1. Invitation to Biology Chapter 1

2. Biology Scientific study of life Lays the foundation for asking basic questions about life and the natural world

3. What Am I Doing Here? To learn how organisms are constructed, how they function, where they live, and what they do To help develop, modify, and refine ideas about life

4.  Biology is a way of thinking critically about life  Biology can help us to better understand human impact on nature, such as an oil field burning out of control during the Persian Gulf War Impacts, Issues: What Am I Doing Here? Fig. 1.1, p.2

5. Life’s Underlying Unity Life’s organization extends from the molecular level to the biosphere Shared features at the molecular level are the basis of life’s unity

6. Life’s levels of organization Levels of Organization

7. Molecules of Life Atoms are the basic units of matter Living things are made up of a certain subset of molecules: –Nucleic acids –Proteins –Carbohydrates –Lipids

8. Nothing Lives without Energy Energy = capacity to do work Metabolism = processes by which cells acquire and use energy for maintenance, growth, and reproduction

9. Energy Flow Usually starts with energy from the sun Transfers from one organism to another Flows in one direction Eventually is lost as heat

10. Interdependencies among Organisms Producers Make their own food Consumers Obtain energy by eating other organisms Decomposers Break down remains and wastes

11. Energy input, from sun Nutrient Cycling Producers plants, and other self-feeding organisms Consumers animals, most fungi, many protists, many bacteria Energy output (mainly metabolic heat) Fig. 1-3, p.5

12. Unity of Life All organisms –Consist of one or more cells –Have the capacity to reproduce based on instructions in DNA –Engage in metabolism –Sense and respond to the environment

13. Homeostasis Organisms maintain certain conditions in their internal environment A defining feature of life

14. Life’s Diversity Millions of living species Millions more now extinct Each species has some unique traits

15. Classification Systems Organisms are grouped into three domains: Eubacteria (Bacteria) Archaebacteria (Archaea) Eukaryotes (Eukarya)

16. Life’s diversity

17. Single celled No nucleus Smaller, less complex Archaebacteria, eubacteria ProkaryotesEukaryotes Single- or multicelled Nucleus Larger, more complex Fungi, protistans, plants, animals

18. Bacteria The most common prokaryotes

19. Archaea Prokaryotes

20. Mutation: Source of Variation Mutation = change in structure of DNA Basis for variation in heritable traits May be harmful, neutral, or beneficial

21. Evolution Heritable change in a line of descent over time Changes in populations result in diversity

22. Scientific Method Observe phenomenon Develop hypotheses Make predictions Devise test of predictions Carry out test and analyze results

23. Role of Experiments Study a phenomenon under known conditions Tests the prediction of the hypothesis Can never prove a hypothesis 100% correct

24. Experimental Design Control group –A standard for comparison –Identical to experimental group except for variable being studied Experimental group –Includes one variable being studied

25. Scientific Theory An explanation of the causes of a wide range of related phenomena Is consistent with all collected data Used to make predictions Still can be disproved

26. Experiments with Synthetic Fat Question: Does Olestra®, a synthetic fat replacement made from sugar and oil, cause intestinal cramps?

27. p.10 Designing an Experiment: Olestra ®

28. Results 93 of 529 people get cramps later (17.6%) 89 of 563 people get cramps later (15.8%) Experiment Control Group Eats regular potato chips Experimental Group Eats Olestra potato chips Fig. 1-8, p.10 Hypothesis Olestra® causes intestinal cramps. Prediction People who eat potato chips made with Olestra will be more likely to get intestinal cramps than those who eat potato chips made without Olestra Conclusion Percentages are about equal. People who eat potato chips made with Olestra are just as likely to get intestinal cramps as those who eat potato chips made without Olestra. These results do not support the hypothesis. Stepped Art Designing an Experiment: Olestra ®

29. Limits of Science Scientific method –cannot provide answers to subjective questions –cannot provide moral, aesthetic, or philosophical standards –may conflict with supernatural beliefs

30. Limits of Science The external world, not internal conviction, is the testing ground for scientific theories

31. Table 1-1, p.13