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Chapter 1 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. 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
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Chapter 1 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.
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
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
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
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.
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.
Components of the Scientific Method • Observation • Questioning and exploration • Forming and testing hypotheses • Evaluation of new information • Review by peers
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.
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
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
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
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.
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.
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.
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
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.
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.
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.
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.
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.
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.
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.
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
What makes something alive? • Living things can manipulate energy and matter.
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.
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.
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.
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.
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.
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
