1. 1-1 Chapter 1 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.

2. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-2 Why a Study of Biology is Important To be an informed citizen An understanding of biology is important to address a number of social issues today. – DNA testing – Birth control – Global warming – AIDS

3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-3 So then, what is biology? Biology is the science that deals with life. What is science? – A process used to solve problems and understand natural events – Involves the scientific method

4. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-4 Basic Assumptions in Science Scientists approach their work with some basic assumptions: – Natural events have specific causes. – The causes for events in nature can be identified. – Natural events follow general rules and patterns. – A recurrent natural event has a common cause. – Different people can observe the same natural events. – Natural laws hold true regardless of time and place. Example: Lightning

5. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-5 Scientists Look for Cause and Effect Relationships Events that happen simultaneously are correlated, but – may or may not have a cause and effect relationship. – Example: Autumn and falling leaves Events have a cause and effect relationship – when one event happens as a direct result of a preceding event. – Example: Lightning causes thunder.

6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-6 The Scientific Method A way of gaining information about the world that involves – forming possible solutions to questions. – rigorous testing to determine if the solutions are supported. – continual checking and rechecking to make sure that previous conclusions are still supported. – modification of unsupported conclusions.

7. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-7 Components of the Scientific Method Observation Questioning and exploration Forming and testing hypotheses Evaluation of new information Review by peers

8. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-8 The Scientific Method in Action

9. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-9 Observation, Questioning and Exploration An observation is a thoughtful and careful recognition of an event or a fact. The careful observation of a phenomenon leads to a question. – How does this happen? – What causes it to occur? The question must be testable. Scientists then explore scientific publications to find any information that has been gathered about the question.

10. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-10 Constructing Hypotheses Once the question is asked, scientists propose answers. These answers are hypotheses. Hypotheses must: – be logical – account for all current information – be testable – make the least possible assumptions

11. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-11 Testing Hypotheses Hypotheses need to be tested to see if they are supported or disproved. – Disproved hypotheses are rejected. – Hypotheses can be supported but not proven. There are several ways to test a hypothesis: – Gathering relevant historical information – Make additional observations from the natural world. – Experimentation

12. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-12 Experimentation An experiment is a re-creation of an occurrence. – It tests whether or not the hypothesis can be supported or rejected. Experiments must be controlled. – This means that all aspects except for one variable must be kept constant. – They usually include any two groups. Experimental group: variable is altered Control group: variable is not altered

13. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-13 Experimental Design The variable that is altered is called the independent variable. – Experiments should have only one independent variable. The variables that change in response to the independent variable are called dependent variables. – Changes in the dependent variables are documented as data. Data from the experiment is analyzed and hypotheses are rejected and revised or supported.

14. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-14 A Sample Experiment Hypothesis: Male sex hormones produced by the testes stimulate male birds to sing. Experimental group: Male birds with testes removed at birth. Control group: Male birds subjected to a similar surgery that were allowed to develop normally with testes. Independent variable: presence or absence of testes. Dependent variable: presence of singing behavior. Data: Male songbirds without testes do not exhibit singing behavior. Conclusion: Hypothesis is supported.

15. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-15 Experimental Data Experiments must: – use large numbers of subjects or must be repeated several times (replication). – be independently reproducible. The validity of experimental results must: – be tested statistically. – be scrutinized by other scientists. If the hypothesis is supported by ample experimental data, it leads to a theory.

16. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-16 Theory A theory may be defined as a widely accepted, plausible general statement about a fundamental concept in science. – The germ theory states that infectious diseases are caused by microorganisms. Many diseases are not caused by microorganisms, so we must be careful not to generalize theories too broadly. – Theories continue to be tested. Exceptions identified Modifications made

17. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-17 A Scientific Law A scientific law is a uniform and constant fact of nature that describes what happens in nature. – An example: All living things come from pre-existing living things. Scientific laws promote the process of generalization. – Inductive reasoning – Since every bird that has been studied lays eggs, we can generalize that all birds lay eggs. Once a theory becomes established, it can be used to predict specific facts. – Deductive reasoning – We can predict that a newly discovered bird species will lay eggs.

18. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-18 Scientific Communication Data is shared with the scientific community through research articles published in scientific journals. – These articles are usually scrutinized by other scientists before they are published. Scientists present preliminary data at conferences. Scientists collaborate directly by phone and e-mail.

19. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-19 Fundamental Attitudes in Science Scientists must distinguish between opinions and scientific facts. – Scientists’ opinions may become facts if supported by data. A good scientist must – be skeptical. – not be biased. – be honest in analyzing and reporting data. The critical difference between science and non- science is that in science, one can test the principle. In non-science, one may not be able to.

20. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-20 Theoretical vs. Applied Science Initially, some scientific data seems to be purely informational and not very practical. Practical applications usually follow the discoveries of basic science. – The discovery of the structure of DNA has led to new drug treatments for many diseases. – The discovery of microorganisms has led to a dramatic decrease in infectious disease and food preservation.

21. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-21 Science vs. Nonscience Scientists continually challenge and test principles to determine cause-and-effect relationships. – Biology, Physics, Chemistry, Astronomy Nonscientists cannot test their hypotheses directly and often cannot establish cause- and-effect relationships. – History, Literature, Philosophy, Art, Sociology, etc.

22. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-22 Pseudoscience A deceptive practice that uses the language of science to convince people into thinking that a claim has scientific validity. – Marketing claims of nutritional supplements. – Marketing claims of organic foods.

23. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-23 Limitations of Science The scientific method can only be applied to questions that have a factual base. Questions of morality, values, social issues and attitudes cannot be tested scientifically. Science is limited by scientists. – People are fallible. – The sun orbits the earth. But, science is self-correcting. – New data shapes new hypotheses. – The earth rotates on its axis, so maybe the earth orbits the sun.

24. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-24 The Science of Biology Biology is the study of living things. Theoretical biology – Evolutionary biology, animal behavior, biochemistry Applied biology – Medicine, crop science, plant breeding, wildlife management

25. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-25 What makes something alive? Living things can manipulate energy and matter.

26. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-26 Characteristics of Living Things Metabolic processes – Organisms gain and store energy in the chemical bonds in the nutrients they take in. Generative processes – Organisms grow by increasing the number of cells. – Organisms reproduce either sexually or asexually.

27. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-27 Characteristics of Living Things Responsive processes – Organisms react to changes in their environment. Irritability: the ability to recognize that something in its surroundings has changed (a stimulus) and respond to it quickly. Individual adaptation: a longer term response to an environmental change. Evolution: changes in a population over time.

28. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-28 Characteristics of Living Things Control processes – Enable organisms to carry out metabolic processes in the right order. Coordination: Enzymes coordinate metabolic reactions. Regulation: Enzymes are regulated in order to maintain homeostasis. Unique structural organization – Organisms are made of cells.

29. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-29 Levels of Biological Organization Biosphere—the worldwide ecosystem. Ecosystem—communities that interact with one another in a particular place. Communities—populations of different organisms interacting with each other in a particular place. Population—a group of individual organisms in a particular place. Organism—an independent living unit.

30. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-30 Levels of Biological Organization Organ system—many organs that perform a particular function. Organ—many tissues that perform a particular function. Tissue—many cells that perform a particular function. Cell—simplest unit that shows characteristics of life. Molecules—specific arrangements of atoms. Atoms—the fundamental units of matter.

31. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-31 The Significance of Biology in our Lives Biology has significantly contributed to our high standard of living. For example: – Advanced food production – Significant progress in health – Advances in disease control – Advances in plant and animal breeding – Advances in biotechnology – Progress in genome studies

32. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-32 Biological Research Improves Food Production