Transcript Learning about Human Biology Chapter 1 1.1 The Characteristics of

Learning about Human Biology
Chapter 1
1.1 The Characteristics of Life
Focus: Several basic characteristics
allow us to distinguish between
living things and nonliving objects.
The Characteristics of Life

Living things take in energy and materials

Energy: the capacity to do work

Living things sense and respond to changes in
the environment

Living things reproduce and grow

Living things consist of one or more cells

Living things maintain homeostasis
Humans Take in Energy by Eating Food
Cells Are the Basic Units of Life
Summary of Life’s Characteristics
1.2 Our Place in the Natural World
Focus: Human beings arose as a
distinct group of animals during an
evolutionary journey that began
billions of years ago.
Humans Have Evolved over Time
 Evolution – change in the body plan and functioning
of organisms through the generations
• Began billions of years ago
• Continues today
 Where do we fit in?
• Primates
• Vertebrates
 Classification of living organisms
• Three domains of life
• Five kingdoms of life – changing as we speak!
Animation: Life’s diversity
Humans Are Related to Earth’s Other
Organisms
Humans Have Some Distinctive Characteristics
 Mammalian features
• Hair
• Mammary glands
 Distinctive PRIMATE features
• Manual dexterity
• Brain
• Size
• Capacity for sophisticated language and analysis
• Development of various social behaviors
1.3 Life’s Organization
Focus: Nature is organized on many
levels, starting with nonliving
materials and eventually including
the whole living world.
Fig. 1-5a, p. 4
Fig. 1-5b, p. 5
Animation: Life’s levels of organization
Animation: Building blocks of life
Organisms Are Connected through the
Flow of Energy and Cycling of Materials
 Solar energy and photosynthesis
 Interconnections among organisms
• Producers
• Consumers
• Decomposers
• bacteria and fungi
The Flow of Energy and the Cycling of
Materials Maintain Nature’s Organization
Animation: One-way energy flow and
materials cycling
1.4 Using Science to Learn about
the Natural World
Focus: Science basically is a way of
thinking about the natural world by
making and testing predictions they
search for evidence that may disprove or
support a proposed explanation.
Science Is a Systematic Study of Nature
 Scientific method
• Observe some aspect of nature
• Ask a question about the observation or identify
a problem to explore
• Develop a hypothesis
• Make a prediction
• Test the prediction
• Repeat the tests or develop new ones
• Analyze and report the test results and
conclusions
Scientists Do Research in the Laboratory
and in the Field
Animation: Sampling error
Example Experiment:
 Hypothesis: Olestra® causes intestinal cramps
• Variables
• Independent
• Dependent
• Standardized
• Groups
• Control
• Experimental
Hypothesis
Olestra® causes intestinal cramps.
Prediction
People who eat potato chips made with Olestra will be
more likely to get intestinal cramps than those who eat
potato chips made without Olestra.
Experimental Group
Eats Olestra
potato chips
Experiment
Control Group
Eats regular
potato chips
Results
93 of 529 people 89 of 563 people
get cramps later get cramps later
(17.6%)
(15.8%)
Conclusion
Percentages are about equal. People who eat potato chips
made with Olestra are just as likely to get intestinal cramps
as those who eat potato chips made without Olestra.
These results do not support the hypothesis.
Fig. 1-8, p. 7
Science Never Stops
 Is more research needed on Olestra?
 Olestra reformulated to reduce side effects?
Examples of Scientific Theories
Animation: An example of the scientific
method
1.5 Critical Thinking in Science
and Life
Focus: To think critically, we
must evaluate information
before accepting it.
A Guide to Critical Thinking
Evaluate the Source of Information
 Let credible scientific evidence, not opinions or
hearsay, do the convincing
 Question credentials
 Question motives
Evaluate the Content of Information
 Fact versus opinion
 Cause versus correlation
• Ice cream & crime
1.6 Science in Perspective
Focus: A scientific theory
explains a large number of
observations.
What the Word “Theory” Means in Science
 Supported by tens of thousands of experiments
 May be modified or even rejected upon further
investigations
• Science is tentative!
Science Has Limits
 External world is testing ground for scientific
views
• Natural world only (not supernatural)
 Culture and society: NOT a part of science!
• Morals
• Esthetics
• Religious beliefs
1.7 Living in a World of Infectious
Disease
Focus: Humans have always lived
with countless health threats. Today
we are locked in an escalating
global battle with bacteria, viruses,
parasites, and other pathogens agents that can cause disease.
Black Death
Infections Are a Threat Because They
Disrupt Homeostasis
 Infection – pathogen enters cells or tissues and
reproduce
 Disease – when the pathogen overwhelms the
host’s defense systems
 Effect on homeostasis
• Major versus minor disruptions
What Do Pathogens Look Like?
 Bacteria
 Viruses
 Fungi
 Parasitic protists
 Parasitic worms
A Wide Variety of Pathogens May Live on
or in the Human Body
Emerging Diseases Present New Challenges
 Causative agents of emerging diseases
•
•
•
•
West Nile virus: encephalitis
SARS virus: severe acute respiratory syndrome
Ebola virus: hemorrhagic fever
Borrelia burgdorferi bacterium: Lyme disease
The SARS and Ebola Viruses
Antibiotics Are a Double-Edged Sword
 Discovered in the 1940s
 Organisms that produce antibiotics
• natural chemicals that can destroy bacteria
 Antibiotic resistance is a major health threat
• Caused by abuse or improper use
Scientific Method Review
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