Concepts & Methods in Biology

1. Concepts & Methods in Biology Chapter 1

2. What is the goal of science? • Investigate and understand nature • Explain events in nature • Predict events from explanations

3. How is science studied? • Observations • Hypothesis • Experimentation • Data collection and analysis • Conclusions

4. Quantitative Observations based on numbers or quantities. Ex. 15 miles, 100 people Qualitative Observations that are descriptive. Ex. Cloudy sky, large teeth Observations Collection of data or evidence using the senses

5. Objective –without a predetermined view point (unbiased) Subjective – a predetermined view point, misleading (biased) Dangerous – Jewish people are inferior to Germans Objective Observations vs. Subjective Observations

6. Inductive Logic • Using observations and facts to arrive at generalizations or hypotheses • Observation: Eagles, swallows, and robins have feathers • Hypothesis: All birds have feathers

7. Deductive Logic • Drawing a specific conclusion based on a generalization • Generalization - Birds have feathers • Example - Eagles are birds • Conclusion - Eagles have feathers

8. CHILDBED FEVERA Nineteenth-Century Mystery

9. Background • When: 1844-1860. • Where: Vienna, Austria • Situation: Healthy women would deliver their babies and a few days later would be dead of childbed fever. Women who gave birth at home rarely died of childbed fever. Some women begged to give birth without medical attention in the street and be admitted to the hospital after the delivery.

10. Part 1 • What were Semmelweis’ initial observations? • What was the problem at hand? • What possible story might Semmelweis come up with to explain his problem? • How might Semmelweis test his suspicions?

11. Part 2 • Based on the information what possible story might Semmelweis come up with to explain the problem? • How could Semmelweis test his new hypothesis?

12. Part 3 • What conclusions can Semmelweis' make about his experiment? • How might Semmelweis revise his original hypothesis or his experiments to gain additional information?

13. Part 4 1. What, if any, role did serendipidity play in Semmelweis’ story of childbed fever?

14. What happened next? • Findings were met with hostility or dissmissed. • Was not able to retain his teaching post. • Returned to Hungary and was successful in ridding the St. Rochus hospital of the disease. • Published his findings once again and once again they were dismissed.

15. Semmelweis suffered a mental breakdown due to his constant rejection and eventually died of childbed fever, puerperal sepsis.

16. Scientific Method • How does the case of childbed fever illustrate the use of the scientific method? Go back through this case and indicate where the following parts of the following parts of the scientific method are found: observation, problem, hypothesis, experiment, conclusion

17. Hypothesis A possible answer to a scientific question or an explanation for a series of observations. What was Ignaz Semmelweis’s initial hypothesis after his friend died of child bed fever?

18. Role of Experiments • Procedures used to study a phenomenon under known conditions • Allows you to predict what will happen if a hypothesis is not wrong • Can never prove a hypothesis 100% correct

19. Experimental Design • Control group • A standard for comparison • Identical to experimental group except for variable being studied • Sampling error • Non-representative sample skews results • Minimize by using large samples

20. Data Recording and Analysis Clear, precise and objective. What was the data and analysis from Semmelweis’s experiment?

21. Conclusion • Evidence supports or refutes the hypothesis.

22. How Scientist Work Examples:

23. Spontaneous Generation Examples: Maggots come from meat Mice from wheat Beetles from cow dung Belief that living things arose from non-living things

24. Their Explantation Gods, witchcraft, mythology, devil

25. Francesco Redi and Spontaneous Generation Section 1-2 OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat. HYPOTHESIS: Flies produce maggots. PROCEDURE Uncovered jars Covered jars Controlled Variables: jars, type of meat, location, temperature, time Several days pass Manipulated Variables: gauze covering that keeps flies away from meat Responding Variable: whether maggots appear Maggots appear No maggots appear CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

26. What is Redi’s Conclusion? • Spontaneous generation does not occur.

27. Lazzaro Spallanzini – improves Needham’s experiment The Return of Spontaneous Generation Anton van Leeunwenhoek – uses a microscope to find tiny organisms swimming in pond water. “animulcules” John Needham (mid 1700’s) performs an experiment that refutes Redi

28. Figure 1-10 Spallanzani’s Experiment Section 1-2 What are the controlled variables? What are the manipulated variables? Gravy is boiled. Flask is open. Gravy is teeming with microorganisms. Flask is sealed. Gravy is free of microorganisms. Gravy is boiled.

29. The debate continues Louis Pasteur – 1864, his experiment finally disproved spontaneous generation Pasteurization In the 1800’s some believe the air contained a “life force” perpetuating the belief of spontaneous generation.

30. Figure 1-11 Pasteur’s Experiment Section 1-2 Broth is boiled. Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms.

31. Figure 1-11 Pasteur’s Experiment Broth is boiled. Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms.

32. Figure 1-11 Pasteur’s Experiment Broth is boiled. Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms.

33. Limits of Science • Scientific approach cannot provide answers to subjective questions • Cannot provide moral, aesthetic, or philosophical standards

34. Scientific Theory • A hypothesis that has been tested for its predictive power many times and has not yet been found incorrect • Has wide-ranging explanatory power • Darwin’s Theory of Evolution by Natural Selection

35. Science and the Supernatural • Science has run up against religious belief systems • Copernicus suggested that sun, not the Earth, was center of universe • Darwin suggested that life was shaped by evolution, not a single creation event

36. Asking Questions • Scientists still ask questions that challenge widely held beliefs • The external world, not internal conviction, is the testing ground for scientific beliefs

37. Why Study Biology? • To learn how organisms are constructed, how they function, where they live, and what they do • To help you develop, modify, and refine your ideas about life

38. Studying Life • What do all living things have in common? List 5 things that all living things do.

39. Is a hurricane alive?

40. Are flowers alive?

41. Is a fire Alive?

42. Is a dragon fly Alive?

43. Is a river alive?

44. Is a crowd alive?

45. The characteristics of living things

46. Living Things are Made of Cells Unicellular vs. multicellular

47. All living things reproduce.

48. Asexual Reproduction - the new organism has a single parent, clone

49. Sexual Reproduction - 2 cells from separate parents unite to produce the first cell of an organism

50. Universal Genetic Code DNA - deoxyribose nucleic acid