Student Success Guide TO ACCOMPANY WHAT IS LIFE? A GUIDE TO BIOLOGY WITH PHYSIOLOGY Third Edition by Jay Phelan Meredith S. Norris, M.S. Jennifer M. Warner, Ph.D. Department of Biology The University of North Carolina at Charlotte W.H. Freeman and Company A Macmillan Education Company New York 2009, 2013, 2015 by W.H. Freeman and Company www.whfreeman.com USED BY PERMISSION
2 Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World Chapter 1 SCIENTIFIC THINKING YOUR BEST PATHWAY TO UNDERSTANDING THE WORLD Learning Objectives Differentiate between scientific and alternative ways of thinking Describe the attributes of scientific and biological literacy Apply the scientific method to everyday situations Understand the flexibility of the scientific method Describe the attributes of the scientific method that allow it to be an effective tool Design critical experiments to test hypotheses Define scientific theory Understand the importance of well-designed and controlled experiments Describe ways to blind experiments Describe the biases that can occur in scientific studies and ways to reduce those biases Understand how statistics can add support to scientific claims Identify pseudoscience and anecdotal evidence masked as scientific evidence Understand the limitations of science as a means to answer questions Understand how hierarchical organization and evolution tie together all the major themes in biology Chapter Outline I. More Than Just a Collection of Facts, Science Is a Process for Understanding the World Define science: Define biology: Define scientific literacy:
Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World 3 The development of biological literacy is important for understanding social, political, medical, and legal issues. This involves the ability to: 1. 2. 3. How is superstition different from scientific thinking? Explain. In the most straightforward terms, the scientific method is a process of: Describe empirical knowledge: Provide two examples of non-scientific ways of thinking. 1. 2. II. A Beginner s Guide: What Are the Steps of the Scientific Method?
4 Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World While some people envision scientists in labs checking off the steps of the scientific method as they work, in reality the scientific method is more of a flexible set of guidelines for scientific thinking. The basic steps in the method include: 1. 2. 3. 4. 5. Describe what is meant by the term self-correcting in reference to the scientific method: A is defined as tentative explanation for observed phenomena. A useful hypothesis must be able to achieve two goals: 1. 2. A hypothesis that is stated such that there is not a relationship between two variables is referred to as a hypothesis. In terms of hypotheses, it is best to state that they can be by data instead of proven. Useful hypotheses involve testable predictions. Hypotheses can be refined and adjusted as needed. An experiment that makes it possible to support or disprove a hypothesis is called a experiment. Explain how a placebo is used in a critical experiment.
Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World 5 Drawing conclusions from experimentation provides opportunity for revision. In your own words explain why it is important to include revision in this process. Hypotheses with overwhelming experimental support can evolve into theories. While the common use of the term theory refers to a hunch or tentative hypothesis, the scientific use of theory means something much more concrete with extensive empirical evidence to support the theory. III. Well-Designed Experiments Are Essential to Testing Hypotheses Experimental design is a critical part of the scientific process. Experiments that are carefully and purposefully designed are most likely to show cause-and-effect relationships between variables. Additionally, it is critical that experimental results can be reproduced when the experiment is repeated. A. Controlled Experiments Define each of the following elements of experiments: 1. Treatment 2. Experimental group 3. Control group 4. Variables Why is it so important to control variables in an experiment? The use of placebos can lead to the placebo effect. Explain what this means.
6 Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World Blinding is a way to reduce bias in reporting and analyzing data. In a blind experimental design, the are not aware whether they are receiving the treatment or not. In a double-blind experimental design, neither the nor the are aware of which subjects are receiving the treatment. Blinded experimental designs can also been improved by randomizing the study. What does this mean? B. A Randomized, Well-Controlled Study: Is arthroscopic surgery for arthritis of the knee beneficial? Did this study utilize a blinded experimental design? Explain. Although this particular study would not be an easy one to replicate, explain why scientific studies should have an expectation of reproducible results. Give an example of potential bias that could have influenced the outcome(s) of this study if it was designed differently. IV. Scientific Thinking Can Help Us Make Wise Decisions The use of the scientific method and a critical approach to reviewing evidence can help us make sense of data and anecdotal evidence, as well as help us distinguish science from pseudoscience.
Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World 7 A. Visual Displays of Data Which forms of displaying data are used most frequently in biology? Describe each of the common elements found in most visual displays of data: 1. Title 2. x-axis 3. y-axis 4. Independent variable 5. Dependent variable 6. Data points B. Statistics How can statistics put data in context to determine if a hypothesis is supported or not? When evaluating statistical analysis of data in order to determine whether the treatment had a significant effect or not, we are looking for a difference between the experimental and control groups with a variation within each group. Correlational studies look at relationships between different variables. A correlation is when an increase in one variable leads to an increase in another variable. A correlation occurs when an increase in one variable leads to a decrease in another variable.
8 Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World C. Pseudoscience and Anecdotal Evidence People are often taken in by false scientific claims. The two most common ways to mislead the public are by using pseudoscience and anecdotal evidence. Describe what these terms mean: o Pseudoscience o Anecdotal evidence Describe an example of misleading scientific evidence in the form of pseudoscience and anecdotal evidence: o Pseudoscience o Anecdotal evidence D. The Limits of Science While we often talk about what science is, we don t always hear so much about what science is not. Science, just like other disciplines, has limitations to the sorts of questions it can answer. Give several examples of questions that science cannot answer: V. On the Road to Biological Literacy: What Are the Major Themes in Biology? Biology is the study of life. Identify the major characteristics similar to all living organisms.
Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World 9 As you progress through the course you will learn about many differing aspects of biology. However, there are two common themes that will prevail throughout the course. Explain these major themes: o Hierarchical organization o Evolution
10 Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World Testing and Applying Your Understanding Multiple Choice (For more multiple choice questions, visit www.prep-u.com.) 1. In controlled experiments: a) one variable is manipulated while others are held constant. b) all variables are held constant. c) all variables are dependent on each other. d) all variables are independent of each other. e) all critical variables are manipulated. 2. In the late 1950s, a doctor reported in the Journal of the American Medical Association that stomach ulcers could be effectively treated by having a patient swallow a balloon connected to some tubes that circulated a refrigerated fluid. He argued that, by supercooling the stomach, acid production was reduced and the ulcer relieved. All 24 of his patients who received the treatment were healed. Why does this fall short of qualifying as an example of the scientific method? a) All of the patients were aware of the treatment they received. b) There was no control group with which to compare his patients who received the treatment. c) Although there was a control group, it was not randomly selected. d) There were not enough experimental subjects to draw a definitive conclusion. e) All of the above are correct. 3. The placebo effect: a) is an urban legend. b) reveals that sugar pills are generally as effective as actual medications in fighting illness. c) demonstrates that most scientific studies cannot be replicated. d) is the frequently observed, poorly understood phenomenon that people tend to respond favorably to any treatment. e) reveals that experimental treatments cannot be proven as effective. 4. In many reptiles, the sex of a fetus is determined by the incubation temperature of the egg; higher temperatures lead to more males. However, DDE (a chemical byproduct of DDT) in the environment prior to birth drastically lowers the normal percentage of males. You want to design a good scientific experiment to illustrate this phenomenon, but before you can, you must properly identify the different components of the experiment. Which of the following choices does not properly identify each of the experimental components in this example? a) The sample size of your experiment would be the number of eggs you test on. b) The constant in this experiment would be the application of DDE. c) The experimental group would be the group of eggs you did expose to DDE prior to birth. d) The control group would be the group of eggs you did not expose to DDE prior to birth. e) All of the above are correct.
Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World 11 5. By 1796 it had been observed that milkmaids who had been exposed to cowpox did not succumb to the deadly plague of small pox that was ravishing both Europe and Britain. From this observation, Edward Jenner was able to construct the world s first successful vaccine. If you had to predict the hypothesis that Jenner made to lead him to his creation, which of the following choices best fits your prediction? a) If milkmaids exposed to cowpox are immune to smallpox, then cowpox and smallpox are the same disease. b) If exposure to cowpox gives immunity to smallpox in milkmaids, then milkmaids have a natural immunity and their blood should be used to develop a smallpox vaccine. c) If exposure to cowpox gives immunity to smallpox in milkmaids, then exposure to cowpox should give immunity to smallpox in other individuals as well. d) Cowpox and smallpox are caused by the same microorganism. e) Exposure to smallpox always gives immunity to cowpox. 6. Science as a way of seeking principles of order differs from art, religion, and philosophy in that: a) all scientific knowledge is gained by experimentation. b) science limits its search to the natural world of the physical universe. c) there is no room for intuition or guessing. d) science denies the existence of the supernatural. e) science deals exclusively with known facts. 7. Experimental drugs must undergo many rigorous trials to ensure they deliver their medical benefits effectively and safely. One method that is commonly used in this process is to compare the effects of a drug to that of a neutral placebo in double-blind tests. Which of the following choices correctly describes a double-blind test? a) The researchers apply two layers of blindfolds to the study s participants so they don t know if they are receiving the drug or a placebo. b) The researchers do not know who receives the drug or the placebo but the participants know and tell them later. c) Neither the researchers nor the study s participants know who is receiving the drug and who is receiving the placebo. d) The researchers know who is receiving the drug and who is receiving the placebo but do not know what the supposed effects of the drug should be. e) None of the above descriptions is correct. 8. Which of the following is a limitation on scientific research? a) It is difficult for scientists to fully understand their own motivations and subjective biases given the complexity of human behavior. b) Scientists have to reduce complex phenomena to simple, testable hypotheses. c) Scientific researchers have ethical and legal responsibilities that can constrain their work. d) Scientific research cannot answer value-based problems. e) All of the above are limitations on scientific research.
12 Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World Short Answer 1. You are studying the effects of artificial sweetener on mice. Four groups of mice consume different amounts of sweetener in their food. How much sweetener would the control group receive? Explain your answer. 2. You are testing treatments for cancer patients and find that 75% of patients respond very well to a particular treatment while 25% show no improvement or decline in health after taking the experimental treatment. What should you do next? 3. It is notoriously difficult to perform unbiased studies when human subjects are used. When governmental agencies (like the FDA) are trying to determine the validity of scientific claims, they very closely examine the method in which the experimental studies were done. Name several things that would be important in evaluating how the studies were performed. 4. There are many nutritional supplements on the market that allege that they can cause weight loss without dieting or exercise. Suppose you read a claim that a particular supplement causes weight loss and you are given the following information: People were weighed at the beginning of the study. People were asked to take two pills per day. People were weighed at the end of the study. People who took the supplement for four weeks seemed to have lost some weight at the end of the study. It was concluded that the supplement is helpful for weight loss. This study has some obvious holes in it. Explain five things that could be done to this study to improve it. Do not assume any information other that what has been provided.
Chapter 1. Scientific Thinking: Your Best Pathway to Understanding the World 13 5. Explain the importance of placebos in human clinical trials. Are placebos a form of treatment? Explain your answer. 6. Suppose that data are collected that appear to link to variables. The data suggest that as hours of sleep per night decline, reaction times to various stimuli also decrease. Is this an example of a positive or negative correlation? Explain your answer. 7. Your roommate exhibits a particular ritual before each exam she takes because she is convinced that this ritual ensures her success on exams. She eats the same meal the night before, goes to bed at exactly the same time, listens to the same song the morning of the exam, and always wears the same sweatshirt to the exam. Design an experiment that will help to determine if her ritual does in fact enhance her exam performance. 8. It is not uncommon to see statistics manipulated in the media and in marketing in order to convince people that a certain treatment has a more pronounced effect than it really does. An example is a weight loss supplement advertised that has caused 514% more weight loss than a competing product. What information do you need to know in order to put this statistic in context?