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.