1-1 What is Science?

2. 1-1 What is Science? • OBJECTIVES: • Explain what the goal of science is • Explain what a hypothesis is

4. What Science Is and Is Not • The goal of science is to investigate and understand the natural world, to explain events in the natural world, and to use those explanations to make useful predictions • Science: • Deals only with the natural world • Collects and organizes information carefully • Proposes explanations that can be tested by examining evidence

6. Thinking Like a Scientist • Scientists begin by making observations about events or processes • The information gathered through observations is called data • Data can be quantitative (numbers) or qualitative (descriptions) • Scientists use data to make inferences - logical interpretations based on prior knowledge or experience

8. Explaining & Interpreting Evidence • Hypothesis: A scientific explanation for a set of observations • Hypotheses must be able to be tested with controlled experiments or by gathering more data

9. Science as a Way of Knowing • Science is not unchanging knowledge – it is an ongoing process • Scientific understanding is always changing due to new tools, techniques, and discoveries • The focus of biologists is on living systems that range in size from the invisibly small to the size of the entire planet

11. Science & Human Values • An understanding of science and the scientific approach is is essential in order to make decisions about many current issues • Smoking & lung disease • Cancer • AIDS • Heart Disease • Environmental concerns

12. 1-1 Section Assessment • What does science study? • What does it mean to describe a scientist as skeptical? Why is skepticism considered a valuable quality in a scientist? • What is the main difference between qualitative and quantitative observations?

13. 1-1 Section Assessment 4. What is a scientific hypothesis? In what two ways can a hypothesis be tested? 5. Is a scientific hypothesis accepted if there is no way to demonstrate that the hypothesis is wrong? Explain your answer. 6. Suppose a community proposes a law to require the wearing of seatbelts in all moving vehicles. How could scientific research have an impact on the decision?

14. 1-2: How Scientists Work • OBJECTIVES: • Describe how scientists test hypotheses • Explain how a scientific theory develops

15. Designing an Experiment • Asking Questions • Forming a hypothesis • Setting up a controlled experiment • Use only one variable • Control (keep unchanged) all others • Manipulated variable is changed • Responding variable is observed • Recording & analyzing results • Drawing conclusions

16. * Francesco Redi (1668) • Tested the hypothesis of spontaneous generation (life could arise from nonliving matter) • Uncovered jars with meat (variable) • Covered jars with meat (control) • Maggots only formed in the uncovered jars – spontaneous generation did not occur

19. Publishing & Repeating Investigations • Publishing data is important so other can repeat the same experiments • Needham (1700’s) – used gravy and showed that microorganisms could arise spontaneously under the right conditions • Spallanzani reviewed Needham’s work and saw that it was flawed - no spontaneous generation • Pasteur also showed that life can only come from other living things

21. When Experiments are not Possible • Field studies can be used for wild creatures • Testing on humans? • Try to identify and control as many variables as possible

22. How a Theory Develops • A theory develops when a hypothesis becomes well-supported (Ex: Theory of Biogenesis) • In science, a theory is a well-tested explanation that unifies a broad range of observations • Theories can be revised or replaced if new evidence is discovered

23. 1-2 Section Assessment • Why is Redi’s experiment on spontaneous generation considered a controlled experiment? • How does a scientific theory compare with a scientific hypothesis? • How do scientists today usually communicate their results and conclusions?

24. 1-2 Section Assessment • 4. How did the design of Pasteur’s flask help him successfully refute the hypothesis of spontaneous generation? • 5. Evaluate the impact of Pasteur’s research on both scientific thought and society. What was the effect of Pasteur’s investigations on scientists’ ideas and peoples lives?

25. 1-3: Studying Life • OBJECTIVES: • What are the characteristics of living things? • How can life be studied at different levels? • Biology - The study of life -or- the science that seeks to understand the living world

26. Characteristics of Living Things • Made of cells (enclosed collections of living matter) • Reproduction (sexual = 2 parents, asexual = 1) • Based on a genetic code (DNA) • Growth and development • Need for materials and energy (metabolism- chem. reactions that build or break down materials) • Response to the environment (stimulus) • Maintaining internal balance (Homeostasis- keeping internal conditions constant) • Evolution (groups of organisms change over time)

27. Characteristics of Life

28. Characteristics of Life

37. Branches of Biology • Molecules - Groups of atoms • Cells - Smallest functional unit of life • Groups of cells - tissues, organs, organ systems • Organism - Individual living thing • Population - Groups of organisms of one type • Community - All populations in an area • Ecosystem - Community & nonliving surroundings • Biosphere - Contains all ecosystems

48. Biology in Everyday Life • Appreciation of life • Food and health • Environmental threats • Quality of life

49. 1-3 Section Assessment • Describe five characteristics of living things • What topics might biologists study at the community level of organization? • Compare sexual reproduction and asexual reproduction. • What biological process includes chemical reactions that break down materials?

50. 1-3 Section Assessment 5. What is homeostasis? Give an example of how it is maintained? 6. Suppose you feel hungry, so you reach for a peach you see in a fruit bowl. Explain how both external and internal stimuli are involved in your action.