consumers) Phosphate dissolved in water Plants (producers) Bacteria Fig. 2-23 Plate tectonics Phosphate in rock (fossil bones, guano) Phosphate in shallow ocean sediments Ocean food webs Phosphate in deep ocean sediments Earth’s Rocks Are Recycled Very Slowly • Igneous rock – Form below or at earth’s surface from molten material • Sedimentary rock – Created from sediments under pressure • Metamorphic rock – Existing rocks subjected to high temperatures, high pressures, and/or chemically active fluids © Cengage Learning 2015 Three Big Ideas • According to the law of conservation of matter, no atoms are created or destroyed whenever matter undergoes a physical or chemical change. © Cengage Learning 2015 Three Big Ideas (cont’d.) • According to the laws of thermodynamics, whenever energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed, and we always end up with lower-quality or less usable energy than we started with. © Cengage Learning 2015 Three Big Ideas (cont’d.) • Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity. © Cengage Learning 2015 The second law of thermodynamics holds, I think, the supreme position among laws of nature. . . . If your theory is found to be against the second law of thermodynamics, I can give you no hope. Henry David Thoreau © Cengage Learning 2015