Download Chapter 1: An introduction to Life on Earth

BIOLOGY Life on Earth
WITH PHYSIOLOGY Tenth Edition
Audesirk Audesirk Byers
1
An Introduction
to Life on Earth
Lecture Presentations by
Carol R. Anderson
Westwood College, River Oaks Campus
© 2014 Pearson Education, Inc.
Chapter 1 At a Glance
 1.1 What Is Life?
 1.2 What Is Evolution?
 1.3 How Do Scientists Study Life?
 1.4 What Is Science?
© 2014 Pearson Education, Inc.
1.1 What Is Life?
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
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1.1 What Is Life?
 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
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Figure 1-1 The cell is the smallest unit of life
nucleus
cell wall
plasma
membrane
organelles
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1.1 What Is Life?
 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
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Figure 1-2 Properties of life
Antennae and
eyes: living
things respond
to stimuli
Gut: living
things acquire
nutrients
Eggs: living
things
reproduce
© 2014 Pearson Education, Inc.
1.1 What Is Life?
 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
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Figure 1-3 The flow of energy and the recycling of nutrients
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1.1 What Is Life?
 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
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Figure 1-4 Organisms maintain relatively constant internal conditions
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1.1 What Is Life?
 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)
© 2014 Pearson Education, Inc.
1.1 What Is Life?
 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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1.1 What Is Life?
 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
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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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1.1 What Is Life?
 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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1.2 What Is Evolution?
 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%
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Figure 1-8 Chimps and people are closely related
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1.2 What Is Evolution?
 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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1.2 What Is Evolution?
 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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1.2 What Is Evolution?
 Some mutations are inherited
– Occur in sperm or egg cells
– Effects of mutation
– No effect (harmless)
– A decrease in the organism’s ability to function
– Death of the organism
– An increase in an organism’s ability to survive and
reproduce (rare)
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1.2 What Is Evolution?
 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
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1.2 What Is Evolution?
 Some inherited mutations help individuals survive
and reproduce (continued)
– Adaptations are structures, physiological processes,
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
become extinct, as for example, the dinosaurs
– Extinction is the complete elimination of a particular
species
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Figure 1-9 A fossil Tyrannosaurus rex
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1.2 What Is Evolution?
 Some inherited mutations help individuals survive
and reproduce (continued)
– 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)
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1.2 What Is Evolution?
 Some inherited mutations help individuals survive
and reproduce (continued)
– “Nothing in biology makes sense except in the light of
evolution” Dobzhansky
– Darwin and Wallace formulated the basis of our
modern understanding of evolution when they
devised the theory of evolution in the mid-1800s
– Abundant evidence has been found to support
evolutionary theory since the 1800s
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Levels of biological organization
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Fig. 1-10
1.3 How Do Scientists Study Life?
 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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1.3 How Do Scientists Study Life?
 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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1.3 How Do Scientists Study Life?
 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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1.3 How Do Scientists Study Life?
 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
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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
1.3 How Do Scientists Study Life?
 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
© 2014 Pearson Education, Inc.
1.3 How Do Scientists Study Life?
 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
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Table 1-1
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1.3 How Do Scientists Study Life?
 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
© 2014 Pearson Education, Inc.
1.3 How Do Scientists Study Life?
 Cell type distinguishes the Bacteria and Archaea
from the Eukarya (continued)
– The domains Bacteria and Archaea consist of
prokaryotic cells
– The domain Eukarya is composed of eukaryotic cells
© 2014 Pearson Education, Inc.
1.3 How Do Scientists Study Life?
 Cell type distinguishes the Bacteria and Archaea
from the Eukarya (continued)
– Two cell types are seen among all living things:
prokaryotic and eukaryotic cells
– Cell types are named after presence or absence of a
nucleus
– The nucleus is a membrane-enclosed sac containing
the cell’s genetic material
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1.3 How Do Scientists Study Life?
 Cell type distinguishes the Bacteria and Archaea
from the Eukarya (continued)
– Eukaryotic (“true nucleus” in Greek)
– They are larger than prokaryotic cells
– They contain a variety of organelles, including a
nucleus
– This cell type is found only among members of the
domain Eukarya
– They are extremely complex
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1.3 How Do Scientists Study Life?
 Cell type distinguishes the Bacteria and Archaea
from the Eukarya (continued)
– Prokaryotic (“before nucleus” in Greek)
– They are only 1–2 micrometers in diameter
– They lack organelles enclosed by membranes
– They lack a nucleus
– This cell type is found in the domains Bacteria and
Archaea
– They are smaller and much simpler than the eukaryotic
cell
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1.3 How Do Scientists Study Life?
 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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1.3 How Do Scientists Study Life?
 The Eukarya acquire energy in different ways
– Autotrophs (“self-feeding”)
– Photosynthetic organisms that capture sunlight and store it
in sugar and fats
– Includes plants, some bacteria, and some protists
– Heterotrophs (“other-feeding”)
– Organisms that acquire energy through ingesting molecules
in the bodies of other organisms
– Includes many archaeans, bacteria, protists, fungi, and
animals
– The size of the food eaten varies from individual food
molecules to ingestion and digestion of whole chunks
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1.3 How Do Scientists Study Life?
 Biologists use the binomial system to name
organisms
– Organisms are placed in a hierarchy of categories
– Genus and species are the two smallest categories
– Genus includes many different species with similar
characteristics
– Species includes organisms that can interbreed and are
nearly identical
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1.3 How Do Scientists Study Life?
 Biologists use the binomial system to name
organisms (continued)
– Binomial system based on Latin words two (bi) and
names (nomial), and consisting of the genus and
species
– Genus name is capitalized
– Both genus and species names are italicized
– People are Homo sapiens
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1.4 What Is Science?
 Science is the systematic inquiry – through
observation and experiment – into the origins,
structure, and behavior of living and nonliving
environments
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1.4 What Is Science?
 Science is based on the principle that all events
have natural causes
– The belief that some events happen through
supernatural forces (e.g., the actions of Greek gods)
– The 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
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1.4 What Is Science?
 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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1.4 What Is Science?
 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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1.4 What Is Science?
 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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1.4 What Is Science?
 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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1.4 What Is Science?
 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
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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.
1.4 What Is Science?
 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
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1.4 What Is Science?
 Scientific theories have been thoroughly tested
(continued)
– The cell theory (that all living organisms are
composed of cells) and the theory of evolution are
fundamental to the study of biology
– Natural causality is the principle that all events can be
traced to natural causes
– Natural laws apply to every time and place
– Scientific inquiry is based on the assumption that
people perceive natural events in similar ways
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1.4 What Is Science?
 Scientific theories have been thoroughly tested
(continued)
– New scientific evidence may prompt radical revision
of existing theory
– For example, the discovery of prions
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1.4 What Is Science?
 Scientific theories have been thoroughly tested (continued)
– 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)
– 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
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1.4 What Is Science?
 Scientific theories involve both inductive and
deductive reasoning
– Inductive reasoning is used in the development of
scientific theories
– A generalization is created from many observations
that support it and none that contradict it
– For example, the theory that Earth exerts gravitational
forces on objects began from repeated observations of
objects falling downward toward Earth and from no
observations of objects falling upward away from Earth
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1.4 What Is Science?
 Scientific theories involve both inductive and
deductive reasoning (continued)
– Deductive reasoning is the process of generating
hypotheses based on a well-supported generalization
(such as a theory)
– For example, based on the cell theory, any newly
discovered organism would be expected to be
composed of cells
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1.4 What Is Science?
 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
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1.4 What Is Science?
 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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1.4 What Is Science?
 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
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1.4 What Is Science?
 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
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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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1.4 What Is Science?
 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
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1.4 What Is Science?
 Knowledge of biology illuminates life
– Science is NOT a dehumanizing activity
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Figure 1-13 Adaptations in lupine flowers
Pollen is forced
onto the bee’s
abdomen
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