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SCIENTIFIC INQUIRY
Lifelines: Darwin and the
Theory of Inheritance
Teacher’s Guide
31374
A DIVISION OF
FILMS MEDIA GROUP
INTRODUCTION
This Teacher’s Guide provides information to help you get the most out of Lifelines: Darwin and the Theory of
Inheritance. The contents in this guide will allow you to prepare your students before using the program and
present follow-up activities to reinforce the program’s key learning points.
In this program, experts discuss three key scientists and their contributions to the understanding of evolutionary
genetics: Charles Darwin and his theory of natural selection; Gregor Mendel and his breeding experiments;
and Friedrich Miescher, who discovered DNA. The results of their work combine natural science, botany, and
chemistry to form a comprehensive explanation of how species evolve.
LEARNING OBJECTIVES
After viewing the program, students will be able to:
● Discuss Charles Darwin’s theory of natural selection.
● Explain the dilemma Darwin experienced with his theory of inheritance.
● Understand how Gregor Mendel’s experiments led to the discovery of the laws of inheritance.
● Understand how Friedrich Miescher’s discovery of the molecule DNA advanced the theory of evolution and
inheritance.
● Describe the role of DNA.
● Explain how Darwin, Mendel, and Meischer’s theories and research are interrelated.
EDUCATIONAL STANDARDS
National Standards
This program correlates with the National Science Education Standards from the National Academy of Sciences
and the Project 2061 Benchmarks for Science Literacy by the American Association for the Advancement of
Science. The content has been aligned with the following educational standards and benchmarks from these
organizations.
● Understand behavior of organisms.
● Understand diversity and adaptations of organisms.
● Understand matter, energy, and organization in living systems.
● Understand populations and ecosystems.
● Understand interdependence of organisms.
● Understand regulation and behavior.
● Understand biological evolution.
● Understand reproduction and heredity.
● Understand molecular basis of heredity.
● Understand structure and function in living systems.
● Understandings about scientific inquiry.
● Abilities necessary to do scientific inquiry.
● Understand science and technology in society.
● Understand natural resources.
● Understand populations, resources, and environments.
● Understand population growth.
● Understand form and function.
● Understand evolution and equilibrium.
● Understand evidence, models, and explanation.
● Understand systems, order, and organization.
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● Understand that the scientific problem that led to the theory of natural selection was how to explain similarities within the great diversity of existing and fossil organisms.
● Understand that prior to Charles Darwin, the most widespread belief was that all known species were created
at the same time and remained unchanged throughout history. Some scientists at the time believed that
features an individual acquired during its lifetime could be passed on to its offspring, and the species could
thereby gradually change to fit its environment better.
● Understand that Darwin argued that only biologically inherited characteristics could be passed on to offspring.
Some of these characteristics were advantageous in surviving and reproducing. The offspring would also
inherit and pass on those advantages, and over generations the aggregation of these inherited advantages
would lead to a new species.
● Understand that the quick success of Darwin’s book On The Origin of Species, published in the mid-1800s,
came from the clear and understandable argument it made, including the comparison of natural selection to
the selective breeding of animals in wide use at the time, and from the massive array of biological and fossil
evidence it assembled to support the argument.
● Understand that after the publication of On The Origin of Species, biological evolution was supported by the
rediscovery of the genetics experiments of an Austrian monk, Gregor Mendel, by the identification of genes
and how they are sorted in reproduction, and by the discovery that the genetic code found in DNA is the same
for almost all organisms.
● Understand that by the 20th century, most scientists had accepted Darwin’s basic idea. Today that still holds
true, although differences exist concerning the details of the process and how rapidly evolution of species
takes place. People usually do not reject evolution for scientific reasons but because they dislike its implications, such as the relation of human beings to other animals, or because they prefer a biblical account of
creation.
● Understand that in formulating and presenting his theory of biological evolution, Charles Darwin adopted
Lyell’s belief about the age of the earth and his style of buttressing his argument with vast amounts of
evidence.
● Understand that reproduction is necessary for the survival of any species. Sexual behavior depends strongly
on cultural, personal, and biological factors.
● Understand that new ideas in science sometimes spring from unexpected findings, and they usually lead to
new investigations.
● Understand that there are different traditions in science about what is investigated and how, but they all have
in common certain basic beliefs about the value of evidence, logic, and good arguments. And there is agreement that progress in all fields of science depends on intelligence, hard work, imagination, and even chance.
● Understand that in the short run, new ideas that do not mesh well with mainstream ideas in science often
encounter vigorous criticism. In the long run, theories are judged by how they fit with other theories, the
range of observations they explain, how well they explain observations, and how effective they are in predicting new findings.
● Understand that new ideas in science are limited by the context in which they are conceived; are often rejected by the scientific establishment; sometimes spring from unexpected findings; and usually grow slowly,
through contributions from many investigators.
● Understand that when similar investigations give different results, the scientific challenge is to judge whether
the differences are trivial or significant, and it often takes further studies to decide. Even with similar results,
scientists may wait until an investigation has been repeated many times before accepting the results as
correct.
● Understand that scientific knowledge is subject to modification as new information challenges prevailing
theories and as a new theory leads to looking at old observations in a new way.
● Understand that from time to time, major shifts occur in the scientific view of how the world works. More
often, however, the changes that take place in the body of scientific knowledge are small modifications of
prior knowledge. Change and continuity are persistent features of science.
● Understand that some scientific knowledge is very old and yet is still applicable today.
● Understand that no matter how well one theory fits observations, a new theory might fit them just as well or
better, or might fit a wider range of observations. In science, the testing, revising, and occasional discarding of
theories, new and old, never ends. This ongoing process leads to an increasingly better understanding of how
things work in the world but not to absolute truth. Evidence for the value of this approach is given by the
improving ability of scientists to offer reliable explanations and make accurate predictions.
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● Understand that important contributions to the advancement of science, mathematics, and technology have
been made by different kinds of people, in different cultures, at different times.
● Understand that progress in science and invention depends heavily on what else is happening in society, and
history often depends on scientific and technological developments.
Reprinted with permission from National Science Education Standards © 1999 by the National Academy of Sciences, courtesy of the National
Academies Press, Washington, D.C.
From BENCHMARKS FOR SCIENCE LITERACY by the American Association for the Advancement of Science, copyright 1993 by the American
Association for the Advancement of Science. Used by permission of Oxford University Press, Inc. Please note: judgments about the alignment
of content presented here with the learning goals in BENCHMARKS FOR SCIENCE LITERACY are those of the author and do not represent the
opinion or endorsement of the AAAS or Oxford University Press, Inc.
English Language Arts Standards
The activities in this Teacher’s Guide were created in compliance with the following National Standards for the
English Language Arts from the National Council of Teachers of English.
● Use spoken, written, and visual language to accomplish their own purposes.
● Adjust their use of spoken, written, and visual language (e.g., conventions, style, vocabulary) to communicate
effectively with a variety of audiences and for different purposes.
● Use a variety of technological and information resources (e.g., libraries, databases, computer networks, video)
to gather and synthesize information and to create and communicate knowledge.
● Conduct research on issues and interests by generating ideas and questions, and by posing problems. They
gather, evaluate, and synthesize data from a variety of sources (e.g., print and nonprint texts, artifacts, people)
to communicate their discoveries.
● Employ a wide range of strategies as they write and use different writing process elements appropriately to
communicate with different audiences for a variety of purposes.
Standards for the English Language Arts, by the International Reading Association and the National Council of Teachers of English, copyright
1996 by the International Reading Association and the National Council of Teachers of English. Reprinted with permission.
Technology Standards
The activities in this Teacher’s Guide were created in compliance with the following National Education
Technology Standards from the National Education Technology Standards Project.
● Demonstrate a sound understanding of the nature and operation of technology systems.
● Practice responsible use of technology systems, information, and software.
● Develop positive attitudes toward technology uses that support lifelong learning, collaboration, personal
pursuits, and productivity.
● Use technology resources for solving problems and making informed decisions.
● Use technology tools to process data and report results.
● Use technology to locate, evaluate, and collect information from a variety of sources.
● Evaluate and select new information resources and technological innovations based on the appropriateness
for specific tasks.
● Use technology tools to enhance learning, increase productivity, and promote creativity.
The ISTE National Education Technology Standards Project standards are reprinted with permission.
PROGRAM OVERVIEW
This program discusses the contributions of Charles Darwin, Gregor Mendel, and Friedrich Miescher. Their
individual achievements in the area of evolutionary genetics are presented. How their results combined to form
a complete theory of how species develop is explained.
MAIN TOPICS
Topic 1: Darwin’s Theory of Natural Selection
The first section discusses Darwin’s theory of evolution through natural selection and his ideas regarding
inheritance found in his popular book, On The Origin of Species. The brilliance of his ideas as well as the contradictions and inaccuracies are presented.
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Topic 2: Gregor Mendel’s Great Discovery
This section focuses on Mendel’s experiments with crossing varieties of plants, in particular the pea plant. His
contribution to the field of genetics through his discovery of dominant and recessive characteristics is described.
Mendel’s crucial theory of how an individual’s characteristics are passed down through generations is of
particular interest.
Topic 3: Friedrich Miescher and DNA
This section reflects the work of Miescher and his discovery of DNA while working with white blood cells taken
from bandages. The importance of this discovery in explaining how characteristics are physically passed down
through generations is described.
Topic 4: The New Synthesis
The relationships and complimentary nature of the work of these three scientists is the focus of this segment.
Clarification is provided on how Mendelian genetics provides the basis for Darwin’s theory of evolutionary
change and how, together with the discovery of DNA, by Miescher, they form the foundation for our view of
modern biology
Topic 5: Researchers Today
The final section begins with a look at how DNA can be extracted from tissue. The work of Watson and Crick
transformed the abstract idea of DNA into a three dimensional structure. The ways in which researchers continue
to work today with DNA is also discussed here.
FAST FACTS
● Charles Darwin believed all living things evolved over millions of years through a process called natural
selection.
● Natural selection is nature’s way of choosing the varieties of species best adapted to survive and reproduce.
● Darwin’s visit to the Galapagos Islands, in the eastern Pacific Ocean, was especially important to the development of his theories on natural selection. It was there that he began to understand what causes plants and
animals to evolve.
● Charles Darwin almost didn’t make it on the famous voyage of the Beagle to the Galapagos Islands, which
provided the backdrop and foundation for his famous book, On The Origin of Species. The reason? The captain
of the ship thought Darwin’s nose “indicated a lack of energy.”
● Gregor Mendel was an Austrian monk whose experiments on inheritance in pea plants led to a greater
understanding of heredity and inheritance. He discovered three important laws: 1) The Law of Segregation;
2) The Law of Dominance; and 3) The Law of Independent Assortment.
● Mendel’s Law of Segregation includes the following points: 1) Alternative versions of genes account for
variations in inherited characteristics; 2) For each characteristic, an organism inherits 2 genes, one from
each parent; and 3) If the two alleles differ, then the dominant allele is fully expressed in the organism’s
appearance, and the other allele is the segregate during gamete production.
● Mendel uncovered a critical aspect of inheritance. It was the idea that somehow individual characteristics are
passed on through the generations, sometimes showing themselves in a particular individual and sometimes
not showing themselves for several generations to come.
● There is a two-stage mechanism for classification in biology. First, an organism is placed in a large group
called a genus. It is then categorized into a smaller group called a species.
● A chemist named Friedrich Miescher was the first to identify what we know as DNA. He was also the first
to speculate that these molecules had something to do with how inheritance is handed down through
generations.
● DNA and proteins are the key molecules of a cell’s nucleus.
● The double-helix structure of DNA was discovered in 1953 by James Watson and Francis Crick. The length of a
single human DNA molecule, when extended, is 1.7 meters (5 feet, 6 inches).
● Although she is not typically recognized, Watson and Crick built upon the work of a woman scientist, Rosalind
Franklin, whose work was a key part of the discovery of the structure of DNA.
VOCABULARY TERMS
allele: Any of several forms of a gene, usually arising through mutation, which are responsible for hereditary
variation.
biology: A science that deals with living things and life processes.
chromosome: Threadlike body, consisting of chromatin, which is found in a cell nucleus; carries genes in a
linear order.
DNA: Any of the class of nucleic acids that contains deoxyribose, found chiefly in the nucleus of cells; functions
in the transference of genetic characteristics and in the synthesis of protein.
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dominant: One of a pair of alternate alleles which masks the effect of the other when both are present in the
same cell or organism.
evolution: The continuous genetic adaptation of organisms or species to the environment by the integrating
agencies of selection, inbreeding, mutation, and hybridization.
gene: The unit of the chromosome that controls the development of hereditary characteristics.
generation: A body of living beings constituting a single step in the line of descent from an ancestor.
hereditary: Genetically passed from parent to offspring.
inheritance: The genetic characteristics transmitted from parent to offspring, taken collectively.
mutation: A sudden departure from the parent type, as when an individual differs from its parents in one or
more heritable characteristics, caused by an alteration in a gene or chromosome.
recessive: One of a pair of alternative alleles, the effect of which is masked by the activity of the second when
both are present in the same cell or organism.
species: The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, able to breed among themselves, but are not
able to breed with members of another species.
theory: A plausible or scientifically acceptable general principle offered to explain observed facts.
variation: A deviation in the structure or the character of an organism from that of others of the same species
or group, or from that of the parents.
PRE-PROGRAM DISCUSSION QUESTIONS
● How have humans adapted to their environment through time?
● In what ways has life on Earth changed through the centuries?
● What traits of your own can you see you have inherited from a family member?
● What is the “theory of evolution”?
● How have different types of scientists, such as botanists, zoologists, and geologists, contributed to the theory
of evolution?
POST-PROGRAM DISCUSSION QUESTIONS
● Was Darwin’s explanation of evolution “scientific”? Why or why not?
● How do you think the society in which a scientist lives might influence his or her views?
● What is your viewpoint on the idea of cloning and genetic engineering?
● What is the responsibility of society in current genetic research?
● How might our lifestyle today, the foods we eat, and the lack of physical activity create evolutionary changes?
Do you see current food allergies, asthma, or our resistance to antibiotics as part of future evolutionary
changes?
GROUP ACTIVITIES
Panel of Experts
Role-play a question and answer session with a panel of scientists to explore contributions to the theory of evolution and genetics. Assign individual students the role of Charles Darwin, Gregor Mendel, Friedrich Miescher,
Francis Crick, James Watson, Maurice Wilkins, Rosalind Franklin, and any other leading authority. Students who
are on the panel should research their individual’s contribution to the study of genetics. The remaining students
should develop questions to ask the panel.
INDIVIDUAL STUDENT PROJECTS
Origin of Species
According to Charles Darwin’s theory of evolution, the vast and diverse number of living species on Earth today
can be attributed to mutation, adaptation, and survival of the fittest. Read Darwin’s book On The Origin of
Species. What evidence can we see in the natural world that might support this theory? Write a short report
that summarizes your thoughts and opinions regarding Darwin’s theories.
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Genetic Mutation and Disease
Explore the concept of genetic mutation and how it relates to diseases such as cancer and Down syndrome,
the theory of evolution, gene therapy, etc. Choose a subject that is of interest to you and present your findings to
the class in an oral presentation. Create a poster, fact sheet, or other visual material to support your
presentation.
INTERNET ACTIVITIES
Genetics Today
Use the Internet to research a current event regarding cell reproduction such as reproductive or therapeutic
cloning, gene therapy, genetic engineering, etc., and present your findings to the class in a PowerPoint presentation or one-page summary report.
Human Genome Project
Learn about the current findings of the Human Genome Project. What information has been established? How
can this information benefit modern medicine? Develop a futuristic, hypothetical therapy or treatment based on
the discovery and mapping of a specific gene.
ASSESSMENT QUESTIONS
Q: What are the four key components of natural selection?
A: Variation, competition, fitness, and adaptation.
Feedback: Darwin believed that all living things evolved over millions of years through a process known as
natural selection.
Q: Chromosomes are made up of DNA molecules. (True or False)
A: True
Feedback: Chromosomes store all of the cell’s genetic information.
Q: Mendel crossbred _________ in his famous genetic inheritance experiment.
(a) flies
(b) peas
(c) bacteria
(d) finches
A: (b)
Feedback: Through his experiment with pea plants, Mendel discovered that individual characteristics are passed
down through generations. Sometimes a characteristic can appear in the next generation and sometimes it may
not appear until several generations later.
Q: Who discovered the concept of dominant and recessive traits?
(a) Gregor Mendel
(b) Charles Darwin
(c) Friedrich Miescher
(d) Watson and Crick
A: (a)
Feedback: The concept of dominant and recessive genes was discovered by Mendel through his experiments
with pea plants. One experiment in particular was crucial to the discovery. Mendel discovered that when he
crossed a round pea with a wrinkled pea, a partly wrinkled pea was not produced. Instead a round pea was
produced from that combination. When the peas of that generation were crossed, a wrinkled pea would appear
in the succeeding generation.
Q: What were the two fundamental ideas behind Darwin’s theory of evolution through natural selection?
Answer/Feedback: The two fundamental ideas were that “like begets like,” meaning that each species will
produce its own species. The second idea was that there is variation within species. It is because of the variation
that there is the process of natural selection. Through this variation, some species within an environment are
more likely to survive than others. Through time, the species evolves to better survive in its environment.
Q: How did Darwin’s voyage on the H.M.S. Beagle to the Galapagos Islands affect his work?
Answer/Feedback: During his voyage, Darwin was able to observe the variety of nature within different
species. His discovery of a new breed of finches led to his search for a logical explanation for how a group of
closely related birds could diverge into a new species on an isolated island. Darwin identified 13 species of
finches in the Galapagos Islands. This was confusing, because he knew of only one species of this bird on the
mainland of South America located 600 miles to the east of where they had all supposedly originated. The link
to a common ancestor sparked the idea of a species changing over time to produce a new species. After many
generations, they changed anatomically in ways that allowed them to get enough food and survive to reproduce.
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Q: The __________________ was the merging of Mendel’s and Darwin’s theories.
(a) Theory of Evolution
(b) discovery of the DNA molecule
(c) Origin of Species
(d) modern synthesis
A: (d)
Feedback: The modern synthesis showed how fundamentally Mendelian genetics could provide the basis for
evolutionary change.
Q: Who is credited for the discovery of DNA?
(a) Gregor Mendel
(b) Charles Darwin
(c) Friedrich Miescher
(d) Watson and Crick
A: (c)
Feedback: Friedrich Miescher was a Swiss biologist who, in 1868, carried out the first purposeful chemical
studies on the nuclei of cells.
Q: Scientists have discovered the purpose, but not the function, of each part of a DNA molecule. (True or False)
A: False
Feedback: The DNA is organized into stretches of genes: stretches where proteins attach to coil the DNA into
chromosomes, stretches that allow a gene to be activated or deactivated, and large stretches whose purpose is
unknown to scientists.
Q: Darwin’s theory of evolution was in direct conflict with the _____________ Theory.
A: Creation
Feedback: During the time of Darwin, the popular belief was that all of life was created by God. Creation
science is a belief that God created the Earth and all the creatures in it. Technically, it is not science because
creation by God or another divinity does not give concrete scientific explanation of life’s origin. Rather, it is an
explanation consistent with religious beliefs that an intelligent creator, God, exists and created the universe.
ADDITIONAL RESOURCES
Works of Charles Darwin
www.zoo.uib.no/classics/darwin.html
Basic Principles of Genetics: Mendel’s Genetics
http://anthro.palomar.edu/mendel/default.htm
Mendel’s Experiment and Mendel’s Law
www.mendel-museum.org/eng/1online/room4.htm
A Science Odyssey: You Try It: DNA Workshop
www.pbs.org/wgbh/aso/tryit/dna
The Franklin Institute Online: Living Things
www.fi.edu/tfi/units/life
Human Genome Project Information
www.ornl.gov/TechResources/Human_Genome/home.html
BOOKS
The Cartoon Guide to Genetics by Larry Gonick. Harper Perennial, 1991. ISBN: 0062730991
The Origin of Species by Charles Darwin. Grammercy (reprint), 1998. ISBN: 051712320
Spark of Life: Darwin and the Primeval Soup by Christopher Willis and Jeffrey Brada. Perseus Publishing,
2001. ISBN: 0738204935
OTHER PRODUCTS
DNA
Fifty years ago, two unknown scientists ran into an English pub shouting that they had found the secret of life.
Jim Watson and Francis Crick were not exaggerating. Narrated by Jeff Goldblum, this series looks back on the
achievements that launched a new era in biology and human life itself. Along with an incredible array of
renowned scientists, including five Nobel Laureates, these programs use beautifully realized animations and
reconstructions of key experiments to reveal the molecular basis of life in a way never seen before. 5-part series
(57 minutes each) © 2003
Order #: 32203, www.films.com, 1-800-257-5126
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Cracking the Code: The Continuing Saga of Genetics
Can life can be summed up in a code? The science of genetics is founded on that idea—and the code has
been broken. This five-part intro-level series reveals the history and development of genetics, reconstructing
its journey from the 1700s to the cutting edge of 21st-century microbiology. Featuring detailed accounts of
genetic advances—from Mendel’s peas to Bt-treated corn—each program presents complex technical analysis
and reinforces key concepts using lively, scientifically precise animation. With an emphasis on real-world genetic
applications, challenges, and dilemmas, this series conveys a panoramic view of today’s preeminent life science.
Viewable/printable instructor’s guides are available online. 5-part series (30 minutes each) © 2003
Order #: 36222, www.films.com, 1-800-257-5126
Secrets of the Sequence Video Clip Collection
Ideal for launching lectures and discussions, this four-part series of video segment compilations provides an
inside look at progress in genetic science. Through case studies and interviews with many of the field’s most
respected authorities, the series explores medical, biological, and agricultural research—while reporting on
the profound moral, ethical, and legal questions this research raises. Produced in collaboration with Harvard
University, The Medical Research Council/Laboratory of Molecular Biology, University of California San
Francisco, University of Michigan, University of Wisconsin-Madison, and Virginia Commonwealth University.
4-part series (60-73 minutes each) © 2007
Order #: 38977, www.films.com, 1-800-257-5126
Charles Darwin and the Tree of Life
Marking the 150th anniversary of the publication of On the Origin of Species, this program shows how
Charles Darwin developed his theory of evolution and explores its ramifications in today’s scientific community.
Renowned natural history interpreter David Attenborough travels the globe, examining fresh evidence for
Darwinian thought and illustrating why it is more relevant than ever. Viewers encounter findings from a wide
range of disciplines, including paleontology, biogeography, anatomy, and embryology, as well as early controversies surrounding the study of plate tectonics. Spectacular wildlife footage reveals fascinating animal behavior
and helps depict the theory that changed the world’s thinking. A BBC/Open University Co-production.
(52 minutes) © 2009
Order #: 40443, www.films.com, 1-800-257-5126
In Darwin’s Garden: Evolutionary Theory and Nature’s Laboratory
Journeys to exotic places shaped much of Charles Darwin’s thinking, but of equal importance were the humble
experiments he performed—quite literally—in his own backyard. This three-part series re-creates many of
Darwin’s crucial studies of plants and animals which he undertook near Down House, his home outside London.
Presented by British science interpreter Jim Doherty, each episode features Darwin’s venerable manor as a narrative hub while venturing to other research locations for commentary from modern scientists. Original Open
University broadcast title: Jimmy Doherty in Darwin’s Garden. 3-part series (58 minutes each) © 2008
Order #: 40622, www.films.com, 1-800-257-5126
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