Transcript 1.1 Unity and Diversity

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BIOLOGY
• The study of living
organisms and their
interactions with the
environment.
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Animals
Plants
Microbes
Fungi
Ecology
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Biology
• Biology is the study of living things.
• But what is life?
• What distinguishes living from non-living
things?
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7 Properties Associated with Life
1)
2)
3)
4)
5)
6)
7)
Order
Reproduction
Growth and development
Energy processing
Response to the environment
Regulation
Evolutionary adaptation
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Order
This close-up of a sunflower illustrates the highly
ordered structure that typifies life. Living cells are
the basis of this complex organization.
Why is
order
important?
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Reproduction
• Organisms reproduce their own kind.
Here, an emperor penguin protects its
baby.
Why is
reproduction
important?
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Growth and Development
• Inherited information in the form of DNA controls the
pattern of growth and development of all organisms,
including this hatching crocodile.
Why is
DNA
important?
How do
animals
evolve?
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Energy processing
• When this bear eats its catch, it will use the chemical
energy stored in the fish to power its own activities and
chemical reactions.
Why is this
important?
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Response to the environment
• All organisms respond to environmental stimuli. This
Venus flytrap closed its trap rapidly in response to the
stimulus of a damselfly landing on it.
What does
this mean,
and why is
this
important?
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Regulation
• Many types of mechanisms regulate an organism’s internal
environment, keeping it within limits that sustain life. Here is a typical
lemur behavior with a regulatory function (sunbathing), which helps
raise the animal’s body temperature on cold mornings.
Why is this
important?
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Evolutionary adaptation
• The leaf-like appearance of this katydid camouflages it in its
environment. Such adaptations evolve over many generations as
individuals with traits best suited to their environment have greater
reproductive success and pass their traits to offspring.
Why is this
important?
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Scope of Biology
• Biology is an enormous scope, and can be
studied in two ways:
• The vertical dimension is studying biology
based on size from largest (the biosphere)
to smallest (non-living molecules).
• The horizontal dimension is studying
biology across the great diversity of
species, learning about classification of
organisms.
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THE VERTICAL DIMENSION
OF BIOLOGY
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THE BIOSPHERE
ECOSYSTEMS
COMMUNITIES
POPULATIONS
ORGANISMS
ORGANS AND ORGAN SYSTEMS
TISSUES
CELLS
ORGANELLES
MOLECULES
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THE BIOSPHERE
• The biosphere
consists of all the
environments on
Earth that are
inhabited by life. It
includes land and
water such as
oceans, lakes, and
rivers; it also includes
the atmosphere to an
altitude of several
kilometers.
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ECOSYSTEMS
• An ecosystem consists of all living things in a
particular area, along with all the nonliving
components of the environment with which life
interacts, such as soil, water, atmospheric
gases, and light. Examples of an ecosystem
are forests or coral reefs.
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COMMUNITIES
A community
is all of the
living
organisms
within a
particular
ecosystem.
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COMMUNITIES
The community of a forest includes all species of
trees, plants, animals, fungi, and bacteria that
live there.
The tree in your backyard is home to two
cardinals, a colony of ants, a wasp's nest, four
squirrels, and trillions of bacteria.
Together, all of these organisms represent a
community.
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POPULATIONS
All the
individuals
of the same
species
living within
the bounds
of a
specified
area.
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POPULATIONS
• For example, a forest may include a
population of sugar maple trees, and a
population of American black bears.
• We can now refine our definition of a
community as the set of populations that
inhabit a particular area.
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ORGANISMS
An organism is an
individual living
thing.
Each of the maple
trees and other
plants in a forest is
an organism, and so
is each forest animal
such as a frog,
squirrel, bear, and
insect.
The soil is also full of
micro organisms
such as bacteria.
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ORGANS AND ORGAN SYSTEMS
• An organ is a body part consisting of two
or more tissues.
• Examples of human organs are the brain,
heart, and kidney.
• Examples of a tree’s organs are its leaves,
stems, and roots.
• An organ system is a group of organs
which cooperate in a specific function.
• For example, the human digestive system
includes such organs as the tongue,
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stomach, and intestines
TISSUES
• A tissue is a group of similar cells which perform
the same function.
• Examples of human tissues include the
epidermis (skin), muscle, and bones.
• Leaves have one type of tissue on their surface
which contains pores to allow carbon dioxide to
reach the interior of the leaf. They have another
type of tissue within the leaf, which is the area
where of photosynthesis occurs.
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CELLS
• The cell is the fundamental unit of
structure and function of each organism.
• Some organisms are single cells.
• Other organisms, including plants and
animals, are multicellular.
– Division of labor among specialized cells.
– In humans, examples of a specialized cell
include a nerve cell (neuron), a muscle cell
(myofibril), and a bone cell (osteocyte).
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ORGANELLES
• An organelle is like a miniature organ
within a single cell.
• It has a specific function for that cell.
• An example of an organelle in a human
cell is a nucleus.
• An example of an organelle in a plant cell
is a chloroplast.
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MOLECULES
• A molecule is a chemical structure consisting of
two or more atoms.
• If one of the atoms is carbon, it is an organic
molecule.
• If there is no carbon, it is an inorganic molecule.
• An example of a plant molecule is chlorophyll.
• Examples of organic molecules used by animals
are carbohydrates, proteins, and fats.
• Examples of inorganic molecules used by
animals are salt and water.
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MOLECULES
• Life is organized in a hierarchical
fashion.
• The following sequence illustrates that
hierarchy increases in complexity:
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Hierarchy of Life
• Life is
organized in a
hierarchical
fashion.
• This illustrates
that hierarchy
increases in
complexity:
• Increasing complexity:
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Molecule
Organelle
Cell
Tissue
Organ
Organism
Population
Community
Ecosystem
Biosphere
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ECOSYSTEM DYNAMICS
Pelicans belong to a group
of animals called Aves, also
known as birds, which are
believed to have evolved
from ancient feathered
dinosaurs.
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Pelicans
• Pelicans have fishing skills that are well suited to the
ocean habitat.
• They can dive into the ocean and catch a fish the below
the surface.
• There are hunting helps regulate the size of fish
populations.
• Because it is comfortable floating on the waves, it is also
an ideal scavenger.
• Small fishing boats can therefore toss away unwanted
fish parts without polluting the water.
• But some fishermen see the birds as competition rather
than trash collectors, and a slaughter thousands of the
birds.
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Pelicans
• Additionally, when humans use pesticides, the rain
washes the pesticides into the soil, which gets carried
into the water table, which leads to the oceans, where it
accumulates in fish and birds that ate them.
• The pesticides will cause a bird to lay a very thin egg
shell so that it breaks before it hatches.
• Because of this, a pelican population was almost wiped
out.
• The birds first disappeared entirely from Louisiana and
have vanished from other coastal areas as well.
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Bird Sanctuary, Florida
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• In 1970 the brown pelican was declared an endangered
species.
• Biologists argued that only a ban on pesticides such as
DDT would save the birds, and in 1972 that ban was
enacted.
• Because of these efforts, they are once again thriving in
many coastal areas.
• However, as their numbers grow, they are continuing to
face problems when they encounter humans.
• The young pelicans on the previous slide are at a bird
sanctuary in Florida which cares for birds injured by boat
propellers or fishing lines.
• All organisms are connected to the environment and other
organisms.
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ECOSYSTEM DYNAMICS
• Each organism interacts continuously with its
environment, which includes other organisms as
well as nonliving factors.
• For example, the roots of a tree absorb water
and minerals from the soil.
• The leaves take in carbon dioxide from the air.
• Solar energy absorbed by chlorophyll drives
photosynthesis, which converts water and
carbon dioxide to sugar and oxygen.
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ECOSYSTEM DYNAMICS
• The tree releases oxygen to the air, and its
roots help form soil by breaking up rocks.
• Both the organism and the environment
are affected by the interactions between
them.
• The tree also interacts with other of life,
including soil microorganisms and animals
that eat its leaves and fruit.
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ECOSYSTEM DYNAMICS
• The dynamics of any ecosystem
include two major processes.
• One process is the cycling of nutrients.
• For example, minerals acquired by plants
will eventually be returned to the soil by
microorganisms that decompose dead
leaves, roots, and fruit.
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ECOSYSTEM DYNAMICS
• The second major process and an
ecosystem is the flow of energy from
sunlight  producers  consumers.
• Producers are plants and other
photosynthetic organisms that convert
light energy to chemical energy.
• Consumers are organisms, such as
animals, that feed on producers and
other consumers.
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Producers
Consumers
Decomposers
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ENERGY CONSERVATION
• Moving, growing, reproducing, and other
activities of life require organisms to perform
work. Work depends on a source of energy.
• The exchange of energy between an organism
and its surroundings often involves the
transformation of one form of energy to another.
• For example, when a leaf produces sugar, it
converts solar energy to chemical energy in the
form of sugar molecules.
• When an animal’s muscle cells use sugar as fuel
to power movements, they convert chemical
energy in the form of sugar to kinetic energy (the
energy of motion).
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ENERGY CONSERVATION
• During the course of these conversions of one
energy form to another, thermal energy is
dissipated to the environment in the form of
heat.
• In contrast to chemical nutrients, which recycle
within an ecosystem, energy flows through an
ecosystem, usually entering the system as light
and exiting the system as heat.
• The ultimate source of energy flowing into
nearly all ecosystems is sunlight.
• The ultimate source of energy flowing out of
nearly all ecosystems is heat.
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CELLS’ HEREDITARY
INFORMATION
• A cell is the lowest level of organization that can
perform all activities required for life.
• For example, the ability of a cell to divide and form new
cells is the basis for all reproduction and for the growth
and repair of multicellular organisms.
• Your every movement is based on the activities of your
muscle cells.
• Your every thought is based on the activities of your
nerve cells.
• Even the process of breathing is the cumulative product
of cellular activities.
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CELLS’ HEREDITARY
INFORMATION
• Within the nucleus of a cell there are
structures called chromosomes, which are
made out of DNA.
• On the chromosomes are genes, which
are the units of inheritance that transmit
information from parents to offspring.
• Your hair color, for example, is the result
of genes that you inherited on your
parents.
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CELLS’ HEREDITARY
INFORMATION
• Each chromosome is a very long DNA molecule with
hundreds or thousands of genes arranged along its
length.
• The DNA of chromosomes replicates as a cell prepares
to divide; therefore, each of the two offspring cells inherit
a complete set of genes.
• Each of us began life as a single cell stocked with DNA
inherited from our parents.
• Within the genes are molecules that encode the
information for building the entire body.
• In this way, DNA directs development and
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maintenance of the entire organism.
CELLS’ HEREDITARY
INFORMATION
• Each DNA molecule is like a chain with many links.
• Each link of the chain is one of four kinds of chemical
building blocks called nucleotides.
• The way DNA encodes a cell’s information is similar to
the way we arrange letters of the alphabet into precise
sequences with specific meanings.
• The word rat, for example, conjures up an image of a
rodent.
• The words tar and art, which contained the same letters,
mean very different things.
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DNA
• Each DNA molecule
is like a chain with
many links.
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CELLS’ HEREDITARY
INFORMATION
• Libraries are filled with books containing
information encoded in varying sequences
of only 26 letters.
• Our genetic information is likewise made
out of only four nucleotides (letters of the
alphabet); however each gene (word) may
be thousands of letters in length.
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A
DNA
C
T
A
T
A
C
C
G
• Each link of the chain
is one of four kinds of
chemical building
blocks called
nucleotides.
T
A
G
T
A
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CELLS’ HEREDITARY
INFORMATION
• Most genes program the cell’s production of large
molecules called proteins.
• Each gene codes for a different protein which has a
unique shape and function in the cell.
• One protein might be part of a muscle, while another
protein might be an antibody.
• The DNA provides the hereditary blueprint for these
proteins, but the proteins themselves are the tools that
actually build and maintain the cell.
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All organisms share a common set of features
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Regulation of internal conditions
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Growth and development
Energy use
Response to environmental stimuli
The ability to reproduce and evolve
Figure 1.4D
Figure 1.4E
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Figure 1.4B
Figure 1.4C
THE HORIZONTAL DIMENSION
OF BIOLOGY: TAXONOMY
• Taxonomy is that part of biology dedicated to
naming, describing, and classifying species.
• The categories are ordered into a series of
groups of increasing breadths.
• Until the last decade, taxonomy was divided into
five kingdoms, including the plant and animal
kingdoms.
• But with new understanding of DNA sequences,
biologists are re-evaluating the system of
classification.
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• The debate over the number of kingdoms
is still continuing, but there is a consensus
that the kingdoms of life can now be
grouped into three even higher levels of
classification called domains.
• The three domains are named Bacteria,
Archaea, and Eukarya.
• Bacteria and Archaea are both
prokaryotes (unicellular and microscopic).
• Eukaryotes are multicellular organisms,
and include the kingdoms of plants,
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animals, and fungi.
SEM 3,250
– Domains Bacteria and Archaea
SEM 25,000
Figure 1.5A
Figure 1.5B
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– Domain Eukarya includes
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Protists (protozoans and algae)
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The kingdoms Fungi, Plantae, and Animalia
Protists
(multiple kingdoms)
Kingdom Fungi
Kingdom Animalia
Kingdom
Plantae
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Who are we?
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Domain: Eukarya
Kingdom: Animal
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: sapiens
Memory Aid:
Dashing King Phillip
Came Over From
Greece, Singing
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Animals
• What’s the
difference
between an
animal and a
plant?
•
An animal can move
from one place to
another, they don’t get
food from sunlight,
and their body
structure is fixed.
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Mammals
• Mammals are
born with a
placenta and
produce milk
for the
offspring.
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Primates
• Primates have an opposable thumb (can
touch each of the other fingers).
• Good depth perception because the eyes
are in front of the head.
• Gestation (length of pregnancy) is lengthy.
• One birth at a time is the norm.
• Juvenile period of dependency is long.
• There is an emphasis on learned behavior
and complex social interactions.
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Humans and Apes
• Humans and apes are both primates.
• There are four types of modern apes:
gibbons, orangutans, gorillas, and
chimpanzees.
• Humans distinguished from modern apes by
– walking upright
– dental features
– shape of face
– brain size
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Hominids
• Make use of
symbolic language
(writing)
• Walk on two legs
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Hominids
• Evolutionists say that our ancestors are
Australopithecus, which evolved in eastern
Africa 4 MYA (million years ago).
• The most famous Australopithecus fossil is
called Lucy (The name derives from the
Beatles’ song “Lucy in the Sky with
Diamonds.”).
• Although her brain was quite small, Lucy
walked upright.
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Homo sapiens
• There is only one
genus and species of
hominids and that is
Homo sapiens.
• In Latin, Homo
sapiens means “wise
or rational man”.
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We Are One Species
• Races are actually
just slight
differences in
ethnicity that
developed as an
adaptation to the
climate of a region.
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But inside plants,
animals, fungi,
and people, our
molecules are all
the same. Thus,
there is unity
within the
diversity of life.
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Match the following to their descriptions
• Animals
• Mammals
• Primates
• Hominids
• Homo Sapiens
A. walk on two legs,
make use of symbolic
language (writing)
B. can move from one
place to another, body
structure is fixed.
C. born with a placenta
and produce milk for the
offspring.
D. wise or rational man.
E. Opposable thumb, long
gestation, learned behavior
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Match the following taxonomy
terms for a human being
•
•
•
•
•
Kingdom:
Order:
Family:
Genus:
Species:
A.
B.
C.
D.
E.
Homo
Primate
Animal
sapiens
Hominid
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EVOLUTION
AND NATURAL
SELECTION
• Charles Darwin 1859
• The Origin of Species
by Natural Selection.
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EVOLUTION AND NATURAL
SELECTION
• The history of life is documented by fossils and other
evidence that the Earth and its life forms is changing and
evolving.
• This evolutionary view of life came into sharp focus in
1859, when Charles Darwin published one of the most
controversial books ever written: The Origin of Species
by Natural Selection.
• This book articulated two main points. First, Darwin
presented evidence to support his view that modern
species arose from a succession of ancestors.
• Darwin called this “descent with modification”.
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EVOLUTION
• This book articulated two main points. First, Darwin
presented evidence to support his view of evolution –
that species living today are descendants of ancestral
species.
• Darwin called his evolutionary theory “descent with
modification”.
• This phrase captures both the unity of life (descent from
common ancestors) and the diversity of life
(modifications that evolved as species branched from
their common ancestors).
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Descent with Modification
• Descent with modification implies that modern species
arise from a common ancestor.
• As evidence for this theory, the arms of a bat, human,
horse’s forelegs, and whale flippers all contain the same
skeletal architecture, including the same bones, joints,
nerves, and blood vessels.
• In the Darwinian view, the unity of mammalian limb
anatomy indicates the inheritance of that structure from a
common ancestor, the diversity of the forelimbs having
been modified by natural selection operating over
millions of generations in different environmental
conditions.
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Descent with Modification
• Modern species arise
from a common
ancestor.
• The arms of a bat,
human, horse’s
forelegs, and whale
flippers all contain the
same skeletal
architecture.
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NATURAL SELECTION
• Darwin's second main point was to propose a
mechanism for evolution, which he called “natural
selection”.
• He started with two observations.
1) Individuals in a population vary in their traits,
many of which are passed on from parents to
offspring.
2) A population can produce far more offspring than
the environment can support.
• From these two observations, Darwin inferred that those
individuals with heritable traits best suited to the
environment are more likely to survive and reproduce
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than others.
NATURAL SELECTION
• As a result of this unequal reproductive
success over many generations, a higher
and higher proportion of individuals will
have the best traits for survival.
• The result of natural selection is
evolutionary adaptation, the accumulation
of favorable traits in a population over
time.
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Darwin
• Evolution = Descent with modification
– Modern species arose from a succession of
ancestors.
• Natural selection
– The natural environment selects for the
propagation of certain traits.
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Natural Selection
• Natural selection is when the natural environment
selects for the propagation of certain traits.
• For instance, consider an area where the soil has been
blackened by a recent brush fire. A population of insects
there contains beetles that are either white or gray; a
predator bird can easily pick out the white colored
insects and the beetles with the white coloration are
eliminated from the population.
• The survivors reproduce, carrying on their genetic
coloration, enhancing the survival and reproductive
success of the dark-colored bugs. This is natural
selection.
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Adaptations evolved
by means of natural
selection
Killer whale
Pangolin
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SCIENTIFIC METHOD
• The word “science” is derived from a Latin verb meaning
“to know”.
• At the heart of science is inquiry, a search for information
and explanation, often focusing on specific questions.
• Biology blends two main processes of scientific inquiry:
discovery science and hypothesis-based science.
• Discovery science is mostly about describing nature.
• Hypothesis-based science is mostly about explaining
nature.
• Most scientific inquiries combine these two research
approaches.
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SCIENTIFIC METHOD
• Discovery science describes natural structures
and process through careful observation and
analysis of data.
• For example, discovery science gradually built
our understanding of cell structure, and it is
currently expanding our understanding of
genetics.
• Observation is the use of senses to gather
information, sometimes with the help of tools
such as microscopes that extend our senses.
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SCIENTIFIC METHOD
• Recorded observations are called data.
– Qualitative
• recorded descriptions rather than measurements
– Quantitative
• recorded as specific measurements
• Hypothesis-based science starts with an
observation that leads to a question about the
cause or explanation for the observation.
– A hypothesis is a tentative answer to some
question.
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Hypothesis
• It is usually an educated guess based on
past experience and current knowledge.
• You notice that over the past month,
many students have started wearing a
new style of school sweatshirt.
• You think to yourself, maybe the
bookstore recently started selling this
new sweatshirt style.
• This prediction is an example of a
hypothesis.
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SCIENTIFIC METHOD
• A scientific hypothesis makes a prediction
that can be tested by designing an
experiment. We all use hypotheses in
solving everyday problems.
• Observation: your flashlight stops working.
• Question: Why doesn't the flashlight work?
• Hypotheses:
– The batteries are dead
– The bulb is burned-out
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SCIENTIFIC METHOD
• Each of these alternative hypotheses makes predictions
you can test with experiments.
• For example, the dead battery hypothesis predicts that
replacing the batteries will fix the problem.
• The experiment is to replace the batteries with new
ones.
• If the flashlight then works, the hypothesis was validated.
If the flashlight does not work, the experiment falsifies
the hypothesis.
• The second hypothesis can then be tested by replacing
the light bulb.
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SCIENTIFIC METHOD
• This example illustrates two important qualities of
scientific hypotheses.
• First, a hypothesis must be testable; there must be
some way to check out the validity of the idea.
• Second, a hypothesis must be falsifiable; there must be
some experiment that could reveal it such an idea is
actually not true.
• To be scientifically valid, a hypothesis must be
testable and falsifiable.
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Valid Hypothesis
• Hypothesis must be testable
– Must be some way to check out the validity of
the idea.
• Hypothesis must be falsifiable
– Must be some experiment that could reveal it
such an idea is actually not true
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The hypothesis-driven scientific method
Observations
Question
Hypothesis # 1:
Dead batteries
Hypothesis # 2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test prediction
Test falsifies hypothesis
Test does not falsify hypothesis
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The hypothesis-driven scientific method
Observations
Question
Hypothesis # 1:
Dead batteries
Hypothesis # 2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test prediction
Test falsifies hypothesis
Test does not falsify hypothesis
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The hypothesis-driven scientific method
Observations
Question
Hypothesis # 1:
Dead batteries
Hypothesis # 2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test prediction
Test falsifies hypothesis
Test does not falsify hypothesis
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Controlled Experiment
• Ideally, an experiment should contain a
“control” component.
• Two experiments are conducted, one
differing from the other by only a single
variable.
• The role of a control in an experiment is
to provide a basis of comparison to the
experimental group.
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Controlled Experiment
• For example, a company that sells cereal wants to prove
that it lowers cholesterol.
• They find 1000 volunteers to eat this cereal for three
months and have their cholesterol measured before and
after the experiment.
• A proper experimental design should include another
1000 volunteers who are as similar as possible to the
experimental group (in age, ethnicity, health status, etc.)
who do not eat that cereal.
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Controlled Experiment
• Another component of an ideal experiment is that all
possible variables are eliminated between the control
group and the experimental group.
• For example, if the volunteers who eat this cereal are all
in their mid-- 20s and exercise daily, and the volunteers
in the control group are middle aged and do not
exercise, there are two variables in this experiment that
were not eliminated.
• Thus, the results of the experiment are not valid.
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An Actual Case Study of
Hypothesis-Based Science
• New discoveries in science start with the
observation: Many poisonous animals are brightly
colored so that predators will recognize them as
poisonous and stay away. But there are also mimics.
These imposters look like poisonous species but are
actually harmless.
• After an observation comes a question: What is the
function of such mimicry?
• And then a hypothesis is formed: Such deception is
an evolutionary adaptation that reduces the harmless
animal’s risk of being eaten.
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Poisonous
Coral Snake
NonPoisonous
King Snake
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Hypothesis-Based Science
• In 2001, biologists David and Karin Pfenning, along with
William Harcombe, one of their students, designed an
experiment to test the hypothesis that “mimics benefit
because predators confuse them with the harmful
species”.
• A poisonous snake called the eastern coral snake has
colored rings of red, yellow, and black.
• Predators rarely attack these snakes.
• The predators do not learn this avoidance behavior by
trial and error; a first encounter with a coral snake would
usually be deadly.
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Hypothesis-Based Science
• Therefore, natural selection has apparently increased
the frequency of predators that inherit an instinctive
ability to recognize the coloration of the coral snake.
• A non-poisonous snake called the scarlet king snake
mimics the ring coloration of the coral snake.
• (Humans can remember the difference by this phrase:
red and yellow kill a fellow, red and black venom lack).
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• Both types of snakes live in North and South Carolina,
but the king snake’s geographical range also extends into
regions where no coral snakes are found.
• This makes it possible for researchers to test a key
prediction of the mimicry hypothesis: Mimicry should help
protect king snakes from predators, but only in regions
where coral snakes also live.
• Avoiding snakes with warning coloration is an adaptation
of predator populations that have evolved in areas where
the poisonous coral snakes are present.
• The mimicry hypothesis predicts that predators adapted
to the warning coloration of coral snakes will attack king
snakes less frequently then will predators in areas where
coral snakes are absent.
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Hypothesis-Based Science
• The researchers placed equal numbers of artificial brown
snakes and artificial coral snakes in field sites throughout
North and South Carolina, including the region where
coral snakes are absent.
• After four weeks, they retrieved the fake snakes and
recorded how many had been attacked by looking for a
bite or claw marks.
• The most common predators were foxes, coyotes, and
raccoons, but Black Bears also attacked some of the
artificial snakes.
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Artificial Snakes
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Hypothesis-Based Science
• The data fit the key prediction of the
mimicry hypothesis.
• Compared to the brown artificial snakes,
the ringed snakes were attacked by
predators less frequently only in field sites
within the geographic range of the
poisonous coral snakes.
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Hypothesis-Based Science
• This case study provides an example of a controlled
experiment, one that is designed to compare an
experimental group (the artificial king snakes) with a
control group (the artificial brown snakes).
• Ideally, the experimental and control groups differ
only in the one factor the experiment is designed to
test-- in our example, the effect of the snake’s coloration
on the behavior of predators.
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Hypothesis-Based Science
• Without the control group, the researchers would not
have been able to rule out the number of predators in a
different test areas as the cause of the different numbers
of attacks on the artificial king snakes.
• The clever experimental design left coloration as the only
factor that could account for the low predation rate on
the artificial king snakes placed within the range of coral
snakes.
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SCIENCE, TECHNOLOGY, AND
SOCIETY
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Endangered species
Genetically modified crops
Global warming
Air and water pollution
The cloning of embryos
Nutrition controversies
Emerging diseases
Medical advances
is there ever a day that we
don't see several of these
issues featured in the
news? Biology, the
science of life, has an
enormous impact on our
everyday life.
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103
SCIENCE, TECHNOLOGY, AND
SOCIETY
• The goal of science is to understand natural phenomena.
• In contrast, technology generally applies scientific
knowledge for some specific purpose. Science and
technology can benefit society.
• The discovery of the structure of DNA 50 years ago has
led to the many technologies of DNA engineering that
are being used today in the field of medicine, agriculture,
and genetics.
• The direction that technology takes depends on the
wants and needs of people and on the social
environment of the times.
104
SCIENCE, TECHNOLOGY, AND
SOCIETY
• With advances in technology come difficult
choices.
• For example, under what circumstances is it
acceptable to use DNA technology to check if
people have genes for hereditary diseases?
• Should such tests always be voluntary, or are
there any circumstances when genetic testing
should be mandatory?
• Should insurance companies or employers have
access to the information?
105
SCIENCE, TECHNOLOGY, AND
SOCIETY
• Technology has improved our standard of living
in many ways, but not without consequences.
• Technology that keeps people healthier has
enabled the earth's population to double to over
6 billion in just the past 40 years.
• The environmental effects of this growth can be
devastating.
• Global warming, toxic wastes, acid rain,
deforestation, nuclear accidents, and extinction
of species are just some of the repercussions.
106
SCIENCE, TECHNOLOGY, AND
SOCIETY
• Science can help us identify such problems and
provide insight into what course of action may
prevent further damage.
• But solutions to these problems have as much to
do with politics, economics, and cultural values
as with science and technology.
• Therefore, every citizen has a responsibility to
develop a reasonable amount of scientific
literacy.
107
SCIENCE, TECHNOLOGY, AND
SOCIETY
• Whether you are a scientist or not, issues come
up at the poll booth for a vote and all citizens
should be educated about how science works
and about the potential benefits and risks of
specific technology.
108
SCIENCE, TECHNOLOGY, AND
SOCIETY
• From the molecules to the biosphere, biology is
directly connected to our everyday lives.
• This course will give you an education about the
science of life and help you apply that
understanding to evaluate issues ranging from
your own personal health to the well-being of the
whole world.
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