The Evolution of a Biology Course:

From Student Passivity to Student Accountability

Judy Moore and Eric Mould

 

 

When two instructors who had been lecturing in multiple sections of introductory biology felt themselves going stale, they redesigned their curriculum so that students learned actively through collaborative group work. In this article, they describe the process of transforming the class to a more student-centered format, and describe the ways they built in assessment activities. Data show increased retention and better grades for students who experience the new, collaborative approach.

Prior to Spring, 1987, the general introductory biology course we taught at Yakima Valley Community College was a standard lecture/lab course for majors and nonmajors. This course covered the scientific process and basic phenomena common to all living things: evolution, ecology, cell structure and function, genetics, and energy relationships. The goal had been to teach not only the subject matter of biology, but an appreciation of what science is and an ability to see it at work in their lives. This course had a conventional format with three lectures and two labs per week. We had formulated a comprehensive set of lectures as the underpinning of the course and strived to make the lectures extra clear to students by providing them with lecture outlines.

After several years of teaching with this format, we (the two instructors teaching most sections of this course) began to see that the instructors were doing most of the work, while students were attending class as passive observers. Although this approach did stimulate a small number of our students, we were disappointed in the results of our labors. Few students were reading the text. Most students came to class unprepared. Only a minority in the class were engaged in attempting to understand and discuss the material. Most students could handle objective questions on tests, but their performance on synthesis and application questions was disappointing. Student retention in the course was above average for the institution, but we were losing twenty percent of the class in a fairly steady attrition throughout the quarter.

Moreover, when we first designed the course, our creative juices flowed and our excitement was high working on handouts and polishing lectures. In time however, the class became routine: distribute handouts, check visual aids, deliver lectures, give tests, and then repeat it all again the next term. So in addition to the frustration of seeing limited results of our efforts in terms of student excitement and performance, we were getting bored. We hungered for a radical alteration in the way we interacted with our students. We needed a method that would address our desire to improve student performance and to revitalize our interest in teaching.

Course Restructuring

Before restructuring the course, we thought about our overall goals. We wanted students to be able to refer to sources and think about the material critically, to interact with each other in a supportive learning environment, and to learn some basic biological concepts. It was essential that students come to class prepared and ready to actively discuss course materials and issues with each other. As students became information gatherers, critical thinkers, and classroom performers, they would learn the subject. To achieve these goals we saw that we had to give up our roles as performers and to serve more as coaches or facilitators of the class. Therefore, we decided to abandon our lectures and move to a discussion-centered approach.

To be effective in classroom discussion, students would have to do more than simply read the textbook. They would have to study it and think about it. So for each weekly unit we wrote a series of questions that students would be required to complete in order to come to class. These worksheets became the source for both discussion and assessment. We wanted students to spend class time engaging in meaningful discussion rather than simply restating what was in texts. This could be accomplished by exposing them to a variety of texts covering the same biological topics. We decided to ask students to choose any one of several biology textbooks available in the bookstore. They would read outside of class and then compare answers in class with students using different texts. Because students would be explaining their answers to classmates using other sources, they would need to understand what their text says. We wanted students to appreciate that several different and equally valid ways exist to express the same idea.

Because we had already written our major subject matter objectives in the form of lecture outlines, we easily shaped the content sequence of the course in a preliminary way. However, we were interested in a number of new outcomes for our students. We wanted students to be able to speak, write, and think critically about major biological concepts. To promote these abilities, we rewrote our former study questions. We made them more open-ended and set up an environment where students would get daily practice in speaking, writing, and thinking. During each class meeting every student would practice explaining material to other students and consider rewriting answers to questions posed on the worksheet. Students would help each other to think through and then articulate the subject matter, while the instructor would serve as a listener helping students to evaluate each other's performances. The teacher would also help the class compare results, resolve differences, and understand areas of difficulty. In this new collaborative approach, students would be evaluated on their daily classroom speaking and writing performances, as well as on a written essay exam given at the end of each week.

Since Biology 101 is prerequisite to a number of other biology courses, we consulted with our colleagues in the department about our course content. They agreed with us concerning subject matter and were confident that the content covered would remain rigorous. These discussions did not end with content issues but expanded to an ongoing dialogue about our goals and mission as biology teachers. Although everyone does not always agree, we have found the conversation with our colleagues to be an unexpected benefit of our class restructuring.

 

Building Collaborative Learning into a Weekly Schedule

We agreed that development of knowledge in student groups would be the structural cornerstone of the course. Over the next couple of years, we developed a weekly schedule that would be a mix of individual and group work. (see Table I below and Appendix I) Now we hold students accountable for coming to class prepared to discuss the weekly concepts. Our weekly format includes class time in small group work, lab, seminar discussion, and testing. Typical class size for one section of this course is 28; however, with the addition of extra seminars and labs we have accommodated as many as 60 students.

 

Table I

Weekly Schedule

MONDAY

TUESDAY

WEDNESDAY

THURSDAY

FRIDAY

75 minutes

110 minutes

50 minutes each

75 minutes

50 minutes

Group Work

Lab

Seminar

(2 groups)

Oral Quiz, Group Presentations, or Quiz Game

Essay Exam

Preview Next Week

Distribute Worksheets and Reading Assignments

Individual Preparation: Groups work best when every individual is prepared. So before each class week begins, students must spend time and effort reading and answering questions on the worksheet. For example, during the week we cover evolution, one of the concepts we want our students to understand is how the evolutionary process works and how to apply it to real examples. Therefore, before Monday students answer their worksheet questions, such as "List the steps in the process of evolution;" and then they must attempt to apply this process to real examples such as "How did roses develop thorns?" (See Appendix II: evolution worksheet, questions 4 and 5.) Most students are able to list the steps of the evolutionary process, though their understanding may be rudimentary. While they will attempt to apply this process to the suggested examples on their own, clearly their understanding is, at this point, incomplete. Typically, we expect students to come to class each Monday in the quarter with a basic understanding which needs to be enhanced through group work.

On Mondays, we allow students to enter the class only if they have completed their worksheet assignment. By asking unprepared students to leave, we avoid potential conflicts between "hitchhikers" and those students who are prepared to do the work. Students who are prevented from participating on Monday may return to class the following day with completed assignments, but are not allowed to earn points for the group or individual work that they missed. We make it clear in the syllabus and on the first day of class that this level of participation is an absolute requirement. Students soon recognize that their worksheet is preparation to ensure that they are actively and productively engaged in class, not something to complete merely to avoid losing points. Our experience has shown that after the second week all students come to class prepared.

As soon as class begins on Monday we give an individual mini-quiz. We choose a question that a student who has worked on and has thought about the worksheet should be able to answer. In the example above, an appropriate mini-quiz question might be, "List the steps for the process of evolution." Because the purpose of this quiz is to reinforce those who have come prepared and is not to test rote memory, we often allow students to use their own worksheet while taking the quiz. We realize that there are many correct answers, depending on which text each student uses.

Group Work: Each Monday, following the mini-quiz, we assign students randomly into groups of four to five. Student groups engage in answering a question from the weekly worksheet or in developing a synthesis statement designed to draw together several concepts from the worksheet. The group's task involves seeking answers or solutions that represent the collective judgment and labor of the group as a whole. In reaching consensus on these tasks, students are engaged in intense intellectual negotiation. They stand up for their ideas and revise them in light of data offered by others. For instance, different texts may describe the process of evolution in three, four, five, or even as many as seven steps. At first most students find this troublesome and are concerned with finding the "right answer." After assurances from us that all the different versions are correct, they begin to compare, and most students can then see that they are simply different ways of explaining the same process. Then the groups are able to apply the steps of this process to real examples as part of their group task because they understand the process rather than just having memorized some steps (see Appendix II: evolution worksheet, question 5).

Results of group work are shared and discussed with the entire class each day, either verbally or in writing at the chalkboard. We design group activities that can be completed in a class period, and we give students clear time limits for each task. For example, we may give students fifteen minutes to make a diagram illustrating a particular process or to write a paragraph explaining a concept on the worksheet. The instructor travels from group to group for short periods, but we have found that when we join a collaborative group, we can easily take away students' authority and confidence.

We have a variety of activities that each group may be required to do later in the week on Thursday. One of these is an oral quiz, in which one individual in each group is randomly selected to answer out loud a question from the worksheet. Since the groups don't know which question or which individual will be asked, it is the group's responsibility to ensure that all members can articulate good answers for every question. While groups have most of class time Monday and a few minutes on Thursday to prepare, most voluntarily meet outside of class even though ours is a commuter campus with working students. The students take an oral quiz on Thursday and earn their group a grade. In our evolution example, a student in one group would be asked to explain orally to the entire class "how roses developed thorns" using the steps of Darwinian evolution. The whole class is next asked if this answer is complete and accurate. The instructor then assigns a grade and provides a justification for the grade earned. Students are very clear as to how they are being evaluated. Another type of group assignment is the formal group presentation, where on a Thursday each group of students will give a presentation on a topic to the whole class. We assign each group a different aspect of the weekly work and require additional library research, use of visual aids, and participation by all members in the finished presentation. Some weeks, we engage students in a quiz game along the lines of the TV show "Jeopardy." Students generate questions on Monday that we post and then use later in the week when we moderate the game. Again, students play the game in teams and are graded as a team. All of these group activities are designed to allow the entire class the opportunity to hear and comment on the weekly material.

Working in groups is not always easy for students, but with practice many students build the skills for working with others. This course requires daily interaction, and students get better at working together throughout the quarter.

Reinforcing Activities: Lab, Seminar, and Written Test: A variety of reinforcing activities during the week requires the students to think about the content in different ways. Group work concerning items on the weekly worksheet occupies two class days per week, Monday and Thursday. One of the other days is a two-hour lab where students gather data related to the weekly topic. We devote a fourth day of the week to seminar. At registration the class of 28 is divided into two seminar groups of 14 students each. A class of 60 would necessarily be broken into four groups. Each seminar group meets for one hour weekly. In seminar the students discuss essays which may or may not be directly related to the weekly topic examined on the worksheet and in the text. Students purchase a paperback collection of essays by authors such as Gould or Quammen and read one each week for the seminar discussion. To enter seminar, a student must show a one-page journal entry in response to the essay. Students assess their own performance in the seminar discussion and that of an assigned peer at the end of each seminar. They are asked to pay attention to the quality of comments made regarding understanding of the essay and level of participation in the seminar. Finally, each Friday, there is an individual essay exam. When students turn in their exam papers, they receive their worksheet and assignment for the following week.

Changing Roles and Accountability

One backbone of collaborative methodology is that students develop responsibility for their own learning and that of their fellow classmates. This is accomplished by the expectation of accountability: individuals need to come to class prepared in order for groups to excel. When the week begins, individual accountability assures that only those students who are prepared will enter class and take the short, written mini-quiz. Then group accountability becomes paramount as group members begin to trade information and ideas in order to produce a written and/or oral product they share with the class. Attendance is rewarded through daily, graded activities. Following the group accountability on daily work, the Friday essay exam again rewards individual achievement.

These various levels of accountability are highly integrated. Well prepared individuals make productive small groups which in turn energize the entire class. And students perform better as individuals because they have worked well in groups. Because each individual and group has been held accountable and has witnessed other groups perform, subject matter is reinforced. Not only are students learning biology, but they are learning the responsibility involved in being a member of a community of learners.

As collaboration changes the accountability of students, it also changes the role of the teacher. As teachers, we serve as classroom managers, to see that groups are functioning, to serve as critics when groups report, and to intervene and clarify if student groups become confused or bogged down.

Assessment

Daily assessment of student learning as individuals and in groups is purposefully integrated into this process (Table II below). We grade individuals on their preparation for the week's work in the form of five-point Monday mini-quizzes. At the end of each week we determine the bulk of the student's grade by his/her performance on the Friday 50-point essay exam which each student takes independently.

We consistently monitor the progress of small groups by roving around and suggesting, prodding, and encouraging. On Monday we expect each group to share a short "Group Write" or verbal answer with the entire class, which may be worth five or ten points. We more formally evaluate group work on Thursday during the oral quiz, group presentation, or quiz game and allot 15 to 25 points per student each week. All students within a group receive the same grade, and only students who have been present all week are allowed to participate. We evaluate group work orally and allow time for the help of additional comments from peers so that the entire class can see what is expected, what grade was received, and why. Even though only twenty percent of the total points for the week is based on group work, students know that when they engage in and contribute to the group, they will perform better on the individual Friday exam.

 

Table II

Weekly Schedule of Assessment

       

MONDAY

TUESDAY

WEDNESDAY

THURSDAY

FRIDAY

5 points mini-quiz

5-10 points lab write-up

10 points seminar participation

15-25 points group activity

50 points essay exam

 

What We Learned

About Content Coverage: The shift in paradigm which has taken place in this course has brought many surprises. We found that we had underestimated the amount of content that could be covered in an introductory course. When teachers "lecture" on all the material covered in a course, class time limits the amount of coverage. When students are accountable for their own reading and research outside of class, class time is used for discussing, clarifying, and synthesizing. Many more concepts can be "covered"—and in greater depth. Since the questions on the weekly worksheets are critical to determining what students might ultimately learn, we are continually evaluating and revising the questions. We also continually revise seminar readings. We have increased the topics covered in many areas and have eliminated some nonessential details in others. The shape of the course content has definitely evolved over time.

About Expectations for Student Learning: We had not anticipated the development of higher cognitive skills that takes place when students are collaborating. The students perform well on synthesis, analysis, and application questions on the Friday essay exam because they have been practicing these activities in groups all week. In the old version of this course where we simply lectured and the tests were multiple choice, students were rewarded primarily for memorizing facts. In this new approach, the facts have become less important than conceptual understanding and thinking. By explaining biological processes to each other during the week, students clarify their own understanding and improve their use of terminology, which enhances their ability to write essay exams. Using our evolution example, students are asked to apply the process of Darwinian evolution to an example that they have not seen (see Appendix III: quiz 2, question 7). Very rarely are students asked to simply state memorized information on the exam because the goal is to demonstrate understanding, not memorization skills.

About Instructor's Preparation: When this class was lecture format, we judged our success on whether we had given a good lecture or not: "Boy, I really wowed them today!" Our satisfaction now comes from a class session where students are actively sharing and discussing and teaching each other: "Boy, did they do a good job today!" This does not mean we never lecture. Occasionally, when all the groups are struggling with a concept, we offer a mini-lecture which helps the groups get back to work. Our goal is merely to get groups back on track, not to provide all the answers. Our "work" now is done mostly outside of class planning assignments and classroom activities that make this rich interaction in class possible. During class we find out how well we did.

One of the most exciting aspects of this approach is both we and the students recognize that each day and each class period are unique and spontaneous. Teaching two or three sections of the same course every day is always interesting because the course agenda is so student-centered. Our basic assignments and expectations are the same, but no two groups of students interact and present information in the same way. Students realize that the process of wondering about, discussing and clarifying ideas in biology is more important and more fun than merely memorizing facts. They tell us that coming to biology class is fun and exciting because every day is different, and they are never sure exactly what will happen. Seeing student excitement about the subject day after day is enormously reaffirming.

We have found that our workload has not changed in quantity but has changed drastically in quality. Rather than preparing for our "performance" in class, our time before class is spent preparing a learning environment. Rather than lecturing in class, our energy is used to interact directly with students and guide their efforts. Less of our time both in and out of class is spent with the subject matter, and more time is spent in helping the groups to work together effectively. While our workload has increased because of the effort to take attendance and to prepare and grade many daily quizzes and a Friday essay exam, we have minimized our added workload by grading group work in class and making students responsible for answers on their own worksheets. One of the benefits of the efforts spent taking attendance and grading frequently is that we get to know our students more quickly.

Once students discover the joy of learning by discussing they seize opportunities to spend more time on task. We invite all students from any section of this course to attend a review session in the student union building on Thursday evening before each Friday exam. At least two instructors are present each week, and as many as 80 students attend. Students form their own study groups at the tables, and often choose to work with students from other classes. Our role at this session is to move around to the various groups to offer encouragement and facilitate students teaching each other. For example, if a group has arrived at a good understanding of what occurs during the light-dependent stages of photosynthesis, we identify them as the "experts" to help other groups who are still struggling to grasp this process.

About Institutional Gains: One of the successes of the collaborative approach has been a 10-15% increase in student retention in this introductory course. We find that students who withdraw (one to three per class) do so very early, usually within the first two weeks. Initially we were surprised by this, but found that those students who left did so when they realized that there were high expectations in terms of attendance and daily participation. Students who remained beyond the first two weeks found themselves engrossed in a community of learners, an environment they rarely choose to abandon.

About Student Gains. Although we don't set out to work formally on developing group skills, they improve because the students get practice virtually every day. Not surprisingly, many students at first express frustration about this learning strategy. On a course evaluation form, one student summarized the remarks of many by saying, "Why should my grade be determined by the poor performance of one member of my group?" Another student pinpointed an additional frustration with group work. "I didn't like the part about students teaching students. I have been taught by listening, taking notes, and memorizing the right answer." Striving for the "right" answer was a problem for many students throughout the quarter, and expressed in their written evaluations of the course. This response may reflect students' lack of confidence in their own ability, which also makes them uncomfortable with an answer developed within a group. Or, it may reflect students' views of knowledge, learning and the appropriate roles for students and teachers. (See William Moore's article on intellectual development later in this Handbook.)

Some students are never totally comfortable working with and (necessarily) trusting others. But they understand that their success in the class is dependent upon effective group interactions, and so they learn what they need to do to become productive group members. As one stated, "I may not have liked working with everyone in the group, but for one week I would love them." Even though they continued to clamor for us to give them "right" answers ("I liked it most when you lectured"), students realized they had to become efficient in their groups. "Once we stopped complaining about our ruined weekend we usually saw that we generally agreed on most of our answers and needed to argue about only a couple of questions." Fortunately, most students also commented that their dismay over their workload was balanced by what they accomplished during the variety of activities in the classroom.

Most interesting (and gratifying) is the development of a sense of community in the class. Student comments include the following:

...discussions were most helpful. They let me see different people's views.

The whole class contributed to my learning...it really helped to know different people and their ideas.

This is one of the very few classes in which I knew the other students ... we met often in and out of class.

I liked the idea of everyone being involved, I had to stop and think rather than just go with the first thing that pops into my head or something the teacher said.

All of these statements reflect an appreciation of fellow students and an understanding of the value of a community learning together. In the end, the strength of the collaborative approach may go beyond the more obvious improvements in such things as subject mastery and student retention. Perhaps the fact that students learn to examine and develop knowledge together and value the contributions of others in the process is the most important lesson of all. One student indicated it could even be enjoyable: "I really enjoyed the class—the most fun I have had sitting up and awake."

Our restructuring of the introductory biology course has "upped the ante" in terms of what is expected of students. They are required to maintain nearly perfect attendance and to come to class prepared and ready to work. They must not only master concepts of biology but while doing so must also develop communication skills and the ability to work productively with others. Finally, our students are required not only to master the factual aspects of the discipline but to think about them in analytical and critical modes. The results of their efforts have been both rewarding and enduring, best summarized by the comments of one initially reluctant student:

I signed up for Biology 101 with a bit of resentment at being required to do something that seemed irrelevant to my long-range career goals. Biology turned out to be much more interesting than I expected due in large part to the collaborative learning structure. Explaining what one thinks one knows to someone else clarifies and reveals gaps. Being able to get questions answered within the group and searching together for answers was motivating and allowed more access to the instructor because most of our questions were being answered from within the group.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix I

BIOLOGY 101

 

Instructors: Office Hours:

Judith K. Moore G103B, 575-2404 9:30 Daily

Eric D. Mould G103C, 575-2404 2:10 Daily

Michael Harves G103A, 575-2404 8:30 Daily

 

Welcome! You are about to embark on a journey that may change your view of life and will surely change your view of science and learning. In this course you will be allowed to generate knowledge about biology with your peers. Your instructor will be a learner too, a facilitator, and an occasional resource for information. This method of teaching will allow you to practice thinking, speaking, and writing as you formulate answers to weekly worksheet questions and then on Friday you will take an essay exam. You will be actively involved everyday in a variety of different assignments so class is fun and you won't want to miss. You will probably learn much more biology in this course than in others where an instructor lectures to you. You will soon feel a sense of "community" with your classmates and your instructor.

Weekly Schedule:

Monday: You are accountable to arrive with your reading done and your

worksheet assignment completed. You will be put with a group of

five congenial students who will work together all week in

discussing the concepts on the worksheet. You'll do some group

writing exercises and probably take a short quiz.

Tuesday: This is lab day so bring your lab packet and go to the lab. Lab

work relates directly to the concepts on your worksheet. This

is your chance to gather some data, interpret it and apply it to

major concepts you are discussing.

Wednesday: This is seminar day so come prepared with a written response to the assigned essay. These responses should be kept in your journal.

Thursday: This is group accountability day. Your group will have a share of class time to finish preparing for the graded assignment. Your group will either be 1) given an oral quiz, or 2) present a formal presentation to the class, or 3) play "Jeopardy," or 4) do a written group exercise. All members of the group receive the same grade so helping to prepare your team members can enhance your own score. Thursday evening from 7:00 to 9:00 p.m. the instructors and many of your classmates will be meeting in the Student Union Building (HUB) to discuss the week's work in preparation for the Friday written exam.

Friday: This is final individual accountability day. You will take a

written essay exam over the week's material. After finishing

your exam you will pick up the new worksheet so you can do your

reading and prepare your assignment before arriving in class the

following Monday.

 

 

 

 

 

Quarterly Schedule of Topics:

What is Science? (Scientific Method)

Evolution

Chemistry of Living Things

Origin of Life/Membranes & their Functions

Energetics: Enzymes & Cellular Respiration

Energetics: Photosynthesis

Reproduction/Cell Division (Mitosis & Meiosis)

Mendelian Genetics

Molecular Genetics (DNA, RNA, Protein Synthesis)

Presentations on Environmental Issues

Textbooks

Five different introductory biology texts are available in the bookstore. You may purchase any one of these. We do this so you will have many different resources available to you as you work in your small groups during the week. Everyone also needs to purchase a lab packet.

Rules on Testing and Grading:

A quiz is planned for each Friday. This will cover all class activities for that week. It will take 30 minutes and be worth 50 points. These will be no make-ups on Friday quizzes or any other classroom activity. If you choose to take the optional final exam, that score can replace your two lowest Friday Quiz grades. Lab attendance is mandatory; 10 points will be deducted for each lab missed. Three consecutive absences will result in your automatic withdrawal. Grades are based on a percentage of total possible points:

90+% = A; 80-89% = B; 70-79% = C; 65-69% = C-; 50-64% = D.

Teacher Responsibilities:

Present an environment for learning. Give fair assessment of student progress. Supply printed materials the day they are used in class.

Student Responsibilities:

Attend class regularly (like every day). Prepare for and take all quizzes when scheduled. Read assignments before coming to class. Participate in class discussions. Keep seminar journal up-to-date. Be respectful of fellow students' viewpoints and learning styles. Come to class with worksheet assignment done and reading completed. Observe the rule of academic honesty. Simply stated: Don't cheat!

 

 

 

 

Appendix II

WORKSHEET- EVOLUTION

 

  1. How did each of the following influence Darwin in the development of his?

Charles Lyell

voyage on the Beagle

Thomas Malthus

Lamarck

artificial selection

Alfred Wallace

 

2. Lamarck based his erroneous evolutionary hypothesis on teleological statements involving the passing of acquired characteristics from one generation to the next. Darwin's theory is based on the passing of inherited genetic characteristics from one generation to the next. Which of the characteristics listed below are acquired and which are inherited? Is it possible for any of these to have both acquired and inherited components? Explain.

A broken toe

Increased bicep muscles in individuals who do pull-ups

Increased proficiency in playing the clarinet

A beard on a man

Docking (cutting off) tails of cocker spaniel puppies

Attaining a height of 6'4" in humans

Development of gray hair in elderly people

 

 

 

 

 

 

 

  1. List and describe Darwin's four points as discussed in class.

 

4. Find any text's description of Darwinian evolution - list the steps for the process of evolution and compare to the four provided in class.

 

 

 

5. Keeping in mind the major driving forces of Darwinian evolution (Darwin's 4 points) explain how the following characteristics could have evolved. (Note: It is not OK to simply state why these characteristics are nice to have, you must explain how they could have actually evolved, using Darwin's 4 points.)

Presence of thorns on rose bushes (ancestral plant had no thorns)

(1)

(2)

(3)

(4)

Transition of moth population in the British countryside from the light variety to the dark form.

(1)

(2)

(3)

(4)

Resistance to drugs in bacteria (bacteria that used to be killed by penicillin are now resistant to this drug).

(1)

(2)

(3)

(4)

Development of large brains in humans (ancestor had a brain about half as big as today's human).

(1)

(2)

(3)

(4)

WORKSHEET: EVOLUTION

Paqe 3

6. One of the hallmarks of the evolution of ostriches from their primitive bird ancestors is the development of knee callouses. Callouses are important because they help protect against open sores when kneeling during nesting, etc.

Develop two explanations for the evolution of knee callouses in ostriches--first from teleological Lamarckian perspective (which is of course incorrect) and secondly from a plausible Darwinian viewpoint.

Lamarckian: Darwinian:

 

 

 

7. Why is variation so important to the success of any population?

 

 

 

8. What does "fitness" mean in an evolutionary sense?

 

 

 

9. What are sexual dimorphism and sexual selection? Give an example and explain how they have evolved in many species of animals and have directed the evolution of a species.

 

 

10. Define in your own words what is meant by the terms divergent evolution and convergent evolution.

Divergent Evolution:

Convergent Evolution:

 

 

 

 

 

 

 

WORKSHEET: EVOLUTION

page 4

 

 

Now determine which of the following pairs of organisms show examples of either of these two evolutionary processes (Note: specify which characteristics led you to your answer):

Houseflies/Bats

Deer/Elk

Polar Bears/Black Bears

Whales/Sharks

11. Write a clear concise narrative describing the steps involved in the process of speciation.

 

 

 

 

12. What are geographic isolation and reproductive isolation (how are they different)? What does isolation have to do with speciation?

 

 

 

 

 

 

13. What does is mean to be "selected for" or "selected against" in an evolutionary sense?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix III

Biology 101 - Quiz 2 - 50 pts. Name

Instructor

 

 

 

  1. Describe two influences on Darwin in the development of his theory. (4 pts)
  2.  

     

     

     

  3. For each of the characteristics listed below, indicate with (A) if it is acquired, or (I) if it is inherited, or (B) for both. In one short sentence, iustify your answer. (10 pts)
  4. Nolan Ryan's ability to throw a fastball

    the pattern of spots on a trout

    callouses on the knees of a floor scrubber

    good night vision in owls curly hair

     

  5. What do we mean by the term "fittest" in an evolutionary sense? (4 pts)
  6.  

     

     

  7. Describe the steps of speciation. (4 pts)
  8.  

     

     

  9. Which one of Darwin's four points was demonstrated in lab by counting the corn kernels? Explain. (4 pts)
  10.  

     

     

     

     

     

     

     

     

     

     

     

     

  11. Describe how a human hindlimb and an alligator hindlimb are similar and dissimilar. (4 pts)
  12.  

     

     

     

     

     

     

  13. After the second world war, the pesticide DDT was used extensively to kill flies all over the world and it worked very well for a while. But as you can now see there are still plenty of flies around but DDT is no longer used. Not only is it very bad for other organisms and an environmental disaster, but it no longer kills many flies; they are resistant to it. Using Darwin's four points (each clearly) explain how this happened. (16 pts)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8. Explain how both Lamarck and Darwin would explain the development of webbed feet in ducks. (4 pts)