Transcript chapter1

Invitation to Biology
Chapter 1
Biology Concepts and Applications, Eight Edition, by Starr, Evers, Starr. Brooks/Cole,
Cengage Learning 2011.
Biology, Ninth Edition, by Solomon, Berg, Martin. Brooks/Cole, Cengage Learning 2011.
1.1 Life’s Levels of Organization
 Nature has levels of organization
 Unique properties emerge at successively
higher levels
 Atoms are organized into molecules
 In multicelled species, cells are organized into
tissues, organs, and organ systems
 All organisms consist of one or more cells
Organization of Groups of Organisms
 Population
• All individuals of one species in a specific area
 Community
• All populations in a specific area
 Ecosystem
• A community interacting with its environment
 Biosphere
• All regions of Earth that hold life
• Land, water, and atmosphere
Levels of Organization
Levels of Organization
KEY CONCEPTS:
LEVELS OF ORGANIZATION
 We study the world of life at different levels of
organization, from atoms and molecules to the
biosphere
 “Life” emerges at the level of cells
1.2 Overview of Life’s Unity
 Organisms require energy and materials to sustain
their organization and activities
• Nutrients are required for growth and survival
• Producers make their own food
• Consumers eat other organisms
 Ecosystems also depend on continuous energy
input
• There is a one-way flow of energy through ecosystems
• Organisms can neither create energy or use it with
complete efficiency
• During every energy transaction, some energy
disperses into the environment as heat
The Producers
 Plants, algae, and some bacteria are producers
(autotrophs) that produce their own food from simple
raw materials
 Most producers use sunlight as energy for
photosynthesis, which transforms light energy into
chemical energy stored in chemical bonds of food
molecules
 Photosynthesis synthesizes food molecules such as
glucose (sugar) from carbon dioxide and water, and
releases oxygen:
carbon dioxide + water + light → glucose + oxygen
The Consumers
 Animals are consumers (heterotrophs) that obtain
energy by breaking down food molecules produced in
photosynthesis
 Primary consumers eat producers; secondary
consumers eat primary consumers
 Chemical bonds are broken in the process of cellular
respiration, and stored energy is made available:
glucose + oxygen →
carbon dioxide + water + energy
The Decomposers
 Most bacteria and fungi are decomposers,
heterotrophs that obtain nutrients by breaking
down nonliving organic material such as
wastes, dead leaves and branches, and bodies
of dead organisms
 In the process of obtaining energy,
decomposers make the components of these
materials available for reuse
Energy Flow Within
and Among Organisms
Ecosystem:
Energy Flow and Material Cycling
Overview of Life’s Unity
 Organisms sense change
• Receptors respond to stimulation
• Responses keep internal conditions within ranges
that cells can tolerate (homeostasis)
Response to Stimulus
Overview of Life’s Unity
 Organisms grow and reproduce
• Based on information encoded in DNA
• Inheritance transmits DNA from parents to
offspring through reproduction mechanisms
• Development transforms first cell into an adult
Organisms Grow and Develop
• Biological growth involves an increase in size of
individual cells of an organism, in number of cells, or
in both
• Some organisms (e.g. trees) grow throughout
their lives
• Many animals have a growth period that ends at
adult size
• Development includes all changes during an
organism’s life
• Example: A human develops from a fertilized egg
into a multicellular organism with structures and
body form adapted to specific functions
Development
Organisms Regulate
Their Metabolic Processes
 Metabolism includes all chemical activities that take
place in an organism, including chemical reactions
essential to nutrition, growth and repair, and
conversion of energy
 Homeostatic mechanisms carefully regulate
metabolic processes to maintain an appropriate,
balanced internal environment (homeostasis)
• Example: Regulation of blood sugar (glucose)
Instructions Assemble Materials
KEY CONCEPTS:
LIFE’S UNDERLYING UNITY
 All organisms are alike in key respects:
• Consist of one or more cells
• Live through inputs of energy and raw materials
• Sense and respond to changes in their external
and internal environments
• Cells contain DNA (molecule that offspring inherit
from parents; encodes information necessary for
growth, survival, and reproduction)
1.3 So Much Unity, So Many Species
 The world of life, past and present, shows great
diversity
 Classification systems organize species in ever
more inclusive groups
 Taxonomy, is the science of naming and
classifying organisms
Genus and Species
 Species: One kind of organism
• A species is a group of organisms with similar
structure, function, and behavior
Binomial System
 The binomial system of nomenclature is used
to name each species, it is called such because
each species has a two-part name
 The first part of the name is the genus
• Closely related species are grouped into a genus
(genera)
 The second part, the specific epithet,
designates a particular species in that genus
• Example: The domestic dog, Canis familiaris (or
C. familiaris), and timber wolf, Canis lupus (C.
lupus), are in the same genus
Taxonomic Classification
is Hierarchical
 Related genera are grouped in a family
 Families are grouped into orders, orders into
classes, and classes into phyla (phylum)
 Phyla are assigned to kingdoms, and kingdoms
are grouped in domains
 Each level is a taxon (taxa)
Classification of the Cat, Human,
and White Oak Tree
Table 1-1, p. 11
DOMAIN
Eukarya
KINGDOM
Animalia
PHYLUM
Chordata
CLASS
Mammalia
ORDER
Primates
FAMILY
Pongidae
GENUS
Pan
SPECIES
Pan troglodytes
Fig. 1-10, p. 12
Domains
 Current classification groups all species into
three domains
• Bacteria (single-celled prokaryotes)
• Archaea (single-celled prokaryotes)
• Eukarya (protists, plants, fungi, and animals)
Life’s Three Domains
Domain Bacteria
Domain Archaea
(a) The large,
rod-shaped
bacterium Bacillus
anthracis, a
member of domain
Bacteria, causes
anthrax, a disease
of cattle and sheep
that can infect
humans.
(b) These
archaea
(Methanosarcina
mazei), members
of the domain
Archaea, produce
methane.
Bacteria
Archaea
Domain Eukarya
(c) These
unicellular
protozoa
(Tetrahymena)
are classified in
one of the
protist groups.
Protists
Common ancestor
of all organisms
(d) Plants
include many
beautiful and
diverse forms,
such as the
lady’s slipper
(Phragmipedium
caricinum).
(e) Among the
fiercest animals,
lions (Panthera
leo) are also
among the
most sociable.
The largest of the
big cats, lions live
in prides (groups).
Plants Animals
(f) Mushrooms,
such as these
fly agaric
mushrooms
(Amanita
muscaria), are
fungi. The fly
agaric is
poisonous and
causes delirium,
raving, and
profuse sweating
when ingested.
Fungi
KEY CONCEPTS:
LIFE’S DIVERSITY
 The world of life shows great diversity
 Many millions of kinds of organisms (species)
have appeared and disappeared over time
 Each species is unique in at least one trait—in
some aspect of its body form or behavior
1.4 An Evolutionary View of Diversity
 Life’s diversity arises from mutations
• Changes in molecules of DNA which offspring
inherit from their parents
 In natural populations, mutations introduce
variation in heritable traits among individuals
Variation in Heritable Traits
 Some trait forms are more adaptive than others
• Bearers are more likely to survive and reproduce
 Over generations, adaptive forms of traits tend
to become more common in a population
• Less adaptive forms of the same traits become
less common or are lost
Evolution
 Populations evolve
• Traits that help characterize a population (and a
species) can change over generations
 Evolution
• Change which occurs in a line of descent
Selection
 Natural selection
• In natural populations
• Differential survival and reproduction among
individuals that vary in one or more heritable traits
 Artificial selection
• Breeding of captive populations
• Traits selected are not necessarily adaptive
KEY CONCEPTS:
EXPLAINING UNITY IN DIVERSITY
 Theories of evolution (especially a theory of
evolution by natural selection) help explain why
life shows both unity and diversity
 Evolutionary theories guide research in all fields
of biology
1.5 Critical Thinking and Science
 Critical thinking is a self-directed act of judging
the quality of information as one learns
 Science is a way of looking at the natural world
• Helps minimize bias in judgments
• Focuses on testable ideas about observable
aspects of nature
Evidence-Based Thinking
1.6 How Science Works
 Researchers generally
• Observe something in nature
• Form hypotheses (testable assumptions) about it
• Make predictions about what might occur if the
hypothesis is not wrong
• Test their predictions by observations,
experiments, or both
Experiments
 Tests used to support or falsify a prediction
• Variable characteristic is measured and changed
• Dependent variable: is presumably affected by the
independent variable (ex. Severity of hangover)
• Independent variable: controlled by the
experimenter in order to explore its relationship
with the dependent variable (ex. Prophylactic
treatment for a hangover)
• In the control group, variables do not change
A Scientific Approach
Scientific Theory
 A well-tested hypothesis
• Explains a broad range of observations
• Can be used to make useful predictions about
other phenomena
• A good hypothesis has three characteristics:
1. It is reasonably consistent with well-established
facts
2. It is capable of being tested; and test results
should be repeatable by independent observers
3. It is falsifiable (can be proven false)
 Opinion and belief are not scientific theory !!!!
A Falsifiable Hypothesis Can Be
Tested
• A well-stated hypothesis can be tested
• If no evidence is found to support it, the
hypothesis is rejected
• The hypothesis can be shown to be false
• A hypothesis can be supported by data, but it
can’t really be proven true
Some Scientific Theories
Atomic Theory
All Substances consist of
atoms
Big Bang
The universe originated with
an explosion and continues
to expand
Cell Theory
All organisms consist of one
or more cells, the cell is the
basic unit of life, and all
cells arise from existing
cells
Evolution
Change occurs in the
inherited traits of a
population over generations
Global Warming
Human activities are
causing Earth’s average
temperature to increase
1.7 The Power of Experiments
 Biological systems have many variables
 Experiments simplify observations of nature
• Focus on cause, effect, or function of one
variable at a time
 Researchers design experiments to minimize
potential bias in interpreting results
A Controlled Experiment
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.
Experiment
Results
Control Group
Experimental Group
Eats regular
potato chips
Eats Olestra
potato chips
93 of 529 people
get cramps later
(17.6%)
89 of 563 people
get cramps later
(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. 1.11, p. 14
Butterflies and Birds:
A Behavioral Experiment
Wing Spots
Wing Sound
Total
Number of
Butterflies
Number
Eaten
Number
Survived
Spots
Sound
9
0
9 (100%)
No Spots
Sound
10
5
5 (50%)
Spots
No Sound
8
0
8 (100%)
No Spots
No Sound
10
8
2 (20%)
a Wing spots
painted out
b Wing spots
visible; wings
silenced
c Wing spots
painted out;
wings silenced
d Wings painted
but spots visible
e Wings
cut but not
silenced
f Wings painted but
spots visible; wings
cut but not silenced
Stepped Art
Fig. 1-14, p. 18
1.8 Sampling Error in Experiments
 Difference between results derived from testing
an entire group and results derived form testing
a subset of the group.
 Small sample size increases the likelihood of
sampling error in experiments
• In such cases, a subset may be tested that is not
representative of the whole
KEY CONCEPTS:
HOW WE KNOW
 Biologists make systematic observations,
predictions, and tests in the laboratory and field
 They report their results so others may repeat
their work and check their reasoning
Animation: Building blocks of life
CLICK HERE TO PLAY
Animation: Insect development
CLICK HERE TO PLAY
Animation: Life's diversity
CLICK HERE TO PLAY
Animation: Life's levels of organization
CLICK HERE TO PLAY
Animation: One-way energy flow and
materials cycling
CLICK HERE TO PLAY
Animation: Sampling error
CLICK HERE TO PLAY
Animation: Three domains
CLICK HERE TO PLAY