Human Biology
Sylvia S. Mader
Michael Windelspecht
Chapter 1
Exploring Life
and Science
Lecture Outline
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Points to ponder
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What is biology?
What characterizes life?
How do we classify life?
Where do humans fit into the big picture?
How do we study science?
Where is scientific information published
and what should you be aware of?
1.1 The characteristics of life
What characteristics are shared by
living organisms?
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Organized from the atom to the biosphere
Use materials and energy from the environment
Reproduce offspring
Growth and development
Maintain a relatively constant internal
environment (homeostasis)
• Respond to internal and external stimuli
• Evolutionary history through which organisms
change over time
1.1 The characteristics of life
How are living things organized?
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Biosphere
Regions of the Earth’s crust,
waters, and atmosphere inhabited
by living things
Ecosystem
A community plus the physical environment
Community
Interacting populations in a particular area
Population
Organisms of the same species
in a particular area
Organism
An individual; complex individuals
contain organ systems
nervous system
shoot system
Organ System
Composed of several organs
working together
brain
leaf
Organ
Composed of tissues functioning
together for a specific task
nervous tissue
photosynthetic tissue
Tissue
A group of cells with a common
structure and function
neuron
Cell
The structural and functional
unit of all living things
Molecule
Union of two or more atoms
of the same or different elements
Atom
Smallest unit of an element composed of
electrons, protons, and neutrons
plant cell
1.2 Humans are related to other animals
How do we classify humans?
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Human
Eukarya
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo
sapiens
House cat
Eukarya
Animalia
Chordata
Mammalia
Carnivora
Felidae
Felis
domesticus
1.2 Humans are related to other animals
What distinguishes humans?
• Cultural heritage or patterns of our behavior
passed from one generation to the next
• Highly developed brains
• Completely upright stance
• Creative language skills
• Varied tool use
• Modification of our environment for our own
purpose which may threaten the biosphere
1.3 Science is a process
What do we know about science?
• Science is a way of knowing about the natural
world
• Science and scientists should be objective
• Scientific conclusions may change or be
modified as our understanding and technology
increase
• Science is studied using the scientific method
1.3 Science is a process
Scientific Theories in Biology
1.3 Science is a process
The steps of the scientific method
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Observation
New observations
are made, and previous
data are studied.
Hypothesis
Input from various sources
is used to formulate a
testable statement.
Experiment/Observations
The hypothesis is
tested by experiment
or further observations.
Conclusion
The results are analyzed,
and the hypothesis is
supported or rejected.
Scientific Theory
Many experiments and
observations support a
theory.
1.3 Science is a process
How the Cause of Ulcers Was Discovered:
The scientific method in action
• Observations: many patients had a particular bacterium
near their ulcers
• Hypothesis: Helicobacter pylori is the cause of gastritis
and ulcers.
• Experiment/observations:
1st – H. pylori was isolated and grown from ulcer
patients
2nd – humans swallowing a H. pylori solution resulted in
inflammation in their stomachs
• Conclusion: H. pylori was the cause of most ulcers and
can be cured by antibiotics
1.3 Science is a process
A controlled study
• Variables:
• Experimental variable is the variable that is purposely
changed or manipulated
• All other variables need to remain constant
• Groups:
• Test group is a group of subjects that are exposed to
the experimental variable
• Control group is a group for comparison that is not
exposed to the experimental variable
1.3 Science is a process
A controlled study in action
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a.
State Hypothesis:
Antibiotic B is a better treatment for
ulcers than antibiotic A.
Large number
of subjects
were selected.
Subjects were
divided into
three groups.
b.
Perform Experiment:
Groups were treated the same
except as noted.
Controlgroup:
received
placebo
c.
Conclusion:
Hypothesis is
supported:
Antibiotic B is
a better
treatment for
ulcers than
antibiotic A.
Testgroup 2:
received
antibiotic B
Collect Data:
Each subject was examined
for the presence of ulcers.
Effectiveness of Treatment (%)
d.
Testgroup 1:
received
antibiotic A
100
80
80
60
60
40
20
10
0
Control
Group
Test
Group 1
Test
Group 2
(a-b): © blickwinkel/Alamy; (c): © Phanie/ Photo Researchers, Inc.
1.3 Science is a process
Reading about scientific information
• Scientific journals are considered the best
source of information but can be difficult for the
lay person to understand
• Often the lay person reads secondary sources
and must be wary of information taken out of
context
• Be careful of information on the Internet by using
reliable sources such as URLs with .edu, .gov
and .org
1.4 Making sense of a scientific study
What should you look for when you
read about science?
• Beware of anecdotal data
• Understand methodology and results
• Does the data justify the conclusions
inferred by the scientists?
• Be able to read a graph
• Have some understanding of statistics
1.4 Making sense of a scientific study
Reading a Graph
What information does this line graph convey?
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Y-axis
Diameter of Trees (cm)
130
standard error
120
Data
110
100
Site 1
Site 2
Site 3
X-axis
Site 4
1.5 Science and social responsibility
Does science have social
responsibilities?
• Science is a way of acquiring knowledge about the
natural world through a systematic process
separating it from ethics, religion and aesthetics
• Technology is the application of scientific
knowledge to human interests
- Biotechnology (genetically modified bacteria and
genetically modified crops)
- Gene technology (cloning of humans or gene therapy to
modify inheritance)
- Use of stem cells from embryos (embryonic stem cells)
1.5 Science and social responsibility
Everyone is Responsible
• The Western world believes that science
and technology improves our lives.
• All citizens should assume responsibility.
• Everyone needs to be involved in making
value judgments about the proper use of
technology.
• You will learn more about all of these as
you venture through this text. Consider
your opinions.