About the GED Science Exam

 What to Expect on the GED Science Test 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 CHAPTER 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. 20 209 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 science)—relationship between events ■ 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 function 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, geology, and astronomy. – ABOUT THE GED SCIENCE EXAM – 210 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 questions 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. – ABOUT THE GED SCIENCE EXAM – 211 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 – ABOUT THE GED SCIENCE EXAM – 212 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. W HETHER THEY ARE 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?  Systems, Order, and Organization What happens when an Internet search produces too many results? Clearly, having some results is better than hav- ing none, but having 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 CHAPTER 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. 21 213 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.  Evidence, Models, and Explanation 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  Equilibrium and Change 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. – UNIFYING CONCEPTS AND PROCESSES – 214 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.  Measurement 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 – UNIFYING CONCEPTS AND PROCESSES – 215 COMMON UNITS OF MEASURE Length or distance meter (about a yard) 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) Time second, hour, year, century Volume milliliter (about a teaspoon), liter (about ᎏ 1 4 ᎏ of a gallon) Temperature degree Celsius, degree Fahrenheit, or Kelvin Charge coulomb Electric potential volt Pressure atmosphere, mm of Hg, bar Force newton 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  Evolution 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 moving and the core of the Earth is still cooling.  Form and Function 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. – UNIFYING CONCEPTS AND PROCESSES – 216 A LL SCIENCES ARE 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.  Abilities Necessary for Scientific Inquiry 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. CHAPTER 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. 22 217 Patience 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 experiments 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. – SCIENCE AS INQUIRY – 218 [...]... T HE H YPOTHESIS After formulating a question, a scientist gathers the information on the topic that is already available or published, and then comes up with an educated guess or a tentative explanation about the answer to the question Such an educated guess about a natural process or phenomenon is called a hypothesis A hypothesis doesn’t have to be correct, but it should be testable In other words,... scientists tend to obtain knowledge about the world by making systematic observations This principle is called empiricism and is the basis of the scientific method The scientific method is a set of rules for asking and answering questions about science Most scientists use the scientific method loosely and often unconsciously However, the key concepts of the scientific method are the groundwork for scientific... for trends in the data and correlation among variables It also involves making generalizations about the results, quantifying experimental error, and correlating the variable being manipulated to the variable being tested A scientist who analyzes results unifies them, interprets them, and gives them meaning The goal is to find a pattern or sense of order in the observations and to understand the reason... pieces of information Eliminating a potential hypothesis narrows down the choices, and eliminating the wrong answers sometimes leads to finding the correct one T HE E XPERIMENT In an experiment, researchers manipulate one or more variables and examine their effect on another variable or variables An experiment is carefully designed to test the hypothesis The number of variables in an experiment should... groups of patients are examined One is given the drug, one is given a placebo (a pill containing no active ingredient), and one is not given anything This is a good way to test whether the improvement in patient condition (observed variable) is due to the active ingredient in the pill (manipulated variable) If the patients in the group that was given the placebo recover sooner or at the same time as those... possibility of obtaining it through experiment must exist For example, the question “Does the presence of the moon shorten the life span of ducks on Earth?” is not valid because it can not be answered through experiment There is no way to measure the life span of ducks on Earth in the absence of the moon, since we have no way of removing the moon from its orbit Similarly, asking a general question,... predictions based on their models and theories A good theory or model should be able to accurately predict an event or behavior Many scientists go a step beyond and try to test their theories by designing experiments that could prove them wrong The theories that fail to make accurate predictions are revised or discarded, and those that survive the test of a series of experiments aimed to prove them wrong become... section The scientific method involves: ■ ■ ■ ■ ■ ■ asking a specific question about a process or phenomenon that can be answered by performing experiments formulating a testable hypothesis based on observations and previous results designing an experiment, with a control, to test the hypothesis collecting and analyzing the results of the experiment developing a model or theory that explains the phenomenon... are also expected to not take credit for work they didn’t do, to obey environmental laws, and to consider and understand the implications of use of scientific knowledge they bring about Skepticism and Open-Mindedness Scientists are trained to be skeptical about what they hear, read, and observe Rather than automatically accept the first proposed explanation, they search for different explanations and look... sooner or at the same time as those who were given the drug, the effect of pill taking can be attributed patient belief that a pill makes one feel better, or to other ingredients in the pill If the group that was not given any pill recovers faster or just as fast as the group that was given the drug, the improvement in patient condition could be a result of the natural healing processes T HE A NALYSIS Analysis . THE GED SCIENCE EXAM – 210 Test Topics The topics covered on the GED Science Exam are: ■ physical science 35% of the questions ■ life science 45% of the. question types and subjects covered in the questions on the GED Science Exam. – ABOUT THE GED SCIENCE EXAM – 211 GED SCIENCE EXAM 50 QUESTIONS, 80 MINUTES Type: