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 law Well-accepted pattern in data Propose an hypothesis to explain data Analyze data (check for patterns) Ask a question to be investigated Find out what is known about the problem (literature search) Fig. 2-1, p. 22 Identify a problem Perform an experiment to answer the question and collect data Use hypothesis to make testable predictions Perform an experiment to test predictions Scientific theory Well-tested and widely accepted hypothesis Accept hypothesis Revise hypothesis Test predictions Make testable predictions 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 Unique properties Cannot 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 (n 0 ) 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 Bananas Tomatoes Typical rainwater Bread 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 detergents Baking 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 Atoms Molecules Macromolecules Organelles

Organization of Life CellsTissuesOrgans Organ Systems Organism

Organization of Life PopulationCommunity Ecosystem Biosphere

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 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. 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 power plant 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.