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. 1.1 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 answering of questions  done by:  making observations  proposing ideas in the form of hypotheses  testing these ideas through experimentation  discarding or modifying ideas based on results

3. © 2013 Pearson Education, Inc. 1.1 The Process of Science The Nature of Hypotheses  Hypothesis: proposed explanation for one or more observations  essentially a guess on “how things work”  Mom says – “wear a hat or you will get a cold”  her hypothesis is based on her theory that being chilled will increased your chances of getting a cold

4. © 2013 Pearson Education, Inc. 1.1 The Process of Science Where did Mom get this hypothesis from?  both logical and creative influences are used to develop a hypothesis

5. © 2013 Pearson Education, Inc. The Nature of Hypotheses  a hypothesis needs to be:  Testable – you have to be able to examine the hypothesis through observations  the observations must have a material nature and must be measureable  some hypotheses are not testable and are therefore not proper hypothesis  e.g. get a cold because of a disturbance in psychic energy

6. © 2013 Pearson Education, Inc. The Nature of Hypotheses  a hypothesis needs to be:  Falsifiable – the hypothesis must be able to potentially be proven false  in science incorrect ideas must be discarded  e.g. being chilled will give you a cold  we can imagine a situation where this is not true

7. © 2013 Pearson Education, Inc. 1.1 The Process of Science Ulcers and Bacteria  long held belief that foods can cause ulcers  e.g. spicy food upsets your stomach through increased acid production  ulcers  based on standard medical practice for ulcers  drugs that lower stomach acid levels  1982 – Australian scientists Robin Warren and Barry Marshall  found a specific strain of bacteria in tissue samples taken from ulcers  formulated a new hypothesis  Ulcers caused by this bacteria  series of well-controlled studies using the bacteria Helicobacter pylori  their hypothesis was testable and falsifiable  end result of their studies? Hypothesis was not rejected

8. © 2013 Pearson Education, Inc. 1.1 The Process of Science Ulcers and Bacteria  today this hypothesis is accepted by the scientific community  their work was rigorous and well-controlled and reviewed by many other scientists with knowledge in the field  ALSO – no well-controlled studies examining a link between spicy foods and ulcers have been published  so no alternative hypothesis has been proven

9. © 2013 Pearson Education, Inc. 1.1 The Process of Science Scientific Theory  Marshall and Berry based their hypothesis on previous scientific knowledge  called the germ theory of disease  the germ theory of disease is an example of a Scientific Theory  Powerful, broad explanation of a large set of observations  Based on well supported hypotheses  Supported by research from several different independent sources

10. © 2013 Pearson Education, Inc. 1.1 The Process of Science What is a Theory?  common meaning = untested hypothesis based on little information  in science = theory is a well-supported idea on how the natural world works  based on previous observations  Marshall and Berry based their theory that bacteria cause ulcers and their hypothesis that H. pylori causes human stomach ulcers on the germ theory started by Louis Pasteur

11. © 2013 Pearson Education, Inc. 1.1 The Process of Science The Logic of Hypothesis Tests  Inductive reasoning: combining a series of specific observations into a generalization to create a hypothesis  Hypothesis: You can prevent a cold by taking vitamin C  this hypothesis was created through inductive reasoning  based on some well-known facts:  1. fruits and veggies contain vitamin C  2. people with diets rich in fruits and veggies are healthier  3. vitamin C in an anti-inflammatory and can reduce nose and throat irritation

12. © 2013 Pearson Education, Inc. 1.1 The Process of Science The Logic of Hypothesis Tests  To test the hypothesis you use deductive reasoning:  involves using a general principle to predict an expected observation using if/then statements  essentially you make a prediction  e.g. - If vitamin C decreases the risk of catching a cold, then people who take in additional Vitamin C will get less colds.

13. © 2013 Pearson Education, Inc. 1.1 The Process of Science The Logic of Hypothesis Tests  The process looks something like this:

14. © 2013 Pearson Education, Inc. 1.1 The Process of Science  So – HOW WOULD YOU GO ABOUT TESTING YOUR PREDICTION????

15. © 2013 Pearson Education, Inc. 1.1 The Process of Science

16. © 2013 Pearson Education, Inc. 1.1 The Process of Science The Logic of Hypothesis Tests  A hypothesis that fails our test is rejected and considered disproven.  NOT ONE PUBLISHED STUDY ON VITAMIN C SHOWS IT CAN PREVENT COLDS!!!  A hypothesis that passes is supported  but not proven  Why not? An alternative hypothesis might be the real explanation.

17. © 2013 Pearson Education, Inc. 1.2 Hypothesis Testing  The most powerful way to test hypotheses: do experiments  Experiments support the hypothesis that the common cold is caused by a virus.

18. © 2013 Pearson Education, Inc. 1.2 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

19. © 2013 Pearson Education, Inc. 1.2 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

20. © 2013 Pearson Education, Inc. 1.2 Hypothesis Testing Controlled Experiments  HYPOTHESIS: Compound “X” can make cells grow faster  EXPERIMENT: take cells and expose them to Compound “X”  GROUP #1: cells grown in the lab for 14 days in a media containing Compound X  GROUP #2: same cells grown in the same lab for 14 days in the same media NOT containing Compound X  count the cells from the two groups and compare

21. © 2013 Pearson Education, Inc. 1.2 Hypothesis Testing Controlled Experiments  Differences seen between the experimental group and control group can be attributed to the experimental treatment. Compound X No Compound X

22. © 2013 Pearson Education, Inc. Animation: Science as a Process: Arriving at Scientific Insights Click “Go to Animation” / Click “Play”

23. © 2013 Pearson Education, Inc. 1.2 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 rate the effectiveness of their treatment on relieving cold symptoms.

24. © 2013 Pearson Education, Inc. 1.2 Hypothesis Testing Controlled Experiments  People who received echinacea tea felt that it was 33% more effective at reducing symptoms.  can you say that echinacea tea prevents colds?  NO!!!!!  Why?

25. © 2013 Pearson Education, Inc. 1.2 Hypothesis Testing Controlled Experiments  Problems with this study  1. People in the study  sample size  sample composition  2. Data collection  e.g. surveys and subjectivity  3. Bias

26. © 2013 Pearson Education, Inc. 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 group until after the experiment is over

27. © 2013 Pearson Education, Inc. 1.2 Hypothesis Testing Using Correlation to Test Hypotheses  The “gold standard” for experimentation  Double-blind, placebo controlled and randomized experiments in humans  A correlation can be used to test hypotheses when controlled experiments on humans is impossible to perform  Model systems can be used in experiments when it appears to dangerous or unethical to test on humans  examples: mice, rats, dogs and pigs

28. © 2013 Pearson Education, Inc. 1.2 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?

29. © 2013 Pearson Education, Inc. 1.2 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.

30. © 2013 Pearson Education, Inc. 1.2 Hypothesis Testing Using Correlation to Test Hypotheses  The correlation might be due to other reasons.

31. © 2013 Pearson Education, Inc. 1.2 Hypothesis Testing

32. © 2013 Pearson Education, Inc. 1.3 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

33. © 2013 Pearson Education, Inc. 1.3 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)

34. © 2013 Pearson Education, Inc. 1.3 Understanding Statistics Factors that Influence Statistical Significance  Sample size  The true difference between populations  Bigger is better: more likely to detect differences

35. © 2013 Pearson Education, Inc. 1.3 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

36. © 2013 Pearson Education, Inc. 1.4 Evaluating Scientific Information 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  Anecdotal evidence is based on one person’s experience, not on experimental data.  Example: a testimonial from a celebrity

37. © 2013 Pearson Education, Inc. 1.4 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. 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.

38. © 2013 Pearson Education, Inc. 1.5 Is There a Cure for the Common Cold?  No vaccine for the common cold  No cure  but prevention methods are known.  #1 preventive measure - Wash your hands!  the media gives us poor information  no proven effect on cold susceptibility:  increased Vitamin C intake  exposure to cold temperatures  exercise

39. © 2013 Pearson Education, Inc. A(n) ________ is a proposed explanation for a single observation.  scientific method  hypothesis  scientific theory  experiment

40. © 2013 Pearson Education, Inc. A(n) ________ is a proposed explanation for a single observation.  scientific method  hypothesis  scientific theory  experiment

41. © 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.

42. © 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.

43. © 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.

44. © 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.

45. © 2013 Pearson Education, Inc. A statistical test evaluates the chance of _______.  observer error.  sampling error.  alternative mechanisms.  need for controls.

46. © 2013 Pearson Education, Inc. A statistical test evaluates the chance of _______.  observer error.  sampling error.  alternative mechanisms.  need for controls.