1. Copyright © 2009 Pearson Education, Inc. © 2013 Pearson Education, Inc. PowerPoint Lecture prepared by Jill Feinstein Richland Community College Fourth Edition BIOLOGY Science for Life | with Physiology Colleen Belk Virginia Borden Maier Chapter 1 Can Science Cure the Common Cold? Introduction to the Scientific Method

2. © 2013 Pearson Education, Inc. 1 The Process of Science  Science refers to a body of knowledge  Science is not a giant collection of facts to be memorized.  It important to learn about the process of science called the scientific method.  The scientific method allows the solving of problems and answer questions.  Observations  Proposing ideas  Testing the ideas  Discarding or modifying ideas based on results

3. © 2013 Pearson Education, Inc. 1 The Process of Science The Nature of Hypotheses  Hypothesis: proposed explanation for a set of observations  Hypotheses needs to be:  Testable – it must be possible to examine the hypothesis through observations  Falsifiable – it must be able to potentially be proven false

4. © 2013 Pearson Education, Inc. 1 The Process of Science Where do hypotheses come from?  Both logical and creative influences are used to develop a hypothesis

5. © 2013 Pearson Education, Inc. 1 The Process of Science Scientific Theory  Powerful, broad explanation of a large set of observations  Based on well supported hypotheses  Supported by research from several different independent sources

6. © 2013 Pearson Education, Inc. 1 The Process of Science The Logic of Hypothesis Tests  Inductive reasoning: combining a series of specific observations into a generalization to create a hypothesis

7. © 2013 Pearson Education, Inc. 1 The Process of Science The Logic of Hypothesis Tests  To test the hypothesis use deductive reasoning:  This involves using a general principle to predict an expected observation using if/then statements  For example, If vitamin C decreases the risk of catching a cold, then people who take in additional Vitamin C will get less colds.

8. © 2013 Pearson Education, Inc. 1 The Process of Science The Logic of Hypothesis Tests  The process looks something like this:

9. © 2013 Pearson Education, Inc. 1 The Process of Science

10. © 2013 Pearson Education, Inc. 1 The Process of Science The Logic of Hypothesis Tests  A hypothesis that fails our test is rejected and considered disproven.  A hypothesis that passes is supported, but not proven.  Why not? An alternative hypothesis might be the real explanation.

11. © 2013 Pearson Education, Inc. 2 Hypothesis Testing  The most powerful way to test hypotheses: do experiments  Experiments support the hypothesis that the common cold is caused by a virus.

12. © 2013 Pearson Education, Inc. 2 Hypothesis Testing The Experimental Method  Experiments are designed to collect data or information to test specific hypotheses.  Variables: factors that can change in value under different conditions  Independent variables can be manipulated by the scientist  Dependent variables cannot be changed by the researcher

13. © 2013 Pearson Education, Inc. 2 Hypothesis Testing Controlled Experiments  Controlled experiment: tests the effect of a single variable  Control: a subject who is not exposed to the experimental treatment but has all other variables the same

14. © 2013 Pearson Education, Inc. 2 Hypothesis Testing Controlled Experiments  Differences seen between the experimental group and control group can be attributed to the experimental treatment.  Random Assignment  An effective way of assigning individuals to groups for testing

15. © 2013 Pearson Education, Inc. AnimationAnimation: Science as a Process: Arriving at Scientific Insights Click “Go to Animation” / Click “Play”

16. © 2013 Pearson Education, Inc. 2 Hypothesis Testing Controlled Experiments  Example: Echinacea tea experiment:  Hypothesis: drinking Echinacea tea relieves cold symptoms  Experimental group drinks Echinacea tea 5-6 times daily.  Control group drinks “sham” Echinacea tea 5-6 times daily (placebo).  Both groups rated the effectiveness of their treatment on relieving cold symptoms.

17. © 2013 Pearson Education, Inc. 2 Hypothesis Testing Controlled Experiments  People who received echinacea tea felt that it was 33% more effective at reducing symptoms.

18. © 2013 Pearson Education, Inc. 2 Hypothesis Testing Minimizing Bias in Experimental Design  If human subjects know whether they have received the real treatment or a placebo, they may be biased.  Blind experiment: subjects don’t know what kind of treatment they have received  Double blind experiment: the person administering the treatments and the subjects do not know who is in each gropu until after the experiment is over

19. © 2013 Pearson Education, Inc. 2 Hypothesis Testing Minimizing Bias in Experimental Design

20. © 2013 Pearson Education, Inc. 2 Hypothesis Testing Using Correlation to Test Hypotheses  The “gold standard” for experimentation  Double-blind, placebo controlled and randomized experiments  Model systems can be used in experiments when it appears to dangerous or unethical to test on humans  examples: mice, rats, dogs and pigs  A correlation can be used to test hypotheses when controlled experiments on humans is impossible to perform

21. © 2013 Pearson Education, Inc. 2 Hypothesis Testing Using Correlation to Test Hypotheses  Using existing data, is there a correlation between variables?  Hypothesis: stress makes people more susceptible to catching a cold  Is there a correlation between stress and the number of colds people have caught?

22. © 2013 Pearson Education, Inc. 2 Hypothesis Testing Using Correlation to Test Hypotheses  Results of such a study: the number of colds increases as stress levels increase.  Caution! Correlation does not imply causation.

23. © 2013 Pearson Education, Inc. 2 Hypothesis Testing Using Correlation to Test Hypotheses  The correlation might be due to other reasons.

24. © 2013 Pearson Education, Inc. 2 Hypothesis Testing

25. © 2013 Pearson Education, Inc. 3 Understanding Statistics Overview: What Statistical Tests Can Tell Us  Statistics in science is used to evaluate and compare data.  We can extend the results from small samples to an entire population using statistical tests.  Statistically significant: results of difference between groups is due to random chance and not an error in experimenting

26. © 2013 Pearson Education, Inc. 3 Understanding Statistics The Problem of Sampling Error  Sampling error: the effect of chance on experimental data  We can calculate the probability that a result is simply due to sampling error.  Confidence interval: the range of values from a sample that has a 95% probability of containing the true population mean (average)

27. © 2013 Pearson Education, Inc. 3 Understanding Statistics The Problem of Sampling Error

28. © 2013 Pearson Education, Inc. 3 Understanding Statistics Factors that Influence Statistical Significance  Sample size  The true difference between populations  Bigger is better: more likely to detect differences

29. © 2013 Pearson Education, Inc. 3 Understanding Statistics Factors that Influence Statistical Significance

30. © 2013 Pearson Education, Inc. 3 Understanding Statistics What Statistical Tests Cannot Tell Us  If an experiment was designed and carried out properly  If observer error occurred, only can evaluate the probability of sampling error  May not be of any biological significance

31. © 2013 Pearson Education, Inc. 4 Evaluating Scientific Information Primary Sources  Researchers can submit a paper about their results to a professional journal (primary source).  Primary Sources undergo peer review: evaluation of submitted papers by other experts  Secondary sources: books, news reports, the internet, and advertisements

32. © 2013 Pearson Education, Inc. 4 Evaluating Scientific Information Information from Anecdotes  Anecdotal evidence is based on one person’s experience, not on experimental data.  Example: a testimonial from a celebrity

33. © 2013 Pearson Education, Inc. 4 Evaluating Scientific Information Science in the News

34. © 2013 Pearson Education, Inc. 4 Evaluating Scientific Information Science in the News  Secondary sources may be missing critical information or report the information incorrectly.  Consider the source of media reports.  Be careful with the internet since anyone can post information.  Be very cautious about claims made in paid advertisements.

35. © 2013 Pearson Education, Inc. 4 Evaluating Scientific Information Understanding Science from Secondary Sources  Use your understanding of the process of science to evaluate science stories.  News media generally highlight only those science stories that seem newsworthy.  They are more likely to report a positive result than a negative one.

36. © 2013 Pearson Education, Inc. 5 Is There a Cure for the Common Cold?  No, but prevention methods are known.  Wash your hands!  No effect on cold susceptibility:  Vitamin C  Exposure to cold temperatures  Exercise  No vaccine for the common cold

37. © 2013 Pearson Education, Inc. A(n) ________ is a proposed explanation for a single observation.  scientific method  hypothesis  scientific theory  experiment

38. © 2013 Pearson Education, Inc. A(n) ________ is a proposed explanation for a single observation.  scientific method  hypothesis  scientific theory  experiment

39. © 2013 Pearson Education, Inc. Which of the following is a scientific hypothesis?  Jazz is better music than rap.  Garden fairies make tomatoes grow better.  Hunting species to extinction is wrong.  Increasing the amount of protein in a cow’s diet increases her milk yield.

40. © 2013 Pearson Education, Inc. Which of the following is a scientific hypothesis?  Jazz is better music than rap.  Garden fairies make tomatoes grow better.  Hunting species to extinction is wrong.  Increasing the amount of protein in a cow’s diet increases her milk yield.

41. © 2013 Pearson Education, Inc. Which of the following is correct?  A hypothesis can be wrong.  A hypothesis is not always testable.  A hypothesis can prove a person’s values.  A hypothesis should be formed before making any observations.

42. © 2013 Pearson Education, Inc. Which of the following is correct?  A hypothesis can be wrong.  A hypothesis is not always testable.  A hypothesis can prove a person’s values.  A hypothesis should be formed before making any observations.

43. © 2013 Pearson Education, Inc. Which of the following statements was developed using deductive reasoning?  People who take in large amounts of caffeine are irritable.  If subjects take in large amounts of caffeine, then it will increase irritability.  Large amounts of caffeine has shown to increase irritability.  Irritability has been shown to increase with a decrease in caffeine consumption.

44. © 2013 Pearson Education, Inc. Which of the following statements was developed using deductive reasoning?  People who take in large amounts of caffeine are irritable.  If subjects take in large amounts of caffeine, then it will increase irritability.  Large amounts of caffeine has shown to increase irritability.  Irritability has been shown to increase with a decrease in caffeine consumption.

45. © 2013 Pearson Education, Inc. In an experiment, Dr. Smith feeds different amounts of protein to dairy cows and measures the differences in their milk yields. What is the independent variable in Dr. Smith’s experiment?  time  milk yield  amount of protein  placebo

46. © 2013 Pearson Education, Inc. In an experiment, Dr. Smith feeds different amounts of protein to dairy cows and measures the differences in their milk yields. What is the independent variable in Dr. Smith’s experiment?  time  milk yield  amount of protein  placebo

47. © 2013 Pearson Education, Inc. What is happening in step #2 in the diagram?  The virus is introducing its genetic material into the cell.  The host cell is killed.  Copies of the virus are being made by the host cell.  The virus is being destroyed by the host cell.

48. © 2013 Pearson Education, Inc. What is happening in step #2 in the diagram?  The virus is introducing its genetic material into the cell.  The host cell is killed.  Copies of the virus are being made by the host cell.  The virus is being destroyed by the host cell.

49. © 2013 Pearson Education, Inc. What does this graph show?  There is no difference between placebo and zinc lozenges.  Taking placebo lozenges causes people to have more types of cold symptoms.  Zinc lozenges lead to people catching fewer colds.  People taking zinc lozenges show cold symptoms for a shorter period of time.

50. © 2013 Pearson Education, Inc. What does this graph show?  There is no difference between placebo and zinc lozenges.  Taking placebo lozenges causes people to have more types of cold symptoms.  Zinc lozenges lead to people catching fewer colds.  People taking zinc lozenges show cold symptoms for a shorter period of time.

51. © 2013 Pearson Education, Inc. The confidence interval is the range of values that has a _____ probability of containing the true population mean.  5%  30%  75%  95%

52. © 2013 Pearson Education, Inc. The confidence interval is the range of values that has a _____ probability of containing the true population mean.  5%  30%  75%  95%

53. © 2013 Pearson Education, Inc. A statistical test evaluates the chance of _______.  observer error.  sampling error.  alternative mechanisms.  need for controls.

54. © 2013 Pearson Education, Inc. A statistical test evaluates the chance of _______.  observer error.  sampling error.  alternative mechanisms.  need for controls.

55. © 2013 Pearson Education, Inc. Which of these statements about primary and secondary sources are correct?  Primary sources are written by researchers; secondary sources are written by book authors, news reporters, and advertisers.  Primary sources aren’t biased; secondary sources are biased.  Primary sources are not peer reviewed; secondary sources are peer reviewed.  Primary sources are less reliable; secondary sources are more reliable.

56. © 2013 Pearson Education, Inc. Which of these statements about primary and secondary sources are correct?  Primary sources are written by researchers; secondary sources are written by book authors, news reporters, and advertisers.  Primary sources aren’t biased; secondary sources are biased.  Primary sources are not peer reviewed; secondary sources are peer reviewed.  Primary sources are less reliable; secondary sources are more reliable.

57. © 2013 Pearson Education, Inc. What is the best way to prevent the common cold?  Take vitamin C.  Wash your hands.  Take zinc lozenges.  Get a cold vaccine.

58. © 2013 Pearson Education, Inc. What is the best way to prevent the common cold?  Take vitamin C.  Wash your hands.  Take zinc lozenges.  Get a cold vaccine.