1. Chapter 1 Lecture Outline See PowerPoint Image Slides
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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
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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
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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
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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.
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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.
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7. Components of the Scientific Method
Observation
Questioning and exploration
Forming and testing hypotheses
Evaluation of new information
Review by peers
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8. The Scientific Method in Action
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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.
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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
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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
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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
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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.
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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.
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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.
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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
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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.
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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 .
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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.
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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.
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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.
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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.
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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.
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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
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25. What makes something alive?
Living things can manipulate energy and matter.
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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.
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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.
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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.
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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.
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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.
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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
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32. Biological Research Improves Food Production
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