Transcript Bio 204 Introduction to Evolution, Ecology, and Biodiversity

Bio 204
Introduction to Evolution,
Ecology, and Biodiversity
Alejandro Acevedo
Janice Lapsansky
Winter 2005
Biology: The Science of Life
 Why do we study life?
 How do we study life?
…
a matter of scale - - size and time
 Which ideas/concepts guide biologists?
Organizing the Diversity of Life

Taxonomy
= the process of naming and classifying
organisms
 Three Domains:
Bacteria
Archaea
Eukarya

Five Kingdoms: (see figure on next slide)
Themes in the Study of Life
 Levels of organization:
 The
difference between living and nonliving is one of degree, not kind.
What does this mean?
 Cells
are an organism’s basic unit of
structure and function
What is a cell?
List one example that illustrates the
interdependence of structure and function.
Fig. 1.4
What are some of the main differences between prokaryotic
and eukaryotic cells?
Fig. 1.2 Levels of
Organization
Themes in the Study of Life
 Emergent Properties

Each level of biological organization has
emergent properties that result from the
interaction of structural and functional components

These emergent properties include those
characteristics we often use to describe life:
metabolism, growth and development,
homeostasis, reproduction, and evolutionary
adaptation.
Respond to the following statement:
“Living things are chemical and physical machines.”
Is your current view more in line with holism or reductionism?
Themes in the Study of Life
 Homeostasis
= the maintenance of a dynamic equilibrium
Why does an organism’s internal environment
change?
Why is a stable internal environment important to an
organism’s survival? Describe an example.
 Most
homeostatic mechanisms operate as
negative feedback loops.
Draw the components of a basic negative feedback
loop.
Themes in the Study of Life
 Informational Molecules

Some biological macromolecules contain “code”
by virtue of the sequence of the building blocks
they contain.
Name the type of molecule that contains the instructions for
maintaining the structure and function of an organism.
Name the type of molecule that is made from these
instructions.
 All forms of life use this same code
Are there other similarities that unify the diversity of life?

Inheritance of traits relies on accurate duplication
and transmission of this code to offspring
Can organisms change because they “have to” in order to
survive in a challenging environment?
Themes in the Study of Life
 All living things depend directly or
indirectly on all other living things for
survival
Briefly describe how an
organism changes its
biotic environment….its
abiotic environment.
Describe the flow of
energy and raw
materials through the
biosphere.
Themes in the Study of Life

Evolution is the core theme of biology
“descent with modification”
 Natural selection is one mechanism of
evolution

Q: Which of the following observations made by Charles
Darwin was/were pivotal to the development of his
concept of evolution
a.
b.
c.
d.
Populations never produce more offspring than can be
supported by the environment
Individuals in a population exhibit at least slight differences
in their structure and/or function
Some individuals possess traits that make them more “fit”
in their environment
Human skin cells look exactly like bacterial cells from
mineral hot springs
Help Jane with her
homework…
True or False.
Natural selection creates
adaptations.
Justify your answer.
Themes in the Study of Life
 Scientific Process
 …begins
with a question
 one way to acquire knowledge
Can any question be answered by
the scientific method?
2 basic ways to approach a question:
 inductive
reasoning
 deductive reasoning
Themes in the Study of Life
Inductive Reasoning:

generalize from specific observations
example:
When is inductive reasoning used in the
scientific process?
Deductive Reasoning:

propose a model (involving assumptions)
that provides a tentative explanation that
can be applied to specific situations
requires that evidence be collected to test
the model and assumptions
?
Hypothesis
Test
modify or abandon
repeat
Reject
Support
•What important skills are critical to your ability to formulate
hypotheses?
•When is more than one hypothesis appropriate in science?
•What is a scientific theory and how is it different from a hypothesis?
Small Group Exercise:
An Introduction to Correlation
Does smoking cause lung cancer? Does drunk driving cause
accidents? Do thin people live longer? You may think you
know the answers to some or all of these questions already. On
what evidence and/or reasoning to you base your answers?
The collection and analysis of data to determine whether two
variables are “linked” are important elements in scientific
investigations. Finding variables to be linked (i.e. correlated)
suggests the possibility of a cause-and-effect relationship.
The purpose of this small group exercise is to evaluate
information based on the results of scientific research, reported
in a newspaper article. Read the article and answer the
questions that follow.
Doing poorly: Study links low
income with high blood pressure
1. What two variables are correlated
according to the article?
2. Is this a direct or inverse correlation?
Explain.
3. Does either the author or researcher
argue that one of the variables is the
cause? Explain