Download Chapter 1: An introduction to Life on Earth

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BIOLOGY Life on Earth
WITH PHYSIOLOGY Tenth Edition
Audesirk Audesirk Byers
An Introduction
to Life on Earth
Lecture Presentations by
Carol R. Anderson
Westwood College, River Oaks Campus
© 2014 Pearson Education, Inc.

Why Study Biology?
 Biology helps you to understand your body.
▪ How behavior affects health
▪ How diseases do their damage
 Biology helps you to become an informed citizen.
▪ Pollution
▪ Modified foods
▪ Extinction
▪ Cloning
▪ Human stem cell research
▪ Cures for diseases
▪ Population control
 Career opportunities
▪ Biotechnology, pharmaceuticals, medical equipment
▪ Allied health
▪ Wild life manager, forester, environmental consultant
▪ Law (environmental, patent, medical malpractice)
▪ Research
▪ Teaching
 Biology can enrich your appreciation of the world.
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1.1 What Is Life?
1.2 What Is Evolution?
1.3 How Do Scientists Study Life?
1.4 What Is Science?
Biology comes from the Greek words “bio” meaning “life” and
“logy” meaning “the study of.” Organisms share common
characteristics that, taken together, define life. Organisms:
 Acquire and use materials and energy
 Actively maintain organized complexity
 Perceive and respond to stimuli
 Grow
 Reproduce
 Have the capacity to evolve, collectively

Organisms acquire and use materials and energy
 Materials and energy are required for organisms to
maintain organization, to grow, and to reproduce
 Important materials (minerals, water, & other simple
chemical building blocks) are acquired from the air,
water, soil, and bodies of other living things
 Organisms use energy continuously to sustain
themselves
Figure 1-2 Properties of life
•The waterflea is alive.
Antennae and
eyes: living
things respond
to stimuli
Gut: living
things acquire
nutrients
Eggs: living
things
reproduce
•This waterflea is both organized and complex.
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Characteristics of living things
 This wave is complex but not organized.
 It is not alive.

Organisms acquire and use materials and
energy (continued)
 Organisms obtain energy in two ways, coming
directly or indirectly from the sun
▪ Photosynthesis is the process by which plants and some
single-celled organisms capture sunlight
▪ Other organisms consume energy-rich molecules in the
bodies of other organisms
Figure 1-3 The flow of energy and the recycling of nutrients
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Organisms actively maintain organized
complexity
 Living things use energy on a continuous basis to
self-sustain
▪ Cells pump chemicals in and out for appropriate
chemical reactions to occur
▪ Organisms maintain relatively constant internal
conditions or homeostasis
Figure 1-4 Organisms maintain relatively constant internal conditions
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Organisms perceive and respond to stimuli
 Organisms sense and respond to internal and
external environmental stimuli
▪ Sensory organs in animals can detect and respond to
external stimuli such as 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 grow toward the light, and bacteria move toward
available nutrients in a medium)

Organisms grow
 Every organism becomes larger over time
▪ Plants, birds, and mammals grow by producing more
cells to increase their mass
▪ Bacteria grow by enlarging their cells; they divide in half
to reproduce after genetic material is copied
 Growth involves the conversion of acquired
materials to molecules of the organism’s body
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Organisms reproduce
 Organisms reproduce by dividing in half,
producing seeds, bearing live young, and laying
eggs
 Organisms give rise to offspring of the same type
 The parent’s genetic material (DNA) is passed on
to the offspring, creating continuity of life
Figure 1-6 Organisms reproduce
Dividing Streptococcus
bacterium
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Dandelion producing
seeds
Panda with its baby
Figure 1-7 DNA
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Organisms, collectively, have the capacity to
evolve
 Evolution is the process by which modern
organisms descended, with modifications, from
preexisting forms of life
 Changes in DNA within populations occur over
the course of generations, which results in
evolution
▪ Populations are groups of the same type of organism
living in the same area
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Evolution explains the diversity of life on
Earth
Evolution provides an explanation for the
similarities found among different types of
organisms
 Chimpanzees and people have various physical
features in common
 DNA of humans differs from that of chimpanzees
by less than 5%
Figure 1-8 Chimps and people are closely related
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Fig. 1-10
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Life can be studied at different levels
 All matter is formed of elements
▪ An atom is the smallest particle of an element retaining
the properties of an element
▪ Atoms combine to form molecules
▪ Molecules provide the building blocks for cells, the
smallest unit of life
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The cell is the basic unit of life
 It is separated from its surroundings by a
membrane
 It encloses a variety of structures and chemicals in
a fluid environment
Figure 1-1 The cell is the smallest unit of life
nucleus
cell wall
plasma
membrane
organelles
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Life can be studied at different levels
(continued)
 Some forms of life consist of single cells
 In multicellular forms, cells combine to form
tissues
 Tissues combine to form organs, which can be
united as organ systems
 Multicellular organisms are composed of multiple
organ systems
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Life can be studied at different levels
(continued)
 Organisms of the same type that are capable of
interacting and interbreeding are called a species
 A group of organisms of the same species living in
a given area is a population
 Interacting populations make up a community
▪ A community and its nonliving environment is an
ecosystem
▪ The entire surface of Earth, including living and
nonliving components, is the biosphere
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Biologists classify organisms based on their
evolutionary relationships
 Scientists generally categorize organisms into
three major groups, or domains
▪ Bacteria
▪ Archaea
▪ Eukarya
 The fundamental differences among cell types in
organisms are reflected in classifications
Figure 1-11 The domains and kingdoms of life
DOMAIN BACTERIA
DOMAIN ARCHAEA
FIRST CELLS
Plants
Fungi
Animals
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DOMAIN EUKARYA
Protists
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Biologists classify organisms based on their
evolutionary relationships (continued)
 Bacteria and Archaea are single, simple cells
 Eukaryotic organisms have one or more extremely
complex cells
▪ The domain Eukarya contains four subdivisions or kingdoms
▪
▪
▪
▪
Fungi
Plantae
Animalia
Protists
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Biologists classify organisms based on their evolutionary
relationships (continued)
 Three characteristics underlie the classification of an organism
into a domain and kingdom
 There are exceptions to any simple set of rules used to
distinguish the domains and kingdoms, but three
characteristics are particularly useful
▪ Cell type—simple or complex
▪ The number of cells in each organism—unicellular or multicellular
▪ Energy acquisition

Cell type distinguishes the Bacteria and
Archaea from the Eukarya
▪ All cells share common features
▪ Plasma membrane is a thin sheet of molecules
surrounding the cell
▪ Organelles are specialized structures that carry out
specific functions
▪ All cells contain DNA, the hereditary material
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Multicellularity occurs only among the
Eukarya
 Unicellular (single-celled) organisms are found in
▪ Bacteria
▪ Archaea
 Multicellular (many-celled) organisms are found
in Eukarya, within the kingdoms
▪ Fungi
▪ Plantae
▪ Animalia
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Three natural processes underlie evolution
 Genetic variation among members of a
population due to differences in their DNA
 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
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Mutations are the original source of
differences in DNA
 Variations are due to the differences in genes,
which are components of DNA and the basic units
of heredity
 Mutations occur when changes in genes are
mistakenly copied
 Mutations can also result from DNA damaged by
▪ UV rays from sunlight and toxic chemicals from
cigarette smoke
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Some inherited mutations help individuals
survive and reproduce
 Natural selection is the process by which
organisms with certain inherited traits survive and
reproduce better than others in a particular
environment
▪ Organisms that best meet environmental challenges
leave the most offspring
▪ Natural selection preserves genes that help organisms
flourish
Figure 1-9 A fossil Tyrannosaurus rex
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Science is the systematic inquiry – through
observation and experiment – into the
origins, structure, and behavior of living and
nonliving environments
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The scientific method is an important tool of scientific
inquiry
 The scientific method consists of six interrelated elements
▪ Observation
▪ Question
▪ Hypothesis
▪ Prediction
▪ Experiment
▪ Conclusion
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The scientific method is an important tool of
scientific inquiry (continued)
 Scientific inquiry is a rigorous method for making
observations
 The scientific method for inquiry follows six steps
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The six steps of scientific inquiry
1. Observation of a specific phenomenon
2. The observation, in turn, leads to a question
3. The question leads to formulation of a
hypothesis, based on previous observations,
which is offered as an answer to the question
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The six steps of scientific inquiry (continued)
4. The hypothesis leads to a prediction, which is
the expected outcome of testing if the
hypothesis is correct
5. The prediction is tested by carefully designed
additional observations or carefully controlled
manipulations called experiments
6. The experiments produce results that either
support or refute the hypothesis, allowing the
development of a conclusion
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Biologists test hypotheses using controlled experiments
 Two types of situations are established
▪ A baseline or control situation in which all possible
variables are held at a constant
▪ An experimental situation in which one factor, variable, is
manipulated to test the hypothesis to determine that this
variable is the cause of an observation
 Science is useless unless communicated
▪ The scientific method is illustrated by experiments by
Francesco Redi and Malte Andersson
Figure E1-1 The experiment of Francesco Redi illustrates the scientific method
Observation: Flies swarm around meat left in the open; maggots appear on the meat.
Question:
Where do maggots on the meat come from?
Hypothesis:
Flies produce the maggots.
Prediction:
IF the hypothesis is correct, THEN keeping the flies away from the meat
will prevent the appearance of maggots.
Experiment:
Obtain identical pieces of
meat and two identical jars
Place meat
in each jar
Leave the jar
uncovered
gauze prevents the
entry of flies
Leave exposed
for several days
Controlled variables:
Flies swarm around
and maggots appear
Results
Control situation
Conclusion:
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Experimental variable:
time, temperature,
place
Cover the jar
with gauze
Leave covered
for several days
Flies are kept from
the meat;
no maggots appear
Experimental situation
The experiment supports the hypothesis that flies are the source of
maggots and that spontaneous generation of maggots does not occur.
Figure E1-2 The experiment of Malte Andersson
Observation: Male widowbirds have extremely long tails.
Question:
Why do males, but not females, have such long tails?
Hypothesis:
Males have long tails because females prefer to mate with long-tailed males.
Prediction:
IF females prefer long-tailed males, THEN males with artificially lengthened tails will attract more mates.
Experiment:
Divide male birds
into four groups
Manipulate the
tails of the males
Do not
change the tail
Cut the tail and
re-glue in place
Experimental
variable:
Cut the tail to half of
the original length
Add feathers to
double the tail length
Release the males,
wait a week,
count the nests
Release the males,
wait a week,
count the nests
Average of less
than half a nest
per male
Average of
About two nests
per male
length of tail
Release the males,
wait a week,
count the nests
Release the males,
wait a week,
count the nests
Average of
about one nest
per male
Average of
about one nest
per male
Control groups
Conclusion:
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Controlled
variables:
location, season,
time, weather
Results
Experimental groups
The hypothesis that female widowbirds prefer to mate with long-tailed males (and are less likely to mate
with short-tailed males) is supported.
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Scientific theories have been thoroughly
tested
 A scientific theory is a general and reliable
explanation of important natural phenomena that
has been developed through extensive and
reproducible observations and experiments
 A scientific theory is best described as a natural
law, a basic principle derived from the study of
nature, which has never been disproven by
scientific inquiry

Scientific theories are formulated in ways
that can potentially be disproved
 Basic principles of science are referred to as
theories because theories can be disproved or
falsified
 Falsifying theories is distinctly different between
scientific theories and faith-based beliefs
▪ “Each creature on Earth was separately created” cannot
be subjected to scientific inquiry because it is a belief
rooted in faith

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
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Science is a human endeavor (continued)
 In the 1920s, bacteriologist Alexander Fleming
grew bacteria in cultures
 One of the bacterial cultures became
contaminated with a mold
 Fleming was about to destroy the culture when he
noticed the mold (Penicillium) inhibited bacterial
growth in the culture

Science is a human endeavor (continued)
 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
Figure 1-12 Penicillin kills bacteria
A Petri dish
contains solid
growth medium
Bacteria grow in
dense red colonies
on the growth medium
A substance diffuses
from the mold and
kills the bacterial
colonies, which lose
their color as they die
A colony of the
mold Penicillium
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Science is a human endeavor (continued)
 Fleming continued beyond a lucky “accident” with
further scientific investigation to a great discovery
 “Chance favors the prepared mind” Louis Pasteur