Chapter 1: The Science of Biology

1. Chapter 1: The Science of Biology Key Concept: What is the goal of science? Standards: I&E: 1a-1g

2. 1-1: What Is Science? 1-1

3. The goal of science is to: • investigate and understand the natural world. • explain events in the natural world. • use those explanations to make useful predictions. 1-1

4. 1-2 How Scientists Work

5. Scientists follow logical steps to: (1) generate new ideas, (2) answer questions, and (3) draw conclusions. These steps are called the Scientific Method. 1-2

6. Scientific Method steps: 1. Observe, ask questions. 2. Formulate a hypothesis. 3. Design a controlled experiment. 4. Make careful observations. 5. Analyze and draw conclusions. 1-2

7. Thinking Like a Scientist • Scientific thinking begins with observation. • Observation is the process of gathering information about events or processes in a careful, orderly way. This leads to curiosity about something. 1-2

8. Curiosity HYPOTHESIS A possible explanation for an event or set of observations. - It is a prediction about the outcome of an experiment. 1-2

9. An "educated guess" 1-2

10. A hypothesis may be ruled out or confirmed. • A hypothesis must be testable. • They are tested by performing a controlled experiment. 1-2

11. Examples of hypotheses: • Seeds need light to grow. • Hyenas are closely related to dogs. (hyenas are more closely related to cats)

14. Hypotheses are often stated in “if - then” statements. • If hyenas are related to dogs, then genetic testing should show this. • If my dog likes brand “A” of dog food, then he will eat more of it. 1-2

15. What is a controlled experiment? • Two identical experiments: • Variables: factors which change or can affect things. • Control: setup where no change is made. 1-2

16. Redi’s Experiment 1 2 Experiments must be repeatable! 1-2

17. EXPERIMENT Next step is to record and analyze results: Data 1-2

18. Next step: Forming a Conclusion • Scientists use the data from an experiment to evaluate a hypothesis and draw a valid conclusion. • Redi’s results supported the hypothesis that maggots were produced by flies, not spontaneous generation.

19. The conclusion may, or may not support the hypothesis. If not, hypothesis can be changed. 1-2

20. All experiments have variables.Variable= factor that can change in an experiment. 1-2

21. Examples of variables: • Temperature • Length of time • Type of dog food Most scientific experiments are designed to consider only 1 variable.

22. Other variables must be controlled. The control variable stays the same, while the manipulated variable changes. 1-2

23. Example: We want to determine what makes the best bread.

24. Possible Manipulated Variables:(you would pick 1) • Amount of sugar • Presence of salt • Oven temperature • Baking time

25. What can be controlled: • Amount of water • Amount of yeast • Oven temperature • Baking time

26. With sugar No sugar (1 variable only!) Another example

27. A hypothesis that is supported by many experiments done over a period of time is called a Theory. Theories are not facts, but probable explanations. 1-2

28. Examples of theories • Theory of evolution • Theory of plate tectonics • The cell theory Theories are changeable and expandable, and most importantly, theories are FALSIFIABLE. 1-2

30. Observation Curiosity Experiment Hypothesis Experiment Experiment Theory Experiment (If all exp’ts support hypothesis) 1-2

31. 1–2 • In an experiment, the variable that is deliberately changed is called the • control. • manipulated variable. • responding variable. • constant control

32. 1–2 • The mistaken belief that living organisms can arise from nonliving matter is called • biogenesis. • Pasteur's theory. • spontaneous generation. • Spallanzani’s hypothesis.

33. 1–2 • Which of the following was the manipulated variable in Redi’s experiment? • the kind of meat used • the temperature the jars were kept at • the gauze covering on some jars • the kind of fly that visited the jars

34. 1–2 • A well-tested explanation that unifies a broad range of observations is a • hypothesis. • variable. • control. • theory.

35. 1–2 • A scientific explanation does not become a theory until • a majority of scientists agree with it. • it has been supported by evidence from numerous investigations and observations. • it is first proposed as an explanation. • it is published in a textbook.

36. Scientific Law • A theory attempts to explain everything about something, including its cause. • A scientific law describes something that is always true. It does not explain why, only that it does. 2-1

37. Examples of Scientific Laws: • Law of gravity: any 2 objects attract each other. (doesn’t say anything about why) • In biology, Law of Dominance: a dominant trait will show itself when a dominant and recessive trait are mixed. 2-1

38. Let’s experiment! Pill bug, sow bug, roly polies Phylum Crustacea – related to crabs, shrimp  We want to observe their behavior and see what environment they prefer. Manipulated variable = ? Control variables = ?

39. For example: Manipulated variable = moisture Hypothesis: If pill bugs prefer moist environments, then they will move to the side of a choice chamber which has more moisture.

40. Wink Dinkersen 8/20/09 Per. 3 • Title: Investigation of Roly Poly Behavior • Hypothesis: If roly polies prefer ______ environments, they will move toward the _____ side of a choice chamber. • Objective: To investigate . . . • Materials: • Choice chamber • 10 roly polies • paper circles • Stopwatch • Data table • Anything else • Procedure: • Make a choice chamber with 2 petri dishes • Line dishes with filter paper • Add 20 drops of water to one side • Count out 10 roly polies • Place 5 in each side of the choice chamber • Data table: • Graph on separate pg. • Conclusion:

41. Possible manipulated variables: (Each lab group picks one) • Moisture (dry vs. moist) • Light (light vs. dark) • Temperature • Color • Vinegar vs. water • Other?

42. Develop a hypothesis: • If pill bugs prefer _____________ then they will move to the ______________ side of the choice chamber. Dark Dark

43. Design an experiment: • State the objective of your experiment. Objective: to determine _____________________________.

44. Design an experiment: • List all the materials you will use. • Choice chamber • 10 roly polies • Paper towel • Timer • Data sheet • Whatever you need for your manipulated variable

45. Light vs. Dark:Aluminum foil to cover one side. Moist vs. Dry:Moist paper towel, dry paper towel. Warm vs. Cold:Ice pack for one side, book for other. Color:Colored paper for each side. Vinegar vs. Water:drops of vinegar for one side, drops of water for other.

46. Write your procedure in detail so that someone else could follow it: 1. Gather choice chamber (CC) and other materials to run expt. 2. cut out paper disk to fit in each side of CC. 3. Count out 10 roly polies. 4. Place 5 roly polies in each side of CC. 5. . . . 10. We will keep __?__, __?__, __?__, the same. Also tell me what the control variables are!

47. Lastly: • Make a data sheet • Assign roles (timer, recorder, etc.) • Do your experiment!

48. Table 1. The number of roly polies in each side over time.

49. Measurements: • Count how many bugs in each side every 60 seconds for 15 minutes. Do NOT harm or tease the creatures!

50. On paper (1 paper turned in per lab group): • Name, date, title of experiment • Hypothesis • Objective • List of materials • Outline of procedure • Data table • Area for graph of data • Conclusion