Chapter 1
Introduction to Biology
LESSON 1: UNIFYING PRINCIPLES OF BIOLOGY
Lesson Objectives
 State the four unifying principles of biology as defined
by the College Board.
 Briefly explain how biological life on Earth evolves.
 Explain the purposes of free energy processes and
homeostasis in biological organisms.
 Describe the theories and dogma of biological
information.
 Describe how living things interact and the levels of
structural, biological, and ecological organization in
biological systems.
The “Big Ideas”
 Evolution…evolution drives the diversity and unity of
life
 Free Energy…biological systems utilize free energy and
molecular building blocks to grow, to reproduce, and to
maintain dynamic homeostasis
 Information…living systems store, retrieve, transmit,
and respond to information essential to life processes
 Systems…biological systems interact, and these
systems and their interactions possess complex
properties
http://youtu.be/ibhnP5suqK8 (9:09)
Evolution
Evolution…evolution drives the diversity and unity of life
What is diversity?
 Diversity
 Do all species on Earth live in the same type of habitat
 Do we all reproduce alike
 Do we are physically resemble one another
 Do we all have the exact same resource needs
Evolution drives the diversity of life which insures survival through
variations that develop through genetic mutations that are transferred
between or within populations of species by means of non-random mating,
and immigration and emigration of individuals within and from
populations.
Evolution…continued
What is the unity of life?
 What do we mean by ‘unity of life’?
 universal usage of DNA to store genetic information
 the ribosome technique of protein synthesis
 proteins serve as enzymes and catalysts
 the same 20 amino acids are always used
 a universal genetic code
 DNA triplets coding for same amino acid
 the use of proteins and lipids to make membranes
 the use of the ATP-ADP cycle for chemical energy
Free Energy
Free Energy…biological systems utilize free energy
and molecular building blocks to grow, to reproduce,
and to maintain dynamic homeostasis
Homeostasis
Information
 Information…living systems store, retrieve, transmit, and respond to
information essential to life processes
Systems
 Systems…biological systems interact, and these systems and their
interactions possess complex properties
 Describe how living things interact and the levels of structural,
biological, and ecological organization in biological systems.
Lesson Summary
 Four underlying principles form the basis of biology. They
are evolution, free energy, information, and systems.
 The great diversity of life on Earth today is the result of 4
billion years of evolution. During that time, living things
evolved from simple, single-celled organisms to complex,
multicellular life forms.
 Biological systems utilize free energy & molecular building
blocks to grow, to reproduce and to maintain dynamic
homeostasis.
 Living systems store, retrieve, transmit & respond to
information essential to life processes.
 Many living things interact with one another in some way.
The interactions are often necessary for their survival.
LESSON 2: DISCOVERY OF CELLS AND MICROSCOPES
Lesson Objectives
o
State the cell theory, and list the discoveries that led to
it.
o
Be able to identify the parts of a compound light
microscope.
o
Explain the differences between a SEM (Scanning
Electron Microscope) and a TEM (Transmission Electron
Microscope).
Abiogenesis or Biogenesis?
Recipe for Bees
1.Kill a bull during the first thaw of winter
2.Build a shed.
3.Place the dead bull on branches and herbs
inside the shed.
4.Wait for summer. The decaying body of
the bull will produce bees.
Aristotle…300 B.C. (2300 years ago)
€ Living things follow a set of natural rules different
from nonliving things
€ Special “vital forces” (magical forces in the air)
brought living things into being from nonliving things
€ A hypothesis known as :
spontaneous generation also called abiogenesis
About 350 years ago
Challenges began to arise to the beliefs of
Aristotle
€ How did they challenge these ideas
€ Through experiments and observations to
answer the questions about life…..
€ Do living things come from nonliving
things?????
OBSERVATIONS…
Discovery of Cells
 Cell: smallest unit that can carry out the processes of life;
including transport of materials, obtaining and using energy,
waste disposal, replication, and responding to their
environment.
 If you look at living organisms under a microscope you will
see they are made up of cells; which are the basic unit of all
living things
Anton von Leeuwenhoek
mid 1600s Dutch businessman credited for
creating 1st microscope;
Magnification 200X
Opened up new world
Changed ideas about disease &
sterilization for the next 200
years!!
ANIMALCULES
Robert Hooke
late 1600s (1663)
English physicist; used one of
1st light microscopes.
Coined the term “cell” after
observing cork cells
EXPERIMENTS…
Francesco Redi
Italian Physician
 1668
 Studied maggots
 Did not believe they
came from decaying
meat
 Set up an
experiment
Figure 1-8 Redi’s Experiment on
Spontaneous Generation
Redi’s Experiment
Section 1-2
OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.
HYPOTHESIS: Flies produce maggots.
PROCEDURE
Uncovered jars
Controlled Variables:
jars, type of meat,
location, temperature,
time
Covered jars
Several
days pass
Manipulated Variables:
gauze covering that
keeps flies away from
meat
Responding Variable:
whether maggots
Maggots appear
No maggots appear
appear
CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous
generation of maggots did not occur.
Success???
 Redi thought so, but…
 No air could get into the experimental jars
 There was no “vital force”
 People still believed in spontaneous
generation or abiogenesis
 Back to the drawing board…
Redi’s Second Experiment
Control Group
Experimental Group
Conclusion
 Maggots do not come from dead meat.
 Hypothesis has been supported!
 Does this disprove abiogenesis?
 Only for flies!
The Debate Continued….
 Was Redi right, Aristotle’s ideas had
survived for a millennia, how could they
be WRONG!!!!
 Let’s follow the history of the scientific
investigation and further observations that
finally solved the riddle…
John Needham (British Biologist
& Roman Catholic priest
 Mid-1700’s
 Believed in abiogenesis for microscopic
organisms
Needham’s Experiment
Broth in flask boiled to sterilize it…
Killing microorganisms, then sealed
Microorganisms found growing in flask!!!!
Lazzaro Spallanzani (Italian Scholar)
 1768
 Did not believe in spontaneous generation
 Read about Needham’s work
Samples had not been heated enough
Broth in two flasks boiled to sterilize…
Sealed one immediately after boiling
Left other open
Bacteria found growing only
in open flask
More Observations
1839…
 Schleiden and Schwann made an
important discovery about living things
Beliefs are about to change…..
Matthias
Schleiden
1839
German botanist
“All plants are made
of cells.”
Theodor
Schwann
1839
“All animals are made of cells”
Further concluded all plants and animals
are made of cells
German scientist
More Observations
1839…
 BUT….Schleiden and Schwann did not
understand where cells came from. Was
the belief of the time dating back to the
time of Aristotle (300 B.C.) right? Did cells
come from nonliving matter
(Abiogenesis).
Rudolf virchow
1855
“Where a cell exists,
there must have been
A preexisting cell…”
German physician
Still one more experiment
before true understanding…
Does Abiogenesis happen?
 A contest was devised by the French
Academy of Sciences with a cash award
for the person who could disprove
abiogenesis.
Louis Pasteur
French Scientist
 Mid- 1800s
 Knew he needed to let air in,
but not dust
 Was inspired by…
Swan Necked Flask
 Pour broth into flask
 Heat neck & shape
 Boil broth
 Wait!
Pasteur’s Experiment
Conclusion--1859
 Since no microorganisms could get into
the broth (they were trapped in the curve
of the swan neck), none grew.
 Pasteur broke the neck off a year later,
allowed it to be exposed to air &
microorganisms began to quickly grow.
Biogenesis
 Living things do NOT come from non-living
things. Spontaneous generation does NOT
occur, even with very small organisms.
 Living things only come from other living
things!
Cell Theory
widely accepted explanation of the
relationship between cells and living things
All organisms are made up of one
or more cells.
All the life functions of an
organism occur within cells.
All cells come from preexisting
cells.
Let’s Step Back and Talk About
Microscopes
Magnifying glasses had been in use since
the 1300s
Magnification power of early microscopes
was limited by glass quality used in the
lenses and the amount of light reflected
off the object.
Today we are not limited by light and
mirrors when viewing specimen…
Scanning Electron Microscope
 Runs a pencil-like
beam of electrons
back and forth
across the surface
of a specimen
Creating 3-D Images
Transmission Electron Microscope
Shines a beam of electrons
through a thin specimen.
Creating detailed flat one dimensional
images
http://www.kqed.org/quest/television/the-worlds-most-powerful-microscope
Unfortunately, in class we only have
compound light microscopes
Parts of the microscope review…
Lesson Summary
 Discoveries about cells using the microscope
and experimental observations led to the
development of the cell theory. This theory
states:
 All organisms are made of one or more cells
 All the life functions of organisms occur within
cells
 All cells come from already existing cells.
 Electron microscopes can produce highly
magnified one dimensional and 3-D image of
specimens.
LESSON 3: THE NATURE OF SCIENCE
Lesson Objectives
o
Identify the goal of science.
o
Describe how scientists study the natural world; using
the scientific method.
o
Explain how and why scientists do experiments.
o
Describe types of scientific investigations.
o
Explain what a scientific theory is.
The Goal of Science
 Science is a distinctive way of gaining knowledge about
the natural world that starts with a question and then
tries to answer the question with evidence and logic.
 The goal of science is to understand the natural world.
To achieve this goal, scientists make certain
assumptions. They assume that:
 Nature can be understood through systematic study.
 Scientific ideas are open to revision.
 Sound scientific ideas withstand the test of time.
 Science cannot provide answers to all questions.
Nature Can Be Understood
 Though scientific laws. Scientific laws are statements
that describe what always happens under certain
conditions in nature.
 LAW OF GRAVITY
Scientific Ideas Can Change
 Knowledge is a process
 New observations are made
 Ideas are retested
 Testing leads to challenges and possible revisions of
ideas
 Thus scientists gradually build an increasingly accurate
and detailed understanding of the natural world.
Scientific Knowledge Can
Withstand the Test of Time
 Scientific knowledge that have been tested repeatedly and found to
be true are considered scientific theory.
 By true we mean they are supported by a great deal of scientific
evidence.
 Scientific theories are distinguished from philosophical theories in
that each of their theorems are statements about observable data,
whereas a philosophical theory includes theorems which are ideas or
principles.
 Biological Scientific Laws and Theories you should know:
 Theory of Evolution by Natural Selection
 Cell Theory
 Law of Biogenesis
 Laws of Thermodynamics
Science Cannot Answer All Questions
 Scientific knowledge is based on evidence and logic, derived
from questioning and the testing of things observed.
 An observation is anything that is detected either through human
senses or with instruments and measuring devices that extend
human senses.
 Things that cannot be observed or measured by current means—such
as supernatural beings or events—are outside the bounds of science.
 Consider these two questions about life on Earth:
 Did life on Earth evolve over time?
 Was life on Earth created through another method?
The first question can be answered by science on the basis of
scientific evidence and logic. The second question could be a matter
of belief. Therefore, it is outside the realm of science.
The Scientific Method
 Basic method for gaining scientific knowledge, used by
all areas of science and is conducted through scientific
investigations.
Let’s say you communicate your
results, numerous others retest
your hypothesis and it is consistently
supported. What could it become?
Experiments
 An experiment is a special type of scientific investigation that is
performed under controlled conditions, usually in a laboratory.
 Variables:
 An experiment generally tests how one variable is affected by another.
 The affected variable is called the dependent variable.
 The variable that affects the dependent variable is called the independent
variable.
 Sample size and repetition:
 Sample is the individuals or events that are studied.
 Size is usually much smaller than all such individuals or events that exist
in the world.
 The larger the sample is, the more likely the results are generally true.
 Repetition, the more times that an experiment is repeated and the same
results obtained, the more likely the results are valid.
Types of Data Collected During
Experiments…
Observations and Inferences
 When you observe, you use one or more of your senses
to perceive objects and events. You might see
movement of a water flea, hear the cry of an osprey, or
touch the skin of a salamander. It is critical for
observers to describe exactly what they perceive and not
what they think is happening (inference).
Lesson Summary
 The goal of science is to understand the natural world through
systematic study. Scientific knowledge is based on evidence and
logic.
 Scientists gain knowledge through scientific investigations. A
scientific investigation is a plan for asking questions and testing
possible answers.
 Scientists use experiments to test hypotheses under controlled
conditions. Experiments are often done in a lab.
 Other types of scientific investigations include natural studies and
modeling. They can be used when experiments are difficult to do.
 Scientific theories are broad explanations that are widely accepted
as true. This is because they are supported by a great deal of
evidence.
The Three Little Pigs