Science, Matter, Energy, and Systems

1. 2 Science, Matter, Energy,and Systems

2. 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

3. 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)

4. The Results of Science Can Be Tentative, Reliable, or Unreliable • Tentative science (frontier science) • Reliable science • Scientific consensus • Unreliable science

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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-

12. 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

13. 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

14. 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. Stepped Art Fig. 2-4

15. 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

16. 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

17. 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

18. Visible light Shorter wavelengths and higher energy Longer wavelengths and lower energy Infrared radiation Gamma rays UV radiation TV, Radio waves X rays Microwaves Wavelengths (not to scale) Nanometers Micrometers Centimeters Meters Fig. 2-6

19. 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

20. 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

21. 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

22. 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

23. Life Is Organized Within Populations, Communities, and Ecosystems • Population • Genetic diversity • Habitat • Biological community (community) • Ecosystem • Biosphere

24. 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 The fundamental structural and functional unit of life Cell 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 Hydrogen Oxygen Fig. 2-8

25. Earth’s Life-Support System Has Four Major Components • Atmosphere • Troposphere: inner layer • Stratosphere: contains ozone layer • Hydrosphere • Geosphere • Biosphere • Biomes • Aquatic life zones

26. Atmosphere Biosphere (living organisms) Soil Rock Crust Mantle Geosphere (crust, mantle, core) Mantle Core Atmosphere (air) Hydrosphere (water) Fig. 2-9

27. 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

28. 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

29. 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

30. Oxygen (O2) Precipitation Carbon dioxide (CO2) Producer Secondary consumer (fox) Primary consumer (rabbit) Producers Water Decomposers Soluble mineral nutrients Fig. 2-11

31. 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

32. 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

33. Decomposers Detritus feeders Carpenter ant galleries Termite and carpenter ant work Bark beetle engraving Long-horned beetle holes Dry rot fungus Wood reduced to powder Mushroom Time progression Powder broken down by decomposers into plant nutrients in soil Fig. 2-13

34. Solar energy Chemical nutrients (carbon dioxide, oxygen, nitrogen, minerals) Heat Heat Heat Producers (plants) Decomposers (bacteria, fungi) Consumers (plant eaters, meat eaters) Heat Heat Fig. 2-14

35. Science Focus: Many of the World’s Most Important Species Are Invisible to Us • Microbes (microorganisms) • Bacteria • Protozoa • Fungi • Floating phytoplankton

36. 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

37. 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

38. 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

39. Humans Sperm whale Blue whale Elephant seal Crabeater seal Killer whale Leopard seal Adelie penguin Emperor penguin Petrel Squid Fish Carnivorous zooplankton Herbivorous zooplankton Krill Phytoplankton Fig. 2-17

40. 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

41. Usable energy available at each trophic level (in kilocalories) Heat Tertiary consumers (human) 10 Heat Secondary consumers (perch) 100 Heat Decomposers Heat Primary consumers (zooplankton) 1,000 Heat 10,000 Producers (phytoplankton) Stepped Art Fig. 2-18

42. 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

43. Fig. 2-19

44. 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

45. The Water Cycle • Major processes • Evaporation • Precipitation • Transpiration • Natural renewal of water quality

46. 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

47. Condensation Ice and snow Condensation Transpiration from plants Precipitation to land Evaporation of surface water Runoff Evaporation from ocean Lakes and reservoirs Runoff Precipitation to ocean Increased runoff on land covered with crops, buildings and pavement Infiltration and percolation into aquifer Increased runoff from cutting forests and filling wetlands Runoff Groundwater in aquifers Overpumping of aquifers Water pollution Runoff Ocean Natural process Natural reservoir Human impacts Natural pathway Pathway affected by human activities Fig. 2-20

48. The Carbon Cycle • Link between photosynthesis in producers and aerobic respiration in producers, consumers, and decomposers • Circulates carbon in the biosphere

49. Carbon dioxide in atmosphere Respiration Photosynthesis Animals (consumers) Burning fossil fuels Diffusion Forest fires Plants (producers) Deforestation Respiration Transportation Carbon in plants (producers) Carbon in animals (consumers) Carbon dioxide dissolved in ocean Marine food webs Producers, consumers, decomposers Carbon in fossil fuels Decomposition Carbon in limestone or dolomite sediments Compaction Process Reservoir Pathway affected by humans Natural pathway Fig. 2-21

50. 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