1. Biology: Life on Earth Lecture for Chapter 1
Teresa Audesirk • Gerald Audesirk • Bruce E. Byers
Biology: Life on Earth
Eighth Edition
Lecture for Chapter 1
An Introduction to Life on Earth
Copyright © 2008 Pearson Prentice Hall, Inc.

2. Section 1.1 Outline 1.1 How Do Scientists Study Life?
Life Can Be Studied at Different Levels of Organization
Scientific Principles Underlie All Scientific Inquiry
The Scientific Method is the Basis for Scientific Inquiry
Communication Is Crucial to Science
Science is a Human Endeavor
Scientific Theories Have Been Thoroughly Tested

3. Figure 1-1 Levels of organization of matter
All life has a chemical basis, but the quality of life itself emerges on the cellular level. Interactions among the components of each level and the levels below it allow the development of the next-higher level of organization.

4. Levels of Organization
A community and its nonliving environment is an ecosystem
The entire surface of the Earth, including living and nonliving components is the biosphere

5. Scientific Principles
Biology is a scientific discipline
All scientific inquiry is based on a small set of assumptions or principles
Natural causality
Uniformity in space and time
Similar perception

6. Natural Causality Historical approaches to studying life
Belief that some events happen through supernatural forces (e.g. the actions of Greek gods)
Belief that all events can be traced to natural causes that we can comprehend (natural causality)
Corollary: Evidence gathered from nature has not been deliberately distorted to fool us

7. Natural Laws Apply Everywhere
Natural laws are uniform in space and time
This principle is key understanding biological events (e.g. evolution) that occurred before humans recorded them

8. Similar Perceptions
Assumption that all human beings perceive natural events in fundamentally the same way
Common perception allows us to accept observations of other humans as reliable

9. Similar Perceptions
Common perception is usually not found in appreciation of art, poetry, and music, nor between cultures or religious beliefs
Value systems are subjective
Science requires objectively gathered data

10. The Scientific Method
Scientific inquiry is a rigorous method for making observations
The Scientific Method for inquiry follows 4 steps…

11. The Scientific Method Observation of a phenomenon
Subsequent development of questions
Formulation of a hypothesis
A supposition that explains an observed phenomenon, leading to testable predictions

12. The Scientific Method Testing through experimentation
Additional controlled observations
Development of a conclusion
Evaluation of hypothesis in light of experimental data

13. Figure 1-4a The scientific method
(a) The general process

14. The Scientific Method
Scientific experimentation tests the assertion that a single variable causes a particular observation
The experiment must rule out the influence of other possible variables on the recorded observations

15. The Scientific Method Controls are incorporated into experiments
Controls keep untested variables constant
Scientific method is illustrated by Francesco Redi’s experiment

16. Figure E1-1 The experiments of Francesco Redi

17. Application to Everyday Problems
Assume you are late for an appointment and hurriedly try to start your car
Observation: The car won’t start

18. Figure 1-4b (part 1) The scientific method
(a) The general process. (b) An example from everyday life.

19. Application to Everyday Problems
Hypothesis: the battery is dead

20. Figure 1-4b (part 2) The scientific method
(a) The general process. (b) An example from everyday life.

21. Application to Everyday Problems
Experimental design: Replace your battery with another and restart the car

22. Figure 1-4b (part 3) The scientific method
(a) The general process. (b) An example from everyday life.

23. Application to Everyday Problems
Premature conclusion:
The problem was a dead battery because the car starts when replaced with a different one

24. Application to Everyday Problems
Recognition of inadequate controls
Did you attempt to start the car more than once?
Was the battery cable on my original battery loose?

25. Application to Everyday Problems
Establishing a control
Reinstall your old battery, check for tight cables, now try to start the car
If car still fails to start on old battery, the only variable in this investigation now is the effectiveness of the battery

26. Figure 1-4b (part 4) The scientific method
(a) The general process. (b) An example from everyday life.

27. Application to Everyday Problems
Making a better conclusion, based on controlled experiments
Your battery was probably dead

28. Figure 1-4b (part 5) The scientific method
(a) The general process. (b) An example from everyday life.

29. Figure 1-4b The scientific method
(a) The general process. (b) An example from everyday life.

30. Limitations of the Scientific Method
Can never be sure all untested variables are controlled
Conclusions based on the experimental data must remain tentative

31. Limitations of the Scientific Method
Results of experimentation must be communicated thoroughly and accurately to other scientists for repetition
Repetition by other scientists add verification that findings can be used as the basis for further studies

32. Science Is a Human Endeavor
Human personality traits are part of “real science”
Scientists, like other people may be driven by pride, ambition, or fear
Scientists sometimes make mistakes
Accidents, lucky guesses, intellectual powers, and controversies with others contribute strongly to scientific advances

33. Science Is a Human Endeavor
In the 1920s, bacteriologist Alexander Fleming grew bacteria in cultures
One of the bacterial cultures became contaminated with a mold
Fleming nearly destroyed the culture when he noticed the mold (Penicillium) inhibited bacterial growth in the culture

34. Figure 1-5 Penicillin kills bacteria
A fuzzy white colony of the mold Penicillium has inhibited the growth of colonies of the disease-causing bacteria Staphlococcus aureus, which have been smeared back and forth across this plate of jellylike growth medium. Both the mold and the bacteria are visible only when they grow at high densities, as in the colonies seen here.

35. Science is a Human Endeavor
Fleming hypothesized that the mold produced an antibacterial substance
Further tests using broth from pure Penicillium cultures lead to the discovery of the first antibiotic, penicillin

36. Science is a Human Endeavor
Fleming continued beyond a lucky “accident” with further scientific investigation to a great discovery
“Chance favors the prepared mind” (Louis Pasteur)

37. Scientific Theory
A scientific theory differs in definition from that of everyday usage
Many people use the word theory to mean hypothesis, and “educated guess”

38. Scientific Theory
A scientific theory is a general explanation for important natural phenomena
It is extensively and reproducibly tested
It is more like a principle or natural law (e.g. the atomic, gravitational, and cell theories)
If compelling evidence arises, a theory may be modified

39. Scientific Theory
New scientific evidence may prompt radical revision of existing theory
Example: the discovery of prions…

40. Scientific Theory
Before 1980, all known infectious diseases contained DNA or RNA
In 1982, Stanley Prusiner showed that the infectious sheep disease scrapie is caused by a protein (a “protein infectious particle” or prion)

41. Scientific Theory
Prions have since been shown to cause “mad cow disease” and diseases in humans
The willingness of scientists to revise accepted belief in light of new data was critical to understanding and expanding the study of prions

42. Science Is Based on Reasoning
Inductive Reasoning
Used in the development of scientific theories
A generalization is created from many observations
e.g., the cell theory (all living things are made of one or more cells) arises from many observations that all indicate a cellular basis for life

43. Science Is Based on Reasoning
Deductive Reasoning
Generating hypotheses based on a well-supported generalization (such as a theory)
e.g., based on the cell theory, any newly discovered organism would be expected to be composed of cells

44. Section 1.2 Outline 1.2 Evolution: The Unifying Theory of Biology
Three natural processes underlie evolution
Much of organism variability is inherited
Natural selection preserves survival and reproductive genes

45. Unifying Theory of Biology
Abundant evidence has been found to support evolutionary theory since Darwin and Wallace proposed it in the mid-1800s
Those who see evolution as “just a theory” don’t understand the scientific definition of a theory

46. Unifying Theory of Biology
Evolution explains how diverse forms of life originated through changes in their genetic makeup
Modern organisms descended with modification from pre-existing life forms
“Nothing in biology makes sense, except in the light of evolution” (Theodosius Dobzhansky)

47. Three Natural Processes Underlie Evolution
Charles Darwin and Alfred Russel Wallace formulated the basis of our modern understanding of evolution
Evolution arises as a consequence of three natural processes…

48. Three Natural Processes Underlie Evolution
Genetic variation among members of a population
Inheritance of those variations by offspring of parents carrying the variation
Natural selection of individuals whose survival and enhanced reproduction are due to the favorable variations they carry

49. Genetic Variability
Genetic variation arises from segments of DNA (genes)
Changes in genes (mutation) alter the informational content
Mutations arise from a number of sources
Mutations can occur from irradiation
Mutations occasionally arise from copying mistakes in DNA during cellular reproduction

50. Genetic Variability Effects of mutation
No effect (harmless)
A decrease in organism’s ability to function
Death of the organism
An increase in an organism’s ability to survive and reproduce (rare)
Mutations occurring over millions of years and passed through many generations cause members of a species to be slightly different

51. Natural Selection
Organisms that best meet environmental challenges leave the most offspring
Natural selection preserves genes that help organisms flourish

52. Natural Selection
Adaptations are structures, physiological process, or behaviors that aid in survival and reproduction
Adaptations that are good for one environment may be poor in another
Species that cannot adapt to environmental change go extinct (e.g. the dinosaurs, illustrated by the Triceratops

53. Natural Selection
The many different habitats (environments) in an area coupled with evolutionary adaptive processes produce species variety or biodiversity
Humans are responsible for accelerating the rate of environmental change (and therefore the rate of extinction of species)

54. Figure E1-4 Biodiversity threatened
Destruction of tropical rain forests by indiscriminate logging threatens Earth's greatest storehouse of biological diversity. Interrelationships such as those that have evolved between this Heliconia flower and its hummingbird pollinator, and this frog and the bromeliad on which it lives, sustain these diverse communities and are threatened by human activities.

55. Section 1.3 Outline 1.3 What Are the Characteristics of Living Things?
Living Things Are Both Complex, Organized, and Composed of Cells
Living Things Respond to Stimuli
Living Things Maintain Relatively Constant Internal Conditions Through Homeostasis

56. Section 1.3 Outline
1.3 What Are the Characteristics of Living Things? (continued)
Living Things Acquire and Use Materials and Energy
Living Things Grow
Living Things Reproduce Themselves
Living Things as a Whole Have the Capacity to Evolve

57. Defining Life Dictionary definition of life is:
“the quality that distinguishes a vital and functioning being from a dead body”
Living things are more than the sum of their parts; life is difficult to define

58. Living Things Are Composed of Cells
The complexity and ordered interactions of parts in living things gives rise to certain emergent properties
Living things are complex and organized

59. Each crystal of table salt, sodium chloride, is a cube, showing great organization but minimal complexity.
Organized

60. The water and dissolved materials in the ocean represent complexity but very little organization.

61. Living things have both complexity and organization
Living things have both complexity and organization. The waterflea, Daphnia pulex, is only 1 millimeter long (1/1000 meter; smaller than the letter “i”), yet it has legs, a mouth, a digestive tract, reproductive organs, light-sensing eyes, and even a rather impressive brain in relation to its size.
Organized and complex

62. Living Things Are Composed of Cells
The cell theory states that the cell is the basic unit of life
A single cell has an elaborate internal structure

63. Figure 1-2 The cell is the smallest unit of life
This artificially colored micrograph of a plant cell shows the supporting cell wall that surrounds plant (but not animal) cells. Just inside the cell wall, the plasma membrane (found in all cells) has control over which substances enter and leave. The nucleus houses the cell's DNA. The cell also contains several types of specialized organelles. Some store food; some break down food to provide usable energy; and, in plants, some capture light energy.

64. Living Things Are Composed of Cells
All cells contain:
Genes that provide information to direct the cell
Organelles, small specialized structures that perform specific functions
A plasma membrane that encloses the fluid cytoplasm and organelles from the outside world

65. Homeostasis
Organisms must maintain relatively constant internal conditions (homeostasis)
e.g. many organisms regulate body temperature
Homeostatic mechanisms include
Sweating in hot weather or dousing oneself with cool water
Metabolizing more food, basking in the sun, or turning up the thermostat in cold weather
Organisms still grow and change while maintaining homeostasis

66. Figure 1-9 Living things maintain homeostasis
Evaporative cooling by water, both from sweat and from a bottle, helps Lance Armstrong (seven-time winner of the Tour de France bicycle race) maintain temperature homeostasis.

67. Living Things Respond to Stimuli
Organisms sense and respond to internal and external environmental stimuli
Sensory organs in animals can detect and respond to external stimuli like light, sound, chemicals, etc.
Internal stimuli in animals are perceived by stretch, temperature, pain, and chemical receptors
Plants and bacteria respond to stimuli as well (e.g. plants to light, bacteria to available nutrients in the medium)

68. Living Things Acquire Materials
Materials and energy required to maintain organization, to grow, and to reproduce
Important materials (nutrients) acquired from air, water, soil, or other living things
Nutrients are continuously recycled among living and nonliving things

69. Figure 1-8 Life is both complex and organized
The water flea, Daphnia longispina, is only 1 millimeter long (1/1000 meter), yet it has legs, a mouth, a digestive tract, reproductive organs, light-sensing eyes, and even a rather impressive brain in relation to its size.

70. Figure 1-10 The flow of energy and the recycling of nutrients
Nutrients are recycled among organisms and their nonliving environment. In contrast, energy is acquired from sunlight, transferred through heterotrophs (yellow arrows), and lost as heat (red arrows) in a one-way flow. Photosynthetic organisms (autotrophs) capture solar energy and obtain nutrients from soil and water. Other forms of life (heterotrophs) obtain their energy and most of their nutrients from autotrophs either directly (in the case of herbivores) or indirectly by consuming other heterotrophs (in the case of carnivores).

71. Living Things Acquire Materials
Nutrients are incorporated into the bodies of organisms
Metabolism is the sum total of all the chemical reactions needed to sustain an organism’s life

72. Living Things Acquire Materials
Organisms obtain energy in two ways
Plants and some single-celled organisms capture sunlight in photosynthesis.
Other organisms consume energy-rich molecules in the bodies of other organisms
All energy that sustains life comes directly or indirectly from the sun

73. Living Things Grow Every organism becomes larger over time
Plants, bird, and mammals grow by producing more cells to increase their mass
Bacteria grow by enlarging their cells; they also divide to make more individuals
Growth involves the conversion of acquired materials to molecules of the organism’s body

74. Living Things Reproduce Themselves
Organisms give rise to offspring of the same type (reproduction)
The parent’s genetic material (DNA) is passed on to the offspring, creating continuity of life
Diversity of life occurs because offspring may be genetically different from their parents
Figure: 19-2 part a
Title:
Viral structure and replication part a
Caption:
(a) A cross section of the virus that causes AIDS. Inside, genetic material is surrounded by a protein coat and molecules of reverse transcriptase, an enzyme that catalyzes the transcription of DNA from the viral RNA template after the virus enters the host cell. This virus is among those that also have an outer envelope that is formed from the host cell's plasma membrane. Spikes made of glycoprotein (protein and carbohydrate) project from the envelope and help the virus attach to its host cell.

75. Capacity to Evolve
The genetic composition of a whole species changes over many generations
Mutations and variable offspring allow a species to evolve

76. Capacity to Evolve
Evolutionary theory states that modern organisms descended with modification from pre-existing life-forms
Natural selection is a process where organisms with certain adaptations survive and reproduce more successfully than others

77. Section 1.4 Outline
1.4 How Do Scientists Categorize the Diversity of Life?
Prokaryotic and Eukaryotic Cell Types in the Domains
Unicellularity and multicellularity in Bacteria, Archaea, and the kingdoms of Eukarya
Ways Organisms Acquire Energy

78. Categorizing Life Organisms can be grouped into three domains
Bacteria (single, simple cells)
Archaea (single, simple cells)
Eukarya (one or more highly complex cells)

79. Figure 1-11 The domains and kingdoms of life

80. Categorizing Life
Domain Eukarya contains four subdivisions or kingdoms
Fungi
Plantae
Animalia
The “Protists”

81. Categorizing Life
There are exceptions to any simple set of rules used to distinguish the domains and kingdoms, but three characteristics are particularly useful
Cell type
The number of cells in each organism
Energy acquisition

82. Table 1-1 Some Characteristics Used in Classification of Organisms

83. Prokaryotic and Eukaryotic Cells
Cell types named after presence or absence of a nucleus
It’s all Greek!
Karyotic = nucleus
Prokaryotic = “before” nucleus
Eukaryotic = “true” nucleus

84. Prokaryotic and Eukaryotic Cells
Two cell types seen among all living things
Prokaryotic (“before nucleus” in Greek)
Only 1-2 micrometers in diameter
Lacking organelles or a nucleus
Cell type found in Domains Bacteria and Archaea

85. Prokaryotic and Eukaryotic Cells
Eukaryotic (“true nucleus” in Greek)
Larger than prokaryotic cells
Contain a variety of organelles, including a nucleus
Cell type found only among members of Domain Eukarya

86. Unicellularity vs. Multicellularity
Unicellular (single-celled) organisms found in:
Bacteria
Archaea
The protists in Eukarya

87. Unicellularity vs. Multicellularity
Multicellular (many-celled) organisms found in Eukarya
Kingdom Fungi
Kingdom Plantae
Kingdom Animalia

88. Ways Organisms Acquire Energy
Autotrophs (“self-feeders”)
Photosynthetic organisms that capture sunlight and store it in sugar and fats
Includes plants, some bacteria, and some protists

89. Ways Organisms Acquire Energy
Heterotrophs (“other-feeders”)
Organisms that acquire energy through ingesting molecules in the bodies of other organisms
Includes many archaeans, bacteria, protists, fungi, and animals
Size of food eaten varies from individual food molecules to ingestion and digestion of whole chunks

90. Figure 1-13 Wild lupines and subalpine fir trees
Thousands of people visit Hurricane Ridge in Washington State's Olympic National Park each summer to gaze in awe at Mt. Olympus, but few bother to investigate the wonders at their feet.