Chapter 1: The Science of Biology

1. Chapter 1: The Science of Biology Key Concept: What is the goal of science?

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. 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. 1-1

5. 1-2 How Scientists Work

6. 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

7. Scientific Method steps: • 1. Observe, ask questions. • 2. Formulate a hypothesis. • 3. Design a controlled experiment. • 4. Making careful observations. • 5. Analyzing and drawing conclusions. 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 proposed in a way that can be tested. • Hypotheses are tested by performing controlled experiments or by gathering new data. 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 lettuce seeds need red light to grow, then they will grow better when exposed to light. • Ifhyenas are related to dogs, then genetic testing should show this. 1-2

15. The scientific method uses a controlled experiment to test a hypothesis. • Two identical experiments: • Variables: factors which change or potentially affect things. • Control setup where no change made. 1-2

16. Redi’s Experiment 1-2

17. EXPERIMENT Hypothesis must be clearly stated at beginning of experiment. 2-1

18. EXPERIMENT And, the experiment must be repeatable. 2-1

19. When doing experiment, it is very important to distinguish between observations and conclusions! Consider observations thoughtfully before drawing conclusions. (Boiling water may not be 100 degrees C!) 1-2

20. Drawing 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.

21. The results of an experiment may, or may not support the hypothesis. If not, hypothesis can be changed. 1-2

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

23. Examples of variables: • Temperature • Length of time • Amount of sugar Most scientific experiments are designed to consider only 1 variable.

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

25. Example: We want to determine what makes the best bread. 2-1

26. Variables: • Amount of sugar • Presence of salt • Oven temperature • Baking time

27. What can be controlled: • Amount of water • Amount of yeast • Oven temperature • Baking time 2-1

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

29. 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. 2-1

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

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

32. 1–2 • In an experiment, the variable that is deliberately changed is called the • control. • manipulated variable. • responding variable. • constant control

33. 1–2 • The mistaken belief that living organisms can arise from nonliving matter is called • biogenesis. • Pasteur's theory. • spontaneous generation. • Spallanzani’s hypothesis.

34. 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

35. 1–2 • A well-tested explanation that unifies a broad range of observations is a • hypothesis. • variable. • control. • theory.

36. 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.

37. 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

38. 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

39. Let’s experiment! Pill bug, sow bug, roly polies Phylum Crustacea – related to crabs, shrimp Want to observe behavior and see what environment they prefer. 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 Per. 3 • Title: Investigation of Roly Poly Behavior • Hypothesis: If roly polies prefer moist environments, they will move toward the wet side of a choice chamber. • Objective: To investigate . . . • Materials: • 2 petri dishes • 2 pieces filter paper • Clear tape • 10 roly polies • 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 variables: (Pick one) • Moisture (dry vs. moist) • Light (light vs. dark) • Temperature • Color • Other?

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

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 variable

45. Design an experiment: • Outline your procedure in detail. • Make a data sheet • Assign roles (timer, recorder, etc.) • Do your experiment!

46. Write your procedure in detail: 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. . . .

47. Measurements: • Count how many bugs in each side every 30 seconds for 10 minutes. No bugs will be harmed in this expt!

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

49. Name: Per. 3 • Title: Investigation of Roly Poly Behavior • Hypothesis: If roly polies prefer moist environments, they will move toward the wet side of a choice chamber. • Objective: To investigate . . . • Materials: • Choice chamber • 10 roly polies • Stopwatch • Data table • Anything else you think you’ll need • 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:

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