1. Introduction to Biology2-

2. Why a Study of Biology is Important?
Societal
Medicine
Public Health
Worldwide Water Crisis 1-
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3. Why a Study of Biology is Important?
Philosophical
Evolution
Genetics 1-
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4. 1-
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5. 1-
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6. Why a Study of Biology is Important?
Personal
To be informed
Support your cause
Make it your life work 1-
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7. Biology is the science that studies life
[bahy-ol-uh-jee]
Bio = life
...ology = the study of
Biology is the science that studies life 1-
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8. The Scientific Method in Action
A systematic way of gaining information 1-
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9. The Scientific Method: Observation
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? 1-
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10. The Scientific Method: The Hypothesis
Hypothesizing
question an observation
propose possible solutions to questions based on what is already understood about the phenomenon
Hypotheses must:
be logical
account for all current information
make the least possible assumptions
be testable 1-
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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
Ways to test a hypothesis:
Gathering relevant historical information
Retrospective Studies
Make additional observations from the natural world
Experimentation 1-
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12. The Scientific Method: Experimentation
Experiments
rigorous tests to determine if the solutions are supported
Experiments attempt to recreation an occurrence
tests whether or not the hypothesis can be supported or rejected
There are many types of experiments
laboratory, clinical trials, surveys, statistical analyses 1-
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13. Experimental Design All experiments have key elements in common:
Experiments must be controlled
this means that all aspects except for one variable must be kept constant
usually include any two groups.
Experimental group: variable is altered, independent variable
Control group: variable is not altered, dependent variable
Experiments use models to recreate occurrences, but in a controlled setting
model organisms, ISS, cohorts 1-
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14. Experimental Design Experiments must:
use large numbers of subjects and/or must be repeated several times (replication)
be independently reproducible
The validity of experimental results must:
be tested statistically
chi-squared test for statistical significance
be scrutinized by other scientists
peer reviewed 1-
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15. Theory
If the hypothesis is supported by ample experimental data, it leads to a 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 1-
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16. 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. 1-
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17. Scientific Communication
Data is shared with the scientific community through research articles published in scientific journals.
peer review
Scientists present preliminary data at conferences.
Scientists collaborate directly by phone and . 1-
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18. A Sample Experiment Scientific American August 2010 1-
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19. A Sample Experiment
Article: Hardt, Marah J. and Safina, Carl. “Threatening Ocean Life from the Inside Out.” Scientific American August 2010: Vol
What types of observations were being made?
State a hypothesis that was tested.
Describe an experiment that was conducted.
Discuss a variable that was studied and describe how constants where maintained in the experiment.
How was a model system was used to simulate the conditions being studied.
How were the complex processes being studied reduced to their simplest parts?
What was learned from the experiments? 1-
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20. The Science of Biology
Chapter 1

21. 1.1 The Science of Life Biology unifies much of natural life
Biology attempts to define life
Biology Living reveals a hierarchical organization of living systems 2

22. Properties of Life Living organisms:
are composed of cells (Cellular Organization)
are complex and ordered (Ordered Complexity)
respond to their environment (Sensitivity)
can Grow, Develop and Reproduce
obtain and use energy (Energy Utilization)
maintain internal balance (Homeostasis)
allow for Evolutionary Adaptation
The definitions of life are adapting with the field
where do viruses fit in?

23. Levels of Organization
Cellular Level
Atoms molecules organelles cells
Organismal Level
Tissues organs organ systems
Population Level
Population species biological community
Ecosystem Level
Biological community + physical habitat (soil, water, atmosphere)
The Biosphere
The entire planet thought of as an ecosystem 4

24. Levels of Organization
Cellular Organization
cells
organelles
molecules
atoms
The cell is the
basic unit of life.

25. Fig 6

26. Levels of Organization
Organismal Level
organism
organ systems
organs
tissues

27. Fig 8

28. Levels of Organization
Population Level
ecosystem
community
species
population

29. Fig 10

30. Levels of Organization
Each level of organization builds on the level below it but often demonstrates new features
Emergent properties: new properties present at one level that are not seen in the previous level
New properties emerging may be greater than the sum of the the parts

31. 1.2 The Nature of Science
Science aims to understand the natural world through observation and reasoning
Science begins with observations, therefore, much of science is purely descriptive
Science uses both deductive and inductive reasoning

32. The Nature of Science
Deductive reasoning uses general principles to make specific predictions.
Inductive reasoning uses specific observations to develop general conclusions.

33. The Nature of Science
Scientists use a systematic approach to gain understanding of the natural world:
Observation
Hypothesis formation
Prediction
Experimentation
Conclusion

34. The Nature of Science
A hypothesis is a possible explanation for an observation.
A hypothesis:
must be tested to determine its validity
is often tested in many different ways
allows for predictions to be made

35. The Nature of Science The experiment: tests the hypothesis
must be carefully designed to test only one variable at a time
consists of a test experiment and a control experiment

36. The Nature of Science
If the hypothesis is valid, the scientist can predict the result of the experiment
Conducting the experiment to determine if it yields the predicted result is one way to test the validity of the experiment

37. Think Like a Scientist

38. The Nature of Science Scientists may use:
reductionism - to break a complex process down to its simpler parts
models – to simulate phenomena that are difficult to study directly

39. Test the early hypothesis of Spontaneous Generation
Fig. 1.4

40. The Nature of Science A scientific theory:
is a body of interconnected concepts
is supported by much experimental evidence and scientific reasoning
expresses ideas of which we are most certain

41. 1.3 An Example of Scientific Inquiry: Darwin and Evolution
Charles Darwin served as naturalist on mapping expedition around coastal South America.
Used many observations to develop his ideas
Proposed that evolution occurs by natural selection

42. Voyage of the Beagle

43. Charles Darwin Evolution: Modification of a species over generations
“descent with modification”
Natural Selection: Individuals with superior physical or behavioral characteristics are more likely to survive and reproduce than those without such characteristics

44. Darwin’s Evidence Similarity of related species
Darwin noticed variations in related species living in different locations

45. Unnatural Selection

46. Population growth vs. availability of resources
Darwin’s Evidence
Thomas Malthus:
Population growth vs. availability of resources
-population growth
is geometric
-increase in food
supply is arithmetic

47. Darwin’s Evidence Population growth vs. availability of resources
Darwin realized that not all members of a population survive and reproduce
Deduced that the organisms best adapted to obtaining resources would survive to reproduce
Darwin based these ideas on the writings of Thomas Malthus

48. Post-Darwin Evolution Evidence
Fossil record
Intermediate Organisms
Mechanisms of heredity
- Early criticism of Darwin’s ideas were resolved by Mendel’s theories for genetic inheritance

49. Post-Darwin Evolution Evidence
Comparative anatomy
- Homologous structures have same evolutionary origin, but different structure and function.
- Analogous structures have similar structure and function, but different evolutionary origin.

50. Homologous Structures

51. Post-Darwin Evolution Evidence
Molecular Evidence
- Our increased understanding of DNA and protein structures has led to the development of more accurate phylogenetic trees.

52. 1.4 Unifying Themes in Biology
Cell theory
The cell theory describes the organization of living systems
All living organisms are made of cells, and all living cells come from preexisting cells

53. Single Celled Organisms34
Fig. 1.11a

54. Multi-Cellular Organisms35
Fig. 1.11b

55. 1.4 Unifying Themes in Biology
Molecular basis of inheritance
The molecular basis of inheritance explains the continuity of life
DNA encodes genes which control living organisms and are passed from one generation to the next
The DNA code is similar for all organisms (The Central Dogma)

56. Fig. 1.12 37

57. Unifying Themes in Biology
Structure and Function
The proper function of a molecule is dependent on its structure
The structure of a molecule can often tell us about its function
Four major classes of Biomolecules
Nucleic Acids
Amino Acids
Lipids
Carbohydrates

58. Unifying Themes in Biology
Evolutionary Change
The diversity of life arises by evolutionary change leading to the present biodiversity we see
Biology attempts to classify life’s great diversity based on these unifying themes
Currently all living things are classified into 3 Domains subdivided into Kingdoms (more on taxonomy to come)
This process is always changing

59. The Diversity of Life Three Domains: 1. Eukarya 2. Archaea 3. Bacteria40
Fig. 1.13

60. Domain Eukarya is Divided into four Kingdoms: 1. Plantae 2. Fungi
3. Animalia
4. Protista 41
Fig

61. Fig 42

62. Fig 43

63. Unifying Themes in Biology
Evolutionary Conservation
Evolutionary conservation explains the unity of living systems
The underlying unity of biochemistry and genetics argues that all life has evolved from the same origin event
Critical characteristics of early organisms are conserved and passed on to future generations

64. Homeodomains 45
Fig. 1.14

65. Unifying Themes in Biology
Cells are information-processing systems
Every cell in an organism carries the same genetic information
The control of gene expression allows cells to differentiate into different cell and tissue types
Cells also process information received from the environment and respond to maintain homeostasis

66. Unifying Themes in Biology
Emergent properties
New properties are present at one level of organization that are not seen in the previous level
The whole is greater than the sum of its parts

67. The Science of Biology
End Chapter 1