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 Effective Communication Reading scientific journals, collaborating with other sci- entists, going to conferences, and publishing scientific papers and books are basic elements of communication in the science community. Scientists benefit from explor- ing science literature because they can often use tech- niques, results, or methods published by other scientists. In addition, new results need to be compared or con- nected to related results published in the past, so that someone reading or hearing about the new result can understand its impact and context. As many scientific branches have become interdisci- plinary, collaboration among scientists of different backgrounds is essential. For example, a chemist may be able to synthesize and crystallize a protein, but analyzing the effect of that protein on a living system requires the training of a biologist. Rather than viewing each other as competitors, good scientists understand that they have a lot to gain by collaborating with scientists who have dif- ferent strengths, training, and resources. Presenting results at scientific conferences and in science journals is often a fruitful and rewarding process. It opens a scien- tific theory or experiment to discussion, criticism, and suggestions. It is a ground for idea inception and exchange in the science community. Scientists also often need to communicate with those outside the scientific community—students of science, public figures who make decisions about funding science projects, and journalists who report essential scientific results to the general audience. 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 dif- ferent explanations and look for holes in reasoning or experimental inconsistencies. They come up with tests that a theory should pass if it is valid. They think of ways in which an experiment can be improved. This is not done maliciously. The goal is not to discredit other researchers, but to come up with good models and an understanding of nature. Unreasonable skepticism, however, is not very useful. There is a lot of room in science for open-mindedness. If a new theory conflicts with intuition, belief, or previ- ous established theories, but is supported by rigorously developed experiments and can be used to make accurate predictions, refusal to accept its validity is stubbornness, rather than skepticism. Ethics Consider a chemist in the pharmaceutical company who, after much effort, designs a chemical that can cure brain tumors without affecting healthy brain cells. No doubt the scientist is excited about this result and its potential positive impact on humanity. Once in a while, however, experimental rats given this drug die from heart failure within minutes after the drug is administered. But since it happens only occasionally, the scientist assumes that it’s only a coincidence, and that those rats that died had heart problems and would have died anyway. The scien- tist doesn’t report these few cases to the supervisor, and assumes that if it’s a serious problem, the FDA (Food and Drug Administration) would discover it, and nobody would get hurt. While the scientist has good intentions, such as making the benefits of the new drug available to people who need it, failing to report and further investi- gate the potential adverse effects of the drug constitutes negligent and unethical behavior. Scientists are expected to report data without making up, adjusting, downplaying, or exaggerating results. Sci- entist 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. Understandings about Scientific Inquiry Why study science? A scientist seeks to observe, under- stand, or control the processes and laws of nature. Sci- entists assume that nature is governed by orderly principles. They search for these principles by making observations. The job of a scientist is to figure out how something works, or to explain why it works the way it does. Looking for a pattern, for cause and effect, expla- nation, improvement, developing theories based on experimental results are all jobs of a scientist. – SCIENCE AS INQUIRY– 219 The Scientific Method There are many ways to obtain knowledge. Modern sci- entists 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 answer- ing 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 study, and we will review those concepts in this section. The scientific method involves: ■ asking a specific question about a process or phe- nomenon that can be answered by performing experiments ■ formulating a testable hypothesis based on obser- vations 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 and is consistent with experimental results ■ making predictions based on the model or theory in order to test it and designing experiments that could disprove the proposed theory THE QUESTION In order to understand something, a scientist must first focus on a specific question or aspect of a problem. In order to do that, the scientist has to clearly formulate the question. The answer to such a question has to exist and the 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 experi- ment. 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, such as “How do animals obtain food?” is not very useful for gaining knowledge. This question is too general and broad for one person to answer. Better questions are more specific—for example, “Does each member of a wolf pack have a set responsi- bility or job when hunting for food?” A question that is too general and not very useful is “Why do some people have better memories than others?” A better, more spe- cific question, along the same lines, is “What parts of the brain and which brain chemicals are involved in recol- lection of childhood memories?” A good science question is very specific and can be answered by performing experiments. THE HYPOTHESIS After formulating a question, a scientist gathers the information on the topic that is already available or pub- lished, 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 phe- nomenon is called a hypothesis. A hypothesis doesn’t have to be correct, but it should be testable. In other words, a testable hypothesis can be disproved through experiment, in a reasonable amount of time, with the resources available. For example, the statement, “Everyone has a soul mate somewhere in the world,” is not a valid hypothesis. First, the term soul mate is not well defined, so formulating an experiment to determine whether two people are soul mates would be difficult. More importantly, even if we were to agree on what soul mate means and how to experimentally deter- mine whether two people are soul mates, this hypothe- sis could never be proved wrong. Any experiment conceived would require testing every possible pair of human beings around the world, which, considering the population and the population growth per second, is just not feasible. A hypothesis doesn’t need to be correct. It only has to be testable. Disproving a hypothesis is not a failure. It casts away illusions about what was previously thought to be true, and can cause a great advance, a thought in another direction that can bring about new ideas. Most likely, in the process of showing that one hypothesis is wrong, a – SCIENCE AS INQUIRY– 220 . reappear— not only on the GED, but in your daily life as well. – UNIFYING CONCEPTS AND PROCESSES– 2 16 A LL SCIENCES ARE the same in the sense that they involve the deliberate and systematic observa- tion