About the GED Science Exam

Questions of this type could require you to: ■ interpret results ■ draw conclusions based on results ■ analyze experimental flaws or logical fallacies in arguments ■ make a prediction ba

 W h a t t o E x p e c t o n t h e G E D S c i e n c e Te s t

The science portion of the GED consists of 50 multiple-choice questions designed to evaluate your

understand-ing of general science concepts Each question is followed by five answer choices labeled a through e You will be

instructed to select the best answers to the question There is no penalty for guessing You will have 80 minutes (one hour and 20 minutes) to answer the questions on this part of the exam There will be some question sets— i.e., more than one question will be asked about a particular graphic or passage

Types of Questions

On the test, you will encounter 25 conceptual understanding and 25 problem-solving questions.

A question that tests your conceptual understanding requires you to show your understanding of the material

presented as a part of the question In this type of question, you could be asked to:

■ read a graphic

■ summarize the results of an experiment

■ rephrase a fact or an idea described in a passage

■ find supporting detail in a passage

■ make a generalization about information presented in the question

■ understand cause and effect

C H A P T E R

About the GED Science Exam

TO PREPARE effectively for the GED Science Exam, you need to

know exactly what the test is like This chapter explains the structure

of the exam, including the types of questions you will be asked and the topics that will be tested

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Problem-solving questions will ask you to apply your

understanding of information presented as part of the

question Questions of this type could require you to:

■ interpret results

■ draw conclusions based on results

■ analyze experimental flaws or logical fallacies in

arguments

■ make a prediction based on information

pro-vided in the question

■ select the best procedure or method to

accom-plish a scientific goal

■ select a diagram that best illustrates a principle

■ apply scientific knowledge to everyday life

■ use the work of renowned scientists to explain

everyday global issues

Some questions will require you to draw on

knowl-edge you have acquired through your daily life and prior

schooling In other questions, all the necessary

informa-tion will be included in the passage or graphic provided

as part of the question In either case, reviewing basic

sci-ence concepts presented in the following chapters and

answering as many practice questions as you can will

improve your performance

About half the problems on the GED Science Exam

will require you to understand, interpret, or apply

infor-mation presented in graphical form Graphical

informa-tion includes diagrams, charts, and graphs Graphics are

a concise and organized way of presenting information

Once you realize that all graphics have some common

basic elements, it will not matter whether their

informa-tion presented is in the area of biology, chemistry,

physics, or Earth science

D IAGRAMS

Diagrams can be used to show a sequence of events, a

chemical or biological process, the setup of a science

experiment, a phenomenon, the relationship between

different events or species, and so forth Here are some

examples that you can look up in your science textbooks:

■ diagram of an electrochemical cell (physical

science)—process

■ diagram of the phases of cell division (life

science)—sequence of events

■ pedigree diagram for color blindness (life

■ diagrams showing the oxygen and nitrogen cycle (Earth and space science)—process

■ diagram showing the repulsion of like charges (physical science)—phenomenon

■ diagram illustrating the titration technique (chemistry)—setup of an experiment

When you see a diagram, first ask yourself what its purpose is: What is it trying to illustrate? Then look at the different labeled parts of the diagram What is their function? How are they interrelated?

C HARTS

All charts are composed of rows (horizontal) and columns (vertical) Entries in a single row of a table usu-ally have something in common, and so do entries in a single column Two common questions about charts involve reading an entry and finding a trend Is there a change? Do the numbers increase? Decrease?

G RAPHS

The most common types of graphs are scatter plots, bar graphs, and pie graphs Whenever a variable depends continuously on another variable, this dependence can

be visually represented in a scatter plot An example of data that can be represented on a scatter plot is popula-tion growth as a funcpopula-tion of time A scatter plot consists

of the horizontal (x) axis, the vertical (y) axis, and col-lected data points for variable y, measured at variable x.

A graph often contains a legend, especially if there is more then one data set or more than one variable A leg-end is a key for interpreting the graph It lists the symbols used to label a particular data set

Bar graphs are similar to scatter plots Both have a

variable y plotted against a variable x However, in bar

graphs, data is represented by bars, rather than by points Bar graphs are often used to indicate an amount or level,

as opposed to a continuous change You may have seen bar graphs on your family’s utility bill Utility companies often plot the amount of energy used by an average con-sumer during different months of the year

Pie graphs are used to show what percent of a total is taken up by different components of that whole For example, a pie chart could be used to show the percent of science students who major in chemistry, physics, biol-ogy, geolbiol-ogy, and astronomy

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Test Topics

The topics covered on the GED Science Exam are:

■ physical science—35% of the questions

■ life science—45% of the questions

■ Earth and space science—20% of the questions

On the GED, physical science includes high school

physics and chemistry and covers the structure of

atoms, the properties of matter, chemical reactions,

con-servation of mass and energy, increase in disorder, the

laws of motion, forces, and the interactions of energy

and matter

Life science deals with subjects covered in high school

biology classes, including cell structure, heredity,

bio-logical evolution, behavior, and interdependence of

organisms

Earth and space science GED questions will test your

knowledge of the Earth and solar system, the

geochem-ical cycles, the origin and evolution of the Earth, and the

universe

Recent Changes in the GED

In accordance with Education Standards set forth by the

National Academy of Sciences, the GED Science Test has

been modified to include more interdisciplinary

ques-tions These questions also fall into one of the three

major categories (physical science, life science, and Earth

and space science) but focus on themes common to all

sciences Common themes include the scientific method,

the organization of knowledge, applications in

technol-ogy and everyday situations, and the development of

sci-entific ideas through history Since 50% of the GED

Science questions will be interdisciplinary, a chapter will

cover each of the following themes:

■ unifying concepts and processes

■ science as inquiry

■ science and technology

■ science and personal and social perspectives

■ history and nature of science

Unifying concepts and processes in science include

the organization of scientific knowledge, development of scientific models based on experimental evidence, equi-librium, change, conservation, measurement, and rela-tionship between form and function Approximately two questions on the GED Science Exam will fall into this category

Science as inquiry questions can require you to

sum-marize and interpret experimental results, select relevant information, understand and apply the scientific method, make a prediction or draw a conclusion based

on given facts, and evaluate the source of experimental flaws and error There will be about seven questions of this type on the GED

Science and technology questions require you to

understand the function of an instrument, instructions for operating an instrument, technological processes, the elements of technological design, how technology uses scientific knowledge to improve products and processes, and the impact of technology on science, human life, and environment About three questions of this type will appear on the test

Science and personal and social perspectives

ques-tions include quesques-tions on human health (nutrition, exercise, disease prevention, genetics), climate, pollution, population growth, natural resources, social impact of natural disasters, human-induced environmental haz-ards, public policy, application of scientific knowledge to everyday situations, and application of scientific knowl-edge to explain global phenomena These questions are quite common You can expect to see about nine of them

on the GED

History and nature of science questions could

include a passage on the development of an idea or the-ory through time, or the work of an important scientist You could also expect to see general questions about the development of science as a field and its principles You will probably see about three questions of this type on the GED

The chart on the next page summarizes the approxi-mate breakdown of question types and subjects covered

in the questions on the GED Science Exam

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GED SCIENCE EXAM

50 QUESTIONS, 80 MINUTES

Type: 25 conceptual understanding questions, 25 problem-solving questions

Format: 25 short paragraph questions, 25 questions based on a passage or graphic

Subject: 45% life science questions, 35% physical science questions, 20% Earth and space science questions Content: 25 fundamental science (life, physical, Earth/space) questions, 25 interdisciplinary questions

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In addition to the interdisciplinary questions, other

recent changes to the GED Science Exam include:

■ increased focus on environmental and health

top-ics (recycling, heredity, prevention of disease,

pol-lution, and climate)

■ increased focus on science as found in daily life

■ increased number of single-item questions

■ decreased number of questions based on the

same passage/graphic

Now that you have a better idea of the kind of ques-tions that may appear on the GED Science Exam, you can start reviewing the basic science concepts described

in the next chapters

WH E T H E R T H E Y A R E chemists, biologists, physicists, or geologists, all scientists seek to

organ-ize the knowledge and observations they collect They look for evidence and develop models

to provide explanations for their observations Scientists depend heavily on measurement and developed devices and instruments for measuring different properties of matter and energy Scientists also use units to make the quantities they measure understandable to other scientists Questions that come up in every science are:

■ What causes change?

■ What causes stability?

■ How does something evolve?

■ How does something reach equilibrium?

■ How is form related to function?

 S y s t e m s , O r d e r, a n d O r g a n i z a t i o n

What happens when an Internet search produces too many results? Clearly, having some results is better than hav-ing none, but havhav-ing too many can make it difficult to find the necessary information quickly If scientists didn’t systematically organize and order information, looking for or finding a piece of data or making a comparison

C H A P T E R

Unifying Concepts and Processes

THIS CHAPTER will review some of the unifying concepts and

processes in science You will learn the questions and themes that are common to each of the scientific disciplines and how scientists seek

to answer those questions

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would be as difficult as looking for one specific book in a

huge library in which the books are randomly shelved In

every science, knowledge is grouped into an orderly

manner

In biology, an organism is classified into a domain,

kingdom, phylum, class, order, family, genus, and species

Members of the same species are the most similar All

people belong to the same species People and monkeys

belong to the same order People and fish belong to the

same kingdom, and people and plants share the same

domain This is an example of hierarchical

classifica-tion—each level is included in the levels above Each

species is part of an order, and each order is part of a

kingdom, which is a part of domain

Another example of hierarchical classification is your

address in the galaxy It would include your house

num-ber, street, city, state, country, continent, planet, star

sys-tem, and galaxy

Here is another example of organization in biology

Each organism is made of cells Many cells make up a

tis-sue Several tissues make up an organ Several organs

make up an organ system

In chemistry, atoms are sorted by atomic number in

the periodic table Atoms that have similar properties are

grouped

Scientists also classify periods of time since Earth’s

formation 4.6 billion years ago, based on the major

events in those eras Time on Earth is divided into the

following eras: Precambrian, Paleozoic, Mesozoic, and

Cenozoic The eras are further divided into periods, and

the periods into epochs

 E v i d e n c e, M o d e l s , a n d

E x p l a n a t i o n

Scientists look for evidence The job of a scientist is to

observe and explain the observations using factual

evi-dence, and develop models that can predict unobserved

behavior

Scientific evidence should:

■ be carefully documented and organized

■ be quantified as much as possible

■ be reproducible by other scientists

Scientific explanations should:

■ be consistent with observations and evidence

■ be able to predict unobserved behavior

■ be internally consistent (two statements in the same explanation should not contradict each other)

Scientific models should:

■ be consistent with observations

■ be consistent with explanations

■ be able to predict unobserved behavior

■ cover a wide range of observations or behaviors

 E q u i l i b r i u m a n d C h a n g e

A favorite pastime of scientists is figuring out why things change and why they stay the same On one hand, many systems seek to establish equilibrium In organisms, this

equilibrium is called homeostasis It is the tendency of

organisms to maintain a stable inner environment, even when the outside environment changes When people sweat, they are trying to cool off and maintain their equi-librium temperature

Contrary to a common misconception, equilibrium is not a state of rest at which nothing happens At chemi-cal equilibrium, reactants continue to form products, and products continue to form reactants However, the rate of formation of reactants is the same as the rate of formation of products, so that no net change is observed Equilibria are fragile states, and a little change, a tiny force, is often enough to disturb them Think of a seesaw

in balance A little puff of wind, and the balance is gone The same is true of chemical equilibrium—increase the pressure or temperature, and the equilibrium will shift Your body is pretty good at keeping a steady tempera-ture, but when you get sick, you are thrown off balance;

up goes your temperature, and out the window goes your homeostasis

Systems at equilibrium appear to be stable and con-stant But a small disturbance is often enough to change

an equilibrium state The reason for change in a system is reestablishing equilibrium or reaching a more stable state

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A change is often a response to a gradient or a

differ-ence in a property in two parts of a system Here are

some examples of common gradients and the changes

they drive

■ Difference in temperature—causes heat to flow

from hotter object (region) to colder object

(region)

■ Difference in pressure—causes liquid (water) or

gas (air) to flow from region of high pressure to

region of low pressure

■ Difference in electric potential—causes electrons

to flow from high potential to low potential

■ Difference in concentration—causes matter to

flow until concentrations in two regions are

equalized

 M e a s u r e m e n t

An established principle in science is that observations should be quantified as much as possible This means that rather than reporting that it’s a nice day out, a

scien-tist needs to define this statement with numbers By nice,

two different people can mean two different things Some like hot weather Some like lots of snow But giving the specifics on the temperature, humidity, pressure, wind speed and direction, clouds, and rainfall allows

everyone to picture exactly what kind of a nice day we

are having

For the same reason, a scientist studying the response

of dogs to loud noise wouldn’t state that the dog hates it when it’s loud A scientist would quantify the amount of noise in decibels (units of sound intensity) and carefully note the behavior and actions of the dog in response to the sound, without making judgment about the dog’s deep feelings Now that you are convinced that quantify-ing observations is a healthy practice in science, you will probably agree that instruments and units are also useful

In the table at the bottom of the page are the most common properties scientists measure and common units these properties are measured in You don’t need to

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COMMON UNITS OF MEASURE

centimeter (about half an inch) micrometer (about the size of a cell) nanometer (often used for wavelengths of light) angstrom (about the size of an atom)

kilometer (about half a mile) light-year (used for astronomical distances)

Volume milliliter (about a teaspoon), liter (about 1 4 of a gallon)

memorize these, but you can read them to become

acquainted with the ones you don’t already know

You should also be familiar with the following devices

and instruments used by scientists:

■ balance: for measuring mass

■ graduated cylinder: for measuring volume

(always read the mark at the bottom of the

curved surface of water)

■ thermometer: for measuring temperature

■ voltmeter: for measuring potential

■ microscope: for observing very small objects,

such as cells

■ telescope: for observing very distant objects, such

as other planets

 E v o l u t i o n

Most students tend to associate evolution with the

bio-logical evolution of species However, evolution is a series

of changes, either gradual or abrupt, in any type of

sys-tem Even theories and technological designs can evolve

Ancient cultures classified matter into fire, water,

earth, and air This may sound naive and funny now, but it

was a start The important thing was to ask what is matter,

and to start grouping different forms of matter in some

way As more observations were collected, our

under-standing of matter evolved We started out with air, fire,

earth, and water, and got to the periodic table, the structure

of the atom, and the interaction of energy and matter

Consider how the design of cars and airplanes has

changed over time Think of a little carriage with

crooked wheels pulled by a horse and the plane with

pro-pellers The car and the plane have evolved as well

So did our planet According to theory, 200 million

years ago, all the present continents formed one

super-continent Twenty million years later, the supercontinent

began to break apart The Earth is still evolving,

chang-ing through time, as its plates are still movchang-ing and the

core of the Earth is still cooling

 F o r m a n d F u n c t i o n

There is a reason why a feather is light as a feather In both nature and technology, form is often related to function A bird’s feathers are light, enabling it to fly more easily Arteries spread into tiny capillaries, increas-ing the surface area for gas exchanged Surface area and surface-to-volume ratio are key issues in biology and chemistry A cell has a relatively large surface-to-volume ratio If it were larger, this ratio would increase Through the surface, the cell regulates the transport of matter in and out of the cell If the cell had a bigger volume, it would require more nutrients and produce more waste, and the area for exchange would be insufficient Notice the difference between the leaves of plants that grow in hot, dry climates and the leaves of plants in cooler, wet-ter climates What function do the differences in form serve? Did you realize that a flock of birds tends to fly forming the “V” shape, much like the tip of an arrow? Several years ago, curved skis were brought onto the market and have almost replaced traditional straight-edge skis There are countless examples of how form develops to serve a useful function Your job is to open your eyes to these relationships and be prepared to make the connections on the GED Science Exam

This chapter has shown that there are common threads in all areas of science and that scientists in dif-ferent disciplines use similar techniques to observe the patterns and changes in nature Try to keep these key principles in mind, since they are bound to reappear— not only on the GED, but in your daily life as well

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AL L S C I E N C E S A R E the same in the sense that they involve the deliberate and systematic

observa-tion of nature Each science is not a loose branch The branches of science connect to the same root

of objective observation, experiments based on the scientific method, and theories and conclusions based on experimental evidence An advance in one branch of science often contributes to advances in other sci-ences, and sometimes to entirely new branches For example, the development of optics led to the design of a microscope, which led to the development of cellular biology

 A b i l i t i e s N e c e s s a r y f o r S c i e n t i f i c I n q u i r y

A good scientist is patient, curious, objective, systematic, ethical, a detailed record keeper, skeptical yet open-minded, and an effective communicator While certainly many scientists don’t posses all these qualities, most strive to obtain or develop them

C H A P T E R

Science as Inquiry

WHATEVER THEIR discipline, all scientists use similar methods

to study the natural world In this chapter, you will learn what abilities are necessary for scientific inquiry and what lies at the root of all science

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Patience is a virtue for any person, but it is essential for

a person who wants to be a scientist Much of science

involves repetition: repetition to confirm or reproduce

previous results, repetition under slightly different

con-ditions, and repetition to eliminate an unwanted

vari-able It also involves waiting—waiting for a liquid to boil

to determine its boiling point, waiting for an animal to

fall asleep in order to study its sleep pattern, waiting for

weather conditions or a season to be right, etc Both the

repetition and the waiting require a great deal of

patience Results are not guaranteed, and a scientist often

goes through countless failed attempts before achieving

success Patience and the pursuit of results in spite of

dif-ficulties are traits of a good scientist

Curiosity

Every child asks questions about nature and life In some

people, this curiosity continues throughout adulthood,

when it becomes possible to work systematically to

sat-isfy that curiosity with answers Curiosity is a major drive

for scientific research, and it is what enables a scientist to

work and concentrate on the same problem over long

periods of time It’s knowing how and why, or at least

part of the answer to these questions, that keeps a

scien-tist in the lab, on the field, in the library, or at the

com-puter for hours

Objectivity

Objectivity is an essential trait of a true scientist By

objectivity, we mean unbiased observation A good

sci-entist can distinguish fact from opinion and does not let

personal views, hopes, beliefs, or societal norms interfere

with the observation of facts or reporting of

experimen-tal results An opinion is a statement not necessarily

sup-ported by scientific data Opinions are often based on

personal feelings or beliefs and are usually difficult, if not

impossible to measure and test A fact is a statement

based on scientific data or objective observations Facts

can be measured or observed, tested, and reproduced A

well-trained scientist recognizes the importance of

reporting all results, even if they are unexpected,

unde-sirable, or inconsistent with personal views, prior

hypotheses, theories, or experimental results

Systematic Study

Scientists who are effective experimentalists tend to work systematically They observe each variable inde-pendently, and develop and adhere to rigorous experi-mental routines or procedures They keep consistent track of all variables and systematically look for changes

in those variables The tools and methods by which changes in variables are measured or observed are kept constant All experiments have a clear objective Good scientists never lose track of the purpose of their exper-iment and design experexper-iments in such a way that the amount of results is not overwhelming and that the results obtained are not ambiguous The scientific method, described later in this chapter, forms a good basis for systematic research

Record Keeping

Good record keeping can save scientists a lot of trouble Most scientists find keeping a science log or journal help-ful The journal should describe in detail the basic assumptions, goals, experimental techniques, equip-ment, and procedures It can also include results, analy-sis of results, literature references, thoughts and ideas, and conclusions Any problem encountered in the labo-ratory should also be noted in the journal, even if it is not directly related to the experimental goals For example, if there is an equipment failure, it should be noted Con-ditions that brought about the failure and the method used to fix it should also be described It may not seem immediately useful, but three years down the road, the same failure could occur Even if the scientist recollected the previous occurrence of the problem, the details of the solution would likely be forgotten and more time would

be needed to fix it But looking back to the journal could potentially determine the problem and provide a solu-tion much more quickly Scientific records should be clear and readable, so that another scientist could follow the thoughts and repeat the procedure described Records can also prove useful if there is a question about intellectual property or ethics of the researcher

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