Discover Biology
FIFTH EDITION
CHAPTER 1
The Nature of Science and the
Characteristics of Life
Anu Singh-Cundy • Michael L. Cain
© 2012 W. W. Norton & Company, Inc.
Earthbound Extraterrestrial?
Or Microbe in the Mud?
• Bacterium discovered that uses arsenic
instead of phosphorus in its DNA
• All life created from set recipe of chemical
building blocks?
Not!
Your assignment for next
Wed is to read about this.
Researches Wrangle over
Bacteria
• Previously, scientists agreed that all life on Earth
required six major elements:
–
–
–
–
–
–
Carbon
Hydrogen
Nitrogen
Oxygen
Sulfur
Phosphorus
• The bacteria that does not require phosphorus raises the
question of whether any of the six major elements of life
are actually required!
Science Is a Body of Knowledge and
a Process for Generating That
Knowledge
• The process is called the scientific method
It can be applied to all areas of science
• It begins with observation
• Diet Beverages and depression (March 2013)
After observation comes
The Hypothesis
“deductive reasoning”
Diet Beverages and depression
If…..
Then……..
controls
• What is the purpose of a control
group?
2 ways we use the word control in science
• Erbitux ($17,000 month!)
2 ways we use the word control in science
WE CONTROL FOR
Variables
• What are variables? How many do we
change at a time? (How do we “control”
them?)
Does sample size matter?
U.S.
315,151,548 ~9 million depressed
World 7,059,238,065 ~350 million depressed
• What is sampling error?
BLIND studies
DOUBLE BLIND studies
RESULTS
When making a graph - what goes on x
axis and what goes on y axis?
DEPENDENT
VARIABLE
Effect
(“then” this)
GRAPH
WHAT VARIES
BASED ON
WHAT YOU DID
(DEPENDS)
INDEPENDENT VARIABLE
Cause (“if” this)
WHAT YOU VARY OR
CHANGE IN EXPERIMENT
Then you will test
higher for depression
WHAT VARIES
BASED ON
WHAT YOU DID
(DEPENDS)
MOST HUMAN STUDIES ARE
COORELATIONS
GRAPH
If you drink diet drinks
WHAT YOU VARY OR
CHANGE IN EXPERIMENT
What can COORELATIONS really tell us?
Are there too many
variables in human studies?
Proved? Not Proved?
Right? Wrong?
SUPPORTED
NOT SUPPORTED
What is a theory??
• A SCIENTIFIC theory is:
– a proposed explanation for a natural phenomenon.
– the body of interconnected concepts, supported by
scientific reasoning and experimental evidence
• solid ground of science
Evolution is the core of biology
• Species descend with modification
• Natural selection
(Darwin published first)
CHANGE OVER TIME
• does
NOT
mean we descended from
apes!!!!
• does mean things
change over
time
life has been
shaped by evolution
Figure 1.9 Natural selection
Large ground finch (seeds)
Vegetarian finch (buds)
Cactus ground finch
(cactus fruits and flowers)
Woodpecker finch (insects)
Concept Quiz
Observation: After a lengthy rainstorm, earthworms are
on the surface of a sidewalk.
Which of the following is an adequate hypothesis for
the observation?
a) The sidewalk is hard and flat.
b) Lightning attracts earthworms.
c) Saturated soil makes it difficult for the earthworms
to “breathe” so they come out of the ground.
How to study:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Read before class
Ask yourself questions about the headings
Read first sentence of each paragraph
Preview figures
Now read – and take notes (read out loud)
Read again after 3-4 days
Know key terms
Use study aids
Use other books
10.Take breaks
11.SLEEP
What is common to LIFE?
CELLULAR LEVEL
Atoms
•cells
Molecule
Macromolecule
Organelle
Cell
Cells!
• More than 10
trillion cells in
human body
Properties of life
•
•
•
•
One or more cells
Reproduction
Energy utilization
Response to
environment
• homeostasis
• evolutionary
adaptation (DNA
information base)
Emergent properties
•Hierarchy (Figure 1.2)
- molecule
– organelle
– cell
– tissue
– organ
– organism
Is the whole greater than
its parts?
Novel properties emerge
Problem Reductionism –)
Life depends on chemical and
molecular reactions
we must understand atoms and molecules
ATOMS
MOLECULES
•ORGANIZATION OF LIFE Hierarchy
-atoms
- molecules
Tissue
Organ
• organelles (little organs)
–
–
–
–
–
–
–
–
–
cells
Tissue
organ
organism
species
population
community
ecosystem
bioosphere
Organ
system
Organism
Organisms are open systems that
interact with the environment
• Ecosystems
– cycling of nutrients
– flow of energy
– produce and consume
• GENES INTERACT
WITH ENVIRONMENT
PKU
•Energy conversion
–plants solar energy to chemical energy
Regulation
• Homeostasis
• Feedback
• negative - temperature
• positive – blood clots
Cells are the basic unit of
structure and function
• Cell theory
– living things are made of cells
– cells come from other cells
• all cells have membranes
• all cells have DNA (at some stage)
Microscopes
• Hooke (1665)
• Leeuwenhoek
(1675)
Diversity!
• Estimates - 10 million - 200 million
species!!!!
– Currently 1.8 million species.
• 280,000 plants
• 50,000 vertebrates
• 750,000 insects
– Thousands more each year
Continuity is heritable- based on
DNA
• Order requires
instruction
– four building blocks
nucleotides
– sequence - same to all life
example: eyes
Huntington's disease (CAG
repeats)
Structure is related to function
Function is related to structure
Human
Human
Cat
Bat
Porpoise
Horse
which comes first?
Science, technology and society
are interdependent
• Example – scientific discovery needs tax dollars
•
•
•
•
educate
politicians
bureaucrats
corporate leaders
voters
Neuroscience in USA (Both Watson and Crick
moved here)
POLITICS
• APPLIED SCIENCE
• BASIC SCIENCE
Concept Quiz
Which of the following is a
characteristic shared by all living
organisms?
A. Movement
B. Reproduction
C. Breathing
Concept Quiz
Which organism is the producer?
A. Cactus
B. Rattlesnake
C. Hawk
© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e