Download Chapter #1 - eLearning

Introduction: Themes in the
Study of Life
Chapter 1 - AP Biology
Biology
• The Study of Life
• Unifying Themes
–
–
–
–
–
–
–
–
–
–
–
Order
Emergent Properties
The Cell
Heritable Information
Structure relates to Function
Interaction with the
Environment
Regulation
Unity and Diversity
Evolution
Scientific Inquiry
Science, Technology and
Society
LIFE’S HIERARCHICAL ORDER
• One of life’s most distinctive features is it’s
ORDER.
• Because life is ORDERED, it can be studied in
terms of a structural hierarchy.
• Hierarchy of structural levels
– Each structural level builds on the levels below it.
– Emergent properties – special qualities that result from
the structure at each level.
Hierarchy of Structural Levels
•
•
•
•
•
•
•
•
•
•
•
Atoms
Molecules
Organelles
Cells
Tissues
Organs
Organ systems
Organisms
Population
Community
Ecosystem
Atoms
• The chemical building blocks of all matter
• The lowest, most basic level of the
structural hierarchy
Molecules
• Composed of two or
more atoms
• Atoms become
organized into the
many complex
biological molecules
(like proteins,
carbohydrates, etc.)
that make up living
things
Organelles
• The components of
cells
• Made up of many
complex biological
molecules
Cells
• The subunits of all
organisms
• Fundamental units of life
• An organism’s basic units
of structure and function
• The lowest level of
structure that is capable
of performing ALL the
activities of life.
• ALL organisms are
composed of cells.
Tissues
• Groups of cells similar
in structure that are
doing a common
function
Organs
• Groups of different
tissues working
toward a common
function
Organ
Systems
• Groups of
different
organs
working toward
a common
function
Organisms
• The units of life
• May be single celled (Amoeba) OR
multicelluar with a division of labor
among different cells
• Multicellular organisms exhibit 3 major
structural levels above the cell.
– Tissues
– Organs
– Organ Systems
• So, just keep in mind that an organism
may be UNICELLULAR and may NOT
necessarily have tissues, organs, organ
systems.
Population
• Localized group of organisms belonging to
the same species
Community
• Populations of different species living in the
same area
Ecosystem
• Community
interactions that
include nonliving
(Abiotic) features
of the
environment (like
soil and water)
Emergent Properties
• Properties that result (emerge) from the
interactions between components within a level of
the structural hierarchy.
• KEY: The Whole is greater than the sum of its
parts. The ARRANGEMENT and
INTERACTIONS of molecules (or organelles, or
cells, or tissues, etc.) are integral in causing the
unique properties of life at each level of the
hierarchy.
Emergent Properties
Examples
– A molecule like a protein has properties that
are not exhibited by any of its component
atoms.
– The human brain, if disrupted by a head injury,
may cease to function, even if all its “parts” are
still present.
Scientists and the History of the
Cell
• Since cells are the fundamental units of life,
this section will focus on their discovery
and some of the scientists who
– First observed them, AND
– Realized their significance
Robert Hooke
• English Scientist
• First to describe and
name cells – 1665
• Observed cork (oak bark)
magnified 30x
• Hooke never realized the
significance of his
discovery
• For more on Robert
Hooke, click HERE.
Anton van Leeuwenhoek
• Dutch; working at the
same time as Hooke.
• Discovered organisms we
now know to be singlecelled. He observed:
– Microbial world in a drop of
pond water
– Blood cells
– Sperm
• Developed magnifying
glasses that magnified up
to 300x
Anton van Leeuwenhoek
• Views to the right
show
– Top: A microscope like
van Leeuwenhoek’s
– Bottom: What he
would have seen
through such a
microscope – these are
bacteria
– For more on van
Leeuwenhoek, click
HERE.
Schleiden and Schwann
• 1839
• German biologists
• Acknowledged cells as
the fundamental units of
life
• Summarized their own
microscopic studies and
those of others by
concluding that all living
things consist of cells
• Formed the basis of the
CELL THEORY
• Schwann is on the left,
Schleiden on the right.
Cell Theory
• Cell Theory began with the summative
ideas of Schleiden and Schwann;
1: All living things are made of cells
2: All cells come from other cells
2 Major Cell Types
Prokaryotic cells
– No nucleus
– No membrane
bound organelles
– Tough cell walls
– ALL bacteria
Eukaryotic Cells
Eukaryotic cells
– Have a Nucleus
– DNA in chromosomes
– Membrane bound
organelles
– May or may not have
cell walls
– Everything EXCEPT
bacteria
Inheritable Information
• All life is connected by
a common genetic
code
• DNA, RNA
STRUCTURE RELATES TO
FUNCTION!
• Anatomy/shape of structures nearly always
relates to how they work.
Examples of Form Fitting
Function:
• Aerodynamically
efficient shape of a
bird’s wing
Examples of Form Fitting
Function:
• Skeleton of the bird is
strong but light to aid
in flight.
Examples of Form Fitting
Function:
• Flight muscles (indeed
all muscles) are
controlled by neurons
• Neurons transmit
impulses
• Neuron structure is
especially well suited
for communication like
this
Examples of Form Fitting
Function:
• Muscle cells need
enormous amounts of
energy, which they obtain
from organelles called
mitochondria
• Mitochondria consist of
highly folded membranes
which allow lots of energy
to be made in a small
space.
Organisms Continuously
Interact with their Environments
• Organisms interact with
each other AND nonliving
components of their
environment
– Photosynthesis
– Cell Respiration
– Nutrient Cycling
• Energy Flow through the
environment
• Transformation of energy
from one form to another
• Solar energy to chemical
energy
• Chemical energy to
mechanical energy
Living Things Must Maintain
Balance – Regulatory Systems
• Homeostasis
• Maintenance of homeostasis is achieved by using
regulatory systems
– Chemical reactions are regulated by the use of
enzymes
– Feedback mechanisms
• Allow for the self-regulation of biological processes
• Product of a process regulates the process
• Positive feedback
– Speeds up a process
• Negative feedback
– Slows or stops a process
Example
of
Positive
Feedback
Loop
Example of Negative
Feedback Loop
Unity and Diversity
• Diversity
– 1.5 million species
identified
– Estimates of total
diversity range from 5
million to over 100
million species
Unity and Diversity
• Unity
– Universal genetic code
– Similarities in cell
structure, etc.
– The diagram at right
shows the fundamental
similarity between ALL
eukaryotic flagella,
whether on a
paramecium or in the
human windpipe.
Organizing the Diversity of Life
• Taxonomy – science
that names and
classifies species
• We have a 6 kingdom
system
3 Domains of Life
6 Kingdoms of Life
Evolution is the Core Theme of
Biology
• All of Life is Connected
– Remember diversity AND UNITY
• Evolution is the process that has
transformed life from its earliest beginnings
to the vast diversity of today.
Charles Darwin
• 1859, published Origin
of Species
• For lots more
information about
Charles Darwin, Click
HERE.
• The photo is of Darwin
with his son, William in
1842.
Origin of Species
• Darwin’s book presented two themes:
– “descent with modification.”
– Darwin’s theory of HOW life evolves – the mechanism
called, Natural Selection.
• Darwin developed his ideas by putting together
pieces of the puzzle that were already known at
the time – he, however, was the only one to put
them all together.
Darwin’s Observations
• Individuals are varied
• Individuals produce more offspring than the
environment can support, thus leading to
competition
“Survival of the Fittest”
• Some organisms will be
better suited for this
competition than others
• Those best suited to
compete in their
environment will have
greater reproductive
success than those not as
well suited
• They will be better
represented in the next
generation and so on.
• This is Natural Selection
Natural Selection and Evolution
• Darwin proposed that natural selection
could produce new species from ancestral
species
– Cumulative effects of many small adaptations
adding up from one generation to the next
– Over the span of many years.
• Descent with Modification (evolution)
accounts for both the unity and diversity of
life.
Science as Process
• Science is simply a way of knowing.
– Remember, it is not the only way of knowing.
• It seeks to answer questions about the natural
world
• Science operates under the premise that
questions about the natural world are answerable
by making observations of the natural world and
that the events observable in nature can be
explained in terms of natural laws.
Pseudoscience
• The supernatural is
BEYOND the realm of
scientific discussion
because the supernatural
is not bound by the laws
of the natural world.
– Science has no means
of studying something
that is not bound by the
laws of nature.
Scientific Method
• Outlines a series of steps for answering
questions about the natural world
• Scientists do not adhere strictly to this
method in a step-wise fashion, but it is
used by all scientists in some form.
• Indeed, all of us use some form of this
method each day to solve problems.
The Importance of a Testable
Hypothesis
• Hypothesis – a tentative answer to some
question
• Having a TESTABLE hypothesis is critical
to carrying out the scientific method.
• Having a hypothesis that is actually
testable by the scientific method LIMITS
the kinds of questions the scientific method
can answer.
Other Important Points
Regarding Hypotheses
• Hypotheses are possible explanations for some phenomenon.
– Never just a statement or observation. Must seek to explain WHY
something is happening.
• Hypotheses reflect past experience
– In other words, hypotheses should seem reasonable…at least this is
where hypotheses should start.
• Multiple hypotheses should be proposed whenever possible
– This helps a scientist avoid “favoring” a particular outcome in an
experiment.
• Again, Hypotheses should be TESTABLE.
• Hypotheses can be eliminated but NOT confirmed or “proven” with
absolute certainty.
– Even the most thoroughly tested hypotheses are accepted only
conditionally , pending further investigation.
Controlled Experiments
• Subjects are divided into two groups
– Experimental (group with variable changed)
– Control (group without variable)
• The two groups should be treated exactly alike
EXCEPT for the ONE variable the experiment is
designed to test
• This provides a basis for comparison
A Critical Problem in Today’s
Science
• Be aware that science, like any other type of
information can be politicized by different groups
seeking certain political/commercial outcomes.
• It is VERY difficult for even an educated person to
tell the difference between “bad” science and
“good” science.
– Bad science – experiments designed to
support a desired result
– Good science – experiments designed to
determine the answer to some question.
Questions?
• Please feel free to ask any questions
now.
• At the end of each page of notes- please
add 3-4 sentences (summary) of that
page. Please add in your left column
questions, notes and clarification.