Download Testing and Applying Your Understanding

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 biological literacy
• Apply the scientific method to everyday situations
• Understand the flexibility of the scientific method
• Be able to design critical experiments to test hypotheses
• 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
• Be able to 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. Science is a Collection of Facts and a Process for Understanding the World
• Define science:
• Define biology:
• The development of biological literacy is important for understanding social, political, medical, and legal issues. This
involves the ability to:
1.
2.
3.
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• Describe empirical knowledge.
• Explain how scientific thinking is different from other ways of thinking.
• Provide three examples of non-scientific ways of thinking.
1.
2.
3.
II. A Beginner’s Guide: What are the Steps of the Scientific Method?
• 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.
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• 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.
• 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
• Variables in an experiment are items that are subject to change. We often speak of the ability to control variables
during experimentation. A ________________________ in an experiment is a condition (or variable) that is applied to
certain individuals.
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• Explain how experimental and control groups differ from each other.
• Why is it so important to control variables in an experiment?
• In certain experimental designs, a placebo is used to help control variables. What is a placebo and how does it work?
• The use of placebos can lead to the placebo effect. Explain what this means.
B. Blinding
• 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?
IV. The Scientific Method Can Help Us to 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.
A. Statistics
• How can statistics put data in context to determine if a hypothesis is supported or not?
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• 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.
B. 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
C. 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:
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V. On the Road to Biological Literacy: What Are the Major Themes in Biology?
• 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
0 Evolution
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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 1 950s, 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 super- cooling 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.
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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.
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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.
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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?