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BROADENING THE SCOPE: INCORPORATING BIOCHEMICAL CONCEPTS
INTO THE HIGH SCHOOL CHEMISTRY CURRICULUM
BY

Sara Jane Dallas

A THESIS

Submitted to

Michigan State University

in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE

Division of Science and Math Education

College of Natural Science

1998

Merle fieidemann

ABSTRACT

BROADENING THE SCOPE: INCORPORATING BIOCHEMICAL CONCEPTS
INTO THE HIGH SCHOOL CHEMISTRY CURRICULUM

BY

Sara Jane Dallas

The high school chemistry curriculum rarely makes connections to other
scientific disciplines. As a result, students fail to see the relevance of Chemistry

to other areas of study.

There are three purposes for including this unit on Biochemistry in the
Chemistry curriculum: 1. to make the chemistry course more interdisciplinary,
2. to make the laboratory experience more inquiry based and 3. to make the

course relevant to all students.

Students’ prior knowledge was assessed with a pretest. Student success was
evaluated by their performance on laboratory activities, a hands - on
assessment, and an objective unit test. Results of these assessments indicate
the students made connections to other scientific disciplines and were
successful in applying learned concepts to new problems. Also, results suggest
that students function and learn better in inquiry activities that provide some

structure.

Copyright by
SARA JANE DALLAS
1 998

For Joseph, without your support and endless hours of help,
I would not have fininshed.

 

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TABLE OF CONTENTS

LIST OF TABLES
LIST OF FIGURES
INTRODUCTION

Scientific Overview
Demographics

IMPLEMENTATION OF UNIT
Objectives and Activities
Outline of Unit

Audio Visual Aids

Implementation and Analysis of Student Activities
and Laboratory Exercises

Article Reading
Model Building
What Is It?
Diffusion
Exploring Enzymes
RESULTS AND DISCUSSION
Summary of the Biochemistry Unit Pretest
What Is It?
Evaluation of What Is It?
Diffusion

Exploring Enzymes

Page
vii

viii

9-20
9-11
11-12
13
13-20

14

14- 15
15-17
17- 19
19-20
21-40
21 -22
24-26
27 -28
28-32

32-35

RE

Analysis of Student Performance on Objective
Unit Test

Comparison of Success on the Objective Test
and the Labs

Comparison of Success on the Lab Evaluation
and Objective Test

CONCLUSION
APPENDICES

Appendix A - Chemistry Curriculum at Study School

Appendix B - Letter of Notification for Parents and
Students (UCRIHS)

Appendix C - Pretest and Results

Appendix D - Model Building

Appendix E - What Is It? and Teacher Notes
Appendix F - Diffusion and Teacher Notes

Appendix G - Exploring Enzymes and Teacher
Notes

Appendix H - Biochemistry Unit Test

REFERENCES

vi

Page
35-37

37-38

39-40

41-43
44-89
45-49

50

51-55
56

57-70
71-77
78-86

87-89
90-92

LIST OF TABLES

Page
Table 1 Data table of lab activity scores and 23
statistical information from the Biochemistry
Unit.

vii

 

 

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Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

LIST OF FIGURES

A scatter plot of the distribution of student
scores on the laboratory cluster What Is
It?

A scatter plot of the distribution of student
scores on the hands - on assessment.

A scatter plot of the distribution of student
scores on the laboratory cluster Diffusion.

A scatter plot of the distribution of student
scores on the lab cluster Exploring Enzymes.

A scatter plot of the distribution of student
scores on the unit objective test.

A regression between student performance
on all of the laboratory assignments and
performance on the objective unit test.

A regression between student performance

on the hands - on assessment and the
objective unit test.

viii

Page
26

29

31

34

36

38

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INTRODUCTION

Broadening the Scope: Incorporating Biochemical Concepts into the High
School Chemistry Curriculum has several objectives. The first objective was to
broaden the scope of the chemistry curriculum at my high school. The second
objective was to show students the interdisciplinary nature of science, as most
problems in science involve concepts from multiple scientific disciplines. The
third objective was to change from a predominately verification style of
laboratory experience to an inquiry based laboratory approach in my Chemistry
class. My final objective is to make chemistry relevant for students enrolled only

because their counselor said they need Chemistry to be admitted to college.

Most college bound students, regardless of their level of interest in science, will
take a chemistry class in addition to the core science requirements.
Unfortunately, prior to the inclusion of this unit into the curriculum, there was no
integrated science taught at the school where this study took place and the
Chemistry curriculum did not include Biochemistry. One of my principle
objectives was to encourage students to see the relationships between these
scientific disciplines. Hopefully, this will increase the relevance of science for
all of my students. Sterling and Davidson (1997) state that we need to “make
chemistry more personally meaningful to students who have no interest in
continuing the study of science.” This should be one of the universal objectives

of every science class.

Prior to April 1998, biochemistry was not taught at the study high school in

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anything more than a cursory review. A biochemistry unit was intended to fill a
gap in understanding of many of my students who could not explain what an
enzyme was, much less its function in a biological system. Also, students did
not understand that enzymes typically are reusable, and each catalyzes only
one type of reaction. Students were only vaguely aware of what the principle

biomolecules were and what the function of enzymes is in an organism.

The second objective I intended to achieve in designing and implementing this
unit was to increase the number of and change the nature of the laboratory
experiences. My intent was to move away from the traditional ‘verification' lab
and use more inquiry labs. Regarding verification labs, Allen, et. al, (1986)
states that “students were not stimulated intellectually because they only had to
recall their classroom work to do well.” This is exame what I want to avoid.
Instead, it was my goal to engage my students in more thought-provoking
activities. Ultimately, Allen, et. al, (1986) concludes that structured inquiry
experiments are important to improving both the critical thinking and problem
solving skills of students. Also, they are useful in reducing the number of
verification style experiments and the lack of interest they can inspire. I realized
early in the design of my unit that I needed to deemphasize the traditional
instructional approach to the laboratory. Leonard (1989) in a summary of
current literature on investigative laboratory instruction techniques, indicates
that there are three things required in a successful laboratory experience. First,
the student needs to engage in a number of scientific inquiry processes such as
making observations, making inferences, analyzing data and presenting data
etc. Secondly, students need to be engaged in the experimental process. They

need to be allowed and encouraged to make hypotheses and to manipulate

variables. Finally, the instructor needs to be sure to include specific scientific
concepts into the laboratory experience. Often, it is assumed by many
instructors that students in an honors chemistry class will always do well.
However, some of them do struggle and need to see material presented in a
variety of ways. According to Woolfolk (1987), instructors need to be aware that
individual students approach problems differently. Some students focus on the
whole and have difficulty analyzing the problem. Furthermore, there is no one
teaching method that works with all students. Instead. utilizing more
instructional techniques will likely engage more students. Material presented
and then reinforced with a hands - on approach, encourages all students to
discover the concepts more independently. With this approach, students are
provided with the opportunity to create their own knowledge base. Because of
the numerous opportunities for laboratory inquiry, this unit was a natural way to
explore effective alternative methods of instruction and assessment that would

engage all students in the learning process.

One of my intents in developing this unit was to increase the number of
instructional approaches I utilized in my teaching. I wanted to move away from
a focus on lecture and towards a focus on exploration, inquiry and discovery.
Chiappetta (1997) tells us that “teaching science as inquiry stresses active
student learning and the importance of understanding a scientific topic.” There
are a variety of methods that can be used to increase the amount of inquiry
used in the classroom. Due to the wide variety of possible laboratory topics in
Biochemistry, problem-solving lends itself to a unit on biochemistry and would
also represent a more thought provoking approach to the lab experience.

Chiappetta (1997) states that:

"The problem-solving approach to scientific instruction should
not be forgotten because it has the potential to engage students
in authentic investigations and develop their inquiry skills. This
strategy can also make learning more meaningful and relevant
for teenagers.” (1997)

Broadening the scope of instructional techniques made it possible for me to
make Chemistry more relevant to my students thereby, engage more of them.
According to Osbume (1996), no one strategy in education is a panacea for all
students. Therefore, effective teachers must use a variety of instructional
approaches to reach the majority of students. Osbume (1996) also states that
educators should be concerned with employing more instructional techniques

to better meet the needs of our diverse students.

Over the years, I have found that chemistry classes have several different 'kinds’
of students. Some are easily engaged in the math portion of the class, and, in
my experience, these have been the majority. It is the minority, students who
typically favor English or History classes, that I want to reach and engage as
active Ieamers. Also, I expect to broaden the scope of all my students’ thinking
and problem-solving skills. I want them to incorporate other skills in their
Ieaming besides plugging in numbers and chugging out answers. All students
need to be both calculational learners of chemistry as well as conceptual
Ieamers. By learning material both ways, students will be able to make
connections they have missed in the past. According to Beall and Prescott,
“ideal conceptual Ieaming involves students identifying key concepts and
relating these concepts to ones already taught.” (1994) This is something that
the majority of my students cannot do well. One objective of my unit is to

increase conceptual thinking in all students.

i ntifi rvi - r nt inth r r r nt t dent
Advances in science have given us a fairly complete understanding of the
function of the molecules within our bodies. Over the years of human history,
many beliefs regarding the function of the human body were based on religious
traditions, myths and old wives tales. During the middle ages, bleeding was
often used to correct medical problems (Newton, 1986). As late as the early
1900's, medicinal leeches were being used to treat individuals with severe
colds and flus, as well as other ailments (Ceccarelli, 1998). Today, medicinal
leeches still have a role in medical science, where they are employed to
encourage circulation in body parts which were severed and reattached. By the
1600's, medicine became more of an observational science. Over the next
three hundred years, the approach to understanding life became increasingly
empirical. Since the 1930’s, scientists have begun to explore the human
organism in terms of chemistry and physics. Great advances in science,
particularly biology, have been made in the last sixty years. We have seen the '
genetic code cracked by Watson and Crick, as well as the relationship between

organelles and molecules within cells revealed. (Newton, 1986)

One area of science that has seen great advances is nutrition and identification
of the daily requirements of essential elements and minerals. The American
Association for the Advancement of Science report, Project 2061: Science for
All Americans (1990), recommends that all individuals should have a good
understanding of what is required to maintain life. This includes understanding
what trace elements are and their role in our bodies. Trace elements are
required by living organisms in small quantities. There are 19 essential trace

elements and ultra trace elements. These elements are used by the body for

growth and development and frequently they serve as cofactors in enzymes
(Lewis, 1992). From the chemical perspective, these elements come from all
parts of the periodic table. The role of each element in the body is related to it
chemical structure. To understand larger compounds, it is necessary to

understand the elements and functional groups they are made of.

Project 2061 also recommends that all Americans should be aware of the
molecules they are comprised of; and how cells carry out the various functions
utilizing proteins (1990). There are three major classes of biomolecules: 1.)
lipids, which include fats and oils, 2.) carbohydrates, which include sugars and
starches and 3.) proteins, which include enzymes, hormones, antibodies, and
structural elements of the body like tendons and cartilage. Each compound
can readily be identified in a secondary school setting. Fats are identified with
the brown paper test, which requires a small sample being wiped on a piece of
unglazed paper. Fatty substances will cause the paper to become translucent.

The Benedict’s test is a test for the presence of simple reducing sugars. In the
presence of a reducing sugar, a copper - ion complex is reduced to Cu+2. This

results in a color change from blue to orange to red to brown depending on the
amount of reducing sugar available (Meleca, et al. 1975). Complex
carbohydrates, like starch and glycogen, can be identified with the addition of
an iodine solution to a sample. A blue color is generated by the iodine being
bound to the larger carbohydrate molecules (Routh, 1979). Proteins can be
identified using two methods. The first method is the foam/lroth method. When
agitated, proteins will form a froth or foam on top (Nadler, 1996). The second
method is the Biuret test, in which a protein solution treated with Biurets’

reagent turns a purple/pink. The change in solution color, in a positive test, is

due to the formation of a complex between Cut”2 and a peptide with two or

more peptide linkages (Redina, 1971).

It is necessary to understand diffusion in order to understand activities
presented later in this unit. Diffusion is a rudimentary physical process in
chemistry and biology. It is the natural tendency of molecules to move from an
area of high concentration to an area of low concentration. A classic example of
this phenomenon is breaking a bottle of perfume in one comer of room. Before
long, all of the occupants of the room will be overwhelmed by the odor.

Diffusion can occur through air, liquids, and through an apparent solid, ie.,
gelatin (Brady and Holum, 1993 ). Several factors impact the rate of diffusion,
including temperature, the nature of the diffusion medium and the molecular

weight of the diffusing molecule (T zimopoulos et al., 1990).

Proteins are polymers of amino acids. Twenty different amino acids are
commonly incorporated into proteins found in living things. mause of the
number of different amino acids, there are a tremendous number of possible
arrangements and, thus, a tremendous number of possible proteins. All
enzymes are protein catalysts that work within cells to facilitate the chemical
reactions essential to life. They are crucial to organisms carrying out these
reactions at room or body temperature (Fox and Foster, 1957). Enzymes are
selective for their substrate, the reactant on which they work. Typically, there is
only one enzyme for each reaction and one or two substrates per enzyme.
Enzymes are not interchangeable between reactions. The active site, a small
part of the whole enzyme molecule, is the region that interacts with the

substrate(s) to facilitate the reaction. The rate of the enzyme catalyzed reaction

is affected by: 1.) concentration of enzyme, 2.) concentration of substrate, 3.)

temperature, 4.) pH and 5.) salinity (Stryer, 1981).

W
In 1997-98, one section of chemistry was offered with 25 students enrolled in

the second semester. Chemistry is a yearlong class. During the research
period, April and May of 1998, the number of students dropped from 25 to 24
due to the incarceration of a student. 32% of the students were female and
68% of the students were male. 96% of the students were Caucasian and 4%

were Asian/Pacific Islander. This class is a fair representation of the community.

The district services a community of over 15,000 citizens. The median income
of the community is $34,468. The community is 96% Caucasian, 0.1% black,
1.2% Asian or Pacific Islander, 0.2% American Indian, Aleut, Eskimo and 2.1%
Hispanic. This high school is the only high school within the district. It serves
651 students with a staff of 30. Despite these small numbers, there are a variety
of educational opportunities. All students at this high school must successfully
complete one year of Physical science in the ninth grade in order to take the
other required course, Biology. Students planning on attending post-secondary
training or college are encouraged to take at least 2 science electives,
Chemistry and Advanced Biology or Physics. To enroll in chemistry, students
must have completed algebra with a “C” or better, a "B" or better in Biology and
the recommendation of a science instructor. Chemistry is offered every year
with an average enrollment of 25 students per section. (Annapolis High School
Student Profile, 1998)

 

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IMPLEMENTATION OF THE UNIT

The biochemistry unit was designed to address the following concerns:

1. A lack of relevance in the science curriculum
2. A lack of integrated science in the curriculum
3. A lack of participation in inquiry based labs

I wanted to have students participate in a lab driven class, where assessment
was more closely tied to lab work than in the past. It was my expectation that
students would be better prepared for college after completing the class and
participating in this biochemistry unit. To evaluate the effectiveness of my unit, I

used a new instructional technique by including a hands-on assessment.

The unit, taught immediately following a small unit on oxidation - reduction
chemistry, is approximately eight weeks in duration. Following the
biochemistry unit, students studied acid/base chemistry. The unit represents a
completely new topic in the curriculum (the complete curriculum is located in
Appendix A). Prior to the unit’s inclusion, biochemistry was only addressed in a
cursory manner in the ninth grade. One of the unit objectives was to make the
entire course more interdisciplinary by linking chemistry to other scientific
disciplines. Prior to beginning the unit, students and their parents were notified
of their participation in this study with a letter (Appendix 8). Also, student prior
knowledge was assessed with a pretest. The pretest was not part of the
extensive formal analysis of the unit but was used only to find out what students

knew coming into the unit.

 

 

 

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Objectlves and Student Actlvltles
By studying lipids, carbohydrates and proteins, students will:

Oneal—Wes
1. Identify the elements commonly found in biochemical compounds.

2. Recognize the organic functional groups found in each of the three classes
of biochemical compounds.

3. Understand the relationship between the terms monomer and polymer in
the context of the three classes of biochemical compounds.

4. Identify the unique features and characteristics of biochemical compounds
studied. Identify their roles in our bodies and where they are commonly
found.

5. Perform the identifying tests for each of the three biochemical classes of
compounds. Be able to identify an unknown compound and justify their
conclusion.

6. Explain the chemistry of the Benedicts Qualitative Solution test for reducing
sugars and the iodine test for starch. Connect this to redox chemistry.

By exploring the factors which influence diffusion rates, students will:

1. Explain what diffusion is and its significance in Biological and Chemical
systems.

2. Identify factors which influence the rate of diffusion.
3. Graph the distance compounds diffused using a best fit line.
4. Interpolate to estimate the molecular weight of an unknown organic dye.

5. Evaluate the accuracy of the best fit line with an error analysis of
calculations.

By exploring the nature of enzymes, students will:
1. Explain what the chemical and biological nature of an enzyme is. Students

will be able to provide at least one example of an enzyme catalyzed
reaction.

10

 

 

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2. Identify factors which influence enzyme behavior by exploring the effect of
enzyme concentration and substrate concentration on enzyme reactions.

3. Explain what a substrate is and its relationship to the active site, as well as
the role of the active site.

4. Examine the affinity of an enzyme for a substrate by offering one enzyme
two different substrates.

5. Explain why enzymes are needed to assist in the diffusion of most molecules
through a selectively permeable membrane.

The majority of activities that students are involved in are inquiry lab
experiences, in which students learn a procedure and then apply it to a new
situation. Additional experiences include:

1. A reading on trace minerals. Students will discuss their importance to
their health and well being.

2. Observe the construction of biochemical macromolecular (ie., a polypeptide,
a carbohydrate and a lipid molecule) models and discuss how their

structure is related to their function.

3. Make and use graphs with best fit lines to interpolate information.

All of these activities represent new activities that were developed for this unit.

Outline of Unit

Week 1

Biochemistry pretest.
Article reading, “Essential to Health: Trace Elements” (Lewis, 1992).
What is the role of chemistry in the living organism?

Video: The Wgrlg Qf Qhemigry - Carmn.
Week 2

Readings from chapter 23 (Tzimopoulos, 1990).
Observe the construction of macromolecular models.
Students construct macromolecule models of proteins and carbohydrates.

11

Discussion of characteristics/functions of lipids, carbohydrates and proteins.

Week 3

Laboratory practice and techniques for identifying biomolecules.
Do lab cluster Whet ie it? Which includes testing for simple carbohydrates,
complex carbohydrates, proteins (using two tests) and lipids.

Wfik 4

First major evaluation - laboratory assessment - Identify unknown samples.
Write report on unknowns.

Diffusion demonstration - launches discussion of diffusion.

Hypothesize on the effect of molecular weight on the rate of diffusion.

Do the model ouchterlony to test hypothesis.

Week 5

Do diffusion lab to find the molecular weight of an unknown dye.

Analyze data with best fit lines and determine the molecular weight of the
unknown.

Do an error analysis of the interpolated data.

Discussion of the role of diffusion in living systems.

Week 5
Video: The Werlg of Chemigm - Preteine: Structure eng Fenctien.

Begin to explore enzymes.

Practice filter disk procedure for enzyme labs.

Enzyme activity lab exploring the effect of catalase concentration and peroxide
concentration.

Examine and graph data.

Week 7

Explore enzyme specificity.

Demonstration of a cell system with dialysis tubing as a spring board for
discussion on the role of enzymes within living systems and how this
relates to diffusion.

Test substrate preferences of an enzyme.

ka 8
Second major evaluation - objective and essay test.

12

Audio Visual Aide

I used two videos in the teaching of this unit. The use of videos represents the
addition of another instructional strategy. The first video used was The World of
Qhemigm: QeMn. This video provides a review of the characteristics of
carbon and the variety of carbon compounds in our world. This video was used
to introduce the unit and served as an opening for a discussion on
biomolecules. lt reviews much of the material on carbon and basic biochemistry
covered in our ninth grade Physical Science class. Essentially, it is a good

review of the concepts that should be a part of students’ prior knowledge.

The second video shown was also from the series The Werld ef Qhemigry
entitled Preteine: Structure eng anetien. This video was used to introduce
enzymes and show the amazing variety of protein structures possible. It served
as a springboard for a discussion on the importance of proteins, biologically,

chemically and technologically.

Implementation and Analysis of Student Activities and Laboratory
Exercises

In all of the following activities, students worked with the same group of
individuals. Generally, groups had three or four members randomly assigned to
them. Groups learned a specific test or procedure in each lab experience. The
inquiry nature of these activities was the application of the newly learned
knowledge to a new problem. The laboratory experiences were divided into
three major clusters: 1. What is it - the identification of biochemical compounds,
2. Diffusion - the study of diffusion and the factors that affect it, and 3. Exploring

Enzymes - an exploration of various aspects of enzyme behavior. The unit was

13

designed to be sequential to ensure students had the prior knowledge needed

for success.

Artiele Reeeing

One of the activities I incorporated into this unit was the analysis of the article
“Essential to Health - Trace Elements” (Lewis, 1992). The article discusses the
role of chemical elements in the body. It provides relevance for students by
addressing nutritional needs of individuals. Also, the article served as an
introduction to the chemistry of the body. Students read the article and
responded to questions from the article. This served as a spring board for a
discussion about the role of elements in our daily health. Students were
engaged by the article. Of particular interest to them was the discussion of pica,
the psychological phenomenon where people eat odd things like dirt and clay.
This article also launched a discussion on the role of chemicals in our
environment. Students discussed how toxins can be absorbed from the
environment. Of particular interest was how easy it was for lead poisoning to
occur. Students were amazed to discover that too much or too little of trace
element could be a serious problem. Student analysis of the article was
evaluated by reading and scoring student responses to questions based on the
article.

M l ilin -A nixD

In the model building demonstration, students observed the flexibility of long
chain lipids. Students observed the construction of models of two large lipid
molecules, palmitic acid and oleic acid. Students were asked to make

observations on the flexibility of the two molecules. Students were also asked

14

to recall, from Biology class, what the fluid mosaic model of the cell membrane
was and what was meant by the term lipid bilayer. Students made the
appropriate connection between the two terms and began to develop an
understanding of why lipids are a good molecule for membranes.

The second half of this activity asked students to construct models of
monosaccharides, individually, and then, joining with other groups, to create
larger carbohydrates. Students developed an appreciation of the
monosaccharide as a monomer of the larger complex carbohydrate polymer.
The same process was repeated for amino acids in the construction of larger
polypeptides. Students developed an appreciation for the size and complexity
of these molecules. Also, students were able to visualize condensation
reactions and understand where the atoms making up the water molecule,
which is generated, originate from. In the ‘hydrolysis’ of their large polymers,
students could visualize the fate of a water molecule. The use of models was
apparently effective in visually demonstrating the relative size and shape of
these molecules, as well as showing were these reactions occurred. By the end
of the activity, students seem to be able to make connections to prior
experiences. Unfortunately, this activity is not structured enough and needs to
be modified to encourage long term retention of concepts covered. (see

Evaluation)

Whet is it? - Apgngix E

What is it? is a collection of lab explorations in which students learn to use the
following tests: 1.) The Benedicts test to identify reducing sugars, 2.) the iodine
test to identify complex carbohydrates (starch and glycogen), 3.) the brown
paper test to identify fats, 4.) the Biuret test to identify protein, and 5.) the

15

foam/froth test to identify proteins. The chemistry of the tests was explained to
students prior to each experience. Also, students were asked to consider the
environmental impact of the waste generated from the lab procedures. With
each test, students were expected to establish what was a positive test and a
negative result. In each experience, students were expected to follow proper
experimental procedures and establish a control. In the analysis section of
each activity, students were expected to answer questions which took
information established in the lab experience and apply it to real-world

scenanos.

Initially, some students were overwhelmed by the change from a more
traditional classroom to a more inquiry based one. They had difficulty following
the most basic instructions. It became apparent that they were suffering more
from the “fish out of water” syndrome than anything else. As the number of days
where students were involved in lab increased, they became more comfortable
and productive with this format. I was impressed with the development of their
group and lab skills. Also, the nature of their questions was changed. Two
students came in regularly on their own time to continue discussions begun
during class. A third of the class expressed a pleasure with the increased

relevance of the material.

The What Is It? portion of the unit was evaluated by providing each student with
an unknown sample and develop and implement a procedure to identify it.
Unknowns were selected from the compounds students had been testing the
week before. When developing their procedure, students were told to keep in

mind the cost of materials and the potential generation of hazardous waste. It

16

was my intent that students would realize that it made more sense to do the
foam/froth test than the Biuret test to identify proteins. Also, it would be better to
begin with environmentally friendly tests like the brown paper test and the

foam/froth test.

This assessment was given an everyday flav0r by the final task, writing a letter
to their ‘supervisor'. They had to explain their decisions, based on the outcome
of the procedure, in terms of cost-effectiveness and limiting the reduction of
hazardous waste. This assignment was a new type of assessment for me. It is
very hands-on and engages each student in the process of science, which was
the goal. It was a pleasure to read the student letters. Many students enjoyed
their test of this portion of the unit. This is not something I frequently hear about
a test. Some students spent a great deal of time composing their letters and

showed a great deal of creativity.

Diffusjen - Apmneix F

The diffusion labs were designed to allow students to discover the effect of
molecular weight on the rate of diffusion. Prior to beginning the labs, students
engaged in a teacher-directed discussion of what factors impact diffusion. It
was an open discussion of ideas without ‘the answers' being provided. Prior to
beginning this model Ouchterlony activity, the lab groups worked together to
formulate a hypothesis about the relationship between molecular weight and
the rate of diffusion. Students then prepared their diffusion plates, noted the
time they filled the wells and waited for a precipitation reaction to occur. Using
the time it took the contents each well to react with the contents of the central

well, students reassessed their hypothesis. By posing questions to individual

17

groups, it was apparent that students had a good grasp of the relationship

between molecular weight and the rate of diffusion.

Before beginning the second experiment, the class discussed using the rate of
diffusion to determine the molecular weight of an unknown compound using the
same set up. Students were advised that at least one member of each group
would have to come in later that day to make measurements. This activity takes
at least 2 hours to complete, at the end of this time, one student from each group

returned and measured how far the contents of each well had diffused.

Data were collected during the first day of this experiment. Analysis of the data
occurred over the next two class periods. On the second and third day,
students graphed their data using the best fit line technique. Unfortunately, no
computer lab is available for analysis using a spread sheet program. Despite
this, students mastered the notion of the best fit, and understood why it is better
than 'connecting the dots”. Finally, students interpolated the molecular weight
of their unknowns and compared them to the actual molecular weights.
Students determined their percentage of error and many were amazed at their
accuracy. This was a launching point for a class discussion on how scientists
can discover characteristics of a compound and the problems that could be
encountered. Students considered sources of error in the experimental process
when they were done. Students were astute and made some interesting
comments on why molecules do not always behave as expected. Some
members of the class suggested that one smaller dye, that should have moved
faster, may have been attracted to the medium. I was impreSsed their insight

into the many factors involved. This suggested growth in the thinking processes

18

of the students, which was one of the goals of this unit.

Assessment of this group of activities was done by examining student
responses to questions, the percent error and student explanations of error, and

specific questions from the biochemistry unit test.

Ex lorin Enz e - A ndix

Exploring Enzymes represents the last cluster of lab activities in this unit. The
first enzyme activity explored the effect of enzyme (in this case catalase)
concentration on enzyme activity. The other half of this first activity was an
exploration of the effect of substrate concentration (peroxide) on the activity of
the enzyme. Because of the complex nature of this procedure, students were
given a day to practice. This made the actual testing of the variables much
more accurate and students were able to focus on the science and not the
procedure. Results of these investigations were very supportive of the class
hypothesis that enzyme activity would decrease with a decreasing
concentration of enzyme as well as with decreasing substrate. The activity of
the enzyme was calculated from the averaged data and plotted as a best fit line.
Assessment of this group of activities was done by examining the graphs and by

specific questions from the biochemistry unit test.

The last set of activities incorporated both a demonstration and a laboratory
exercise. In the demonstration, The Substrate Preferences of Sucrase,
students observed four model cells, made from dialysis tubing, filled with
enzyme, sucrase, and in each model, a different substrate. Students were

reminded that dialysis tubing is a selectively permeable membrane that glucose

19

could diffuse through. However, none of the substrates could diffuse through
the tubing. After 40 minutes, samples from outside each tube were collected
and tested with Benedicts reagent. Only one model revealed that glucose was
present. This demonstrated: 1. that sucrase breaks something down into

glucose, and 2. that sucrase is specific about what it will react with.

In the activity, The Preferences of Amylase, students compared the action of
amylase and sucrase on one substrate. Benedicts reagent was used to show
which enzyme - substrate mixture reacted. If the correct substrate was provided
to amylase, a reducing sugar was produced. Overall, students had more
difficulty with activities related to enzymes. Despite this, their responses to
enzyme questions on the final unit test were, typically, correct more than 75% of
the time. Assessment of these two activities occurred through student responses
to questions at the end of the activities and items on the final unit test, both the

objective and essay portion.

20

RESULTS AND DISCUSSION

The Biochemistry unit was evaluated using student lab scores and student
scores on tests. Specifically, the laboratory assessment was based on three
different lab clusters which involved multiple activities as discussed in the
previous section. Students were also evaluated by two tests. The first was a
lab practical where students identified an unknown biochemical compound.

The unit test was an objective test taken at the end of the unit.

111 fth Bl h mlt Unit Pret t
Complete results of the Pretest are available in Appendix C. The pretest was
designed to assess the prior knowledge of my students. The majority of
students in the class share a common science class background and it was

anticipated that the majority would be familiar with several concepts.

Responses to the first question were surprising and disappointing. Despite an
introduction to the three major classes of biological compounds, none of the
students correctly responded to this question, and 30% did not even respond.

10% of students did not know what a good source of protein would be in food.

As expected, the majority of students did not really know what trace minerals
were or what elements were trace elements. Only 50% of the students
responded to question three, which asked students to explain what trace
elements were. Despite not knowing, they did make good educated guesses
when they did guess. More students responded to question four: 90%

realized that iron is an element essential to life and 95% realized the same

21

about oxygen. While all students agreed that there was a relationship between
biology and chemistry, in question five, 45% stated that the relationship
“involved the existence of life” and only 5% clarified with the statement “that

cells do chemistry to survive“.(Appendix C)

In question six, a scenario involving diffusion, 60% of students correctly
described what happens without using the term diffusion and the remaining
40% utilized the term diffusion. When a similar scenario was provided, in
question seven, that prompted students for more in-depth answers, interesting
facts were revealed. While students were aware of diffusion, they had difficulty
applying it to a new medium. For example, diffusion in the air was obvious to all
students; but, when water was involved, students were not as confident. 15%

of students could not recognize diffusion occurring in water.

Answers to the last two questions showed that students were aware that there
were optimal conditions for life, but they were not clear on what they were. This
question needs to be restructured to elicit more specific answers. The last
question indicated that students were not really sure what enzymes did. Of the
students responding, less than 50% realized that enzymes catalyze reactions.
In light of the fact the concept is covered in the ninth and tenth grade science

classes, this is disappointing.
These topics were all addressed in the required lab explorations and reading

assignments. The pretest items were assessed again in both the hands-on test
and objective unit test.

22

Table one is a summary which shows the number of points possible on each

laboratory cluster, the range of scores, the average score, the percent average

and the standard deviation.

Table 1

Data table of lab activity scores and statistical information from the Biochemistry

points

Dosing
What Is It? 80.0
Diffusion 40.0

Exploring Enzymes 60.0

What Is It?

Evaluation 100.0
Objective

Unit Test 150.0

Unit.

mes
58-80

33-40

20-60

80- 110

78- 150

meen
75.3

38.1

51.1

93.5

118.8

percent
me

94%

95%

85%

94%

79%

standard

gevietien
5.3

1.9

10.8

7.3

18.5

An evaluation of the two tests (What Is It? Evaluation and the Objective unit test)

also is presented with relevant statistics for the two assessments are included

on table one. In the discussion of each activity, relevant statistics.

23

The following section presents the rubrics for the assessment of the three lab

clusters.

Whg I; It?
Evelgetien fermet:

. , l' i
Data table and results

Responses to Analysis Questions

W

Data table and results

Responses to Analysis Questions

mam
Data table and results

Responses to Analysis Questions

The Eat Tee
Data table and results

Responses to Analysis Questions

2W

8 points

12mm:
20 points possible

5 points

15.311113
20 points possible

12 points

int
20 points possible

12 points

int
W
80 total points possible

The range of scores for this cluster of labs is 58 - 80, which corresponds to 22

points. The raw mean score on this cluster of lab activities was 75.3 points,

which is equivalent to approximately 94%. The standard deviation is 3.9. (I’ able

1) The distribution of student scores can be seen in Figure 1. The majority of

students are clustered above the mean. There are a few individuals below -1

standard deviation. The wide range of scores, at the low end, is due to two

24

students. One student missed a day and never came in to make up the lab. The
other student simply refused to do the work and accepted a zero on 40 of the
available points. Subsequently, this student went on to fail the entire semester
by not completing key assignments. The data were analyzed with the lowest
score being dropped because it was an extreme outlier of the data set (n=24),

dropping the standard deviation from 10.1 to 5.3.

For many students, this week represented the first week they had ever devoted
entirely to lab exercises in a science class. Observing them, it was apparent
that they initially were uncomfortable in the lab setting. As the week
progressed, they became more comfortable and at ease with what they were
doing. Many students remarked that they were having fun. Several commented
that they would prefer to do this more often. The informal class consensus was
that science made more sense when approached this way. Most notable were
the comments of one particular student who had struggled the entire year. He
repeatedly commented on how much he enjoyed doing this and how it made so

much more sense to him.

25

Figure 1

 

 

 

8571
l
o e e e 00
e e
O O O O O
O O. O
75- ’
O
0
g, e
e
3 7o-
3
a
a:
65-
O
60-
O
55 TtrriiiiiiiTtTTiirTTTTT11
13 5 7 91113151719212325
Student Number

 

 

0 student scores
mean
------ +1 SD
------- 1 SD

 

 

Figure 1. A scatter plot of the distribution of student scores on the

laboratory cluster What Is It?

26

 

The Identification of the Unknown was an assessment that provided students
with the opportunity to apply all they had leamed to a new problem. It
represents a new form of assessment for my classroom, one that is completely

inquiry based.

Evelgetien ef Whg lg If?: the gentiflcfilen ef the flnknewn

Evelgetien Fermet: Peinte eeeigneg:
Creation of procedure, data table 40 points

and presentation of results. This
includes logical sequencing
of experimental tests.

Correct identification of unknown. 30 points
This includes justification of

identification utilizing experimental

results.

Letter to Supervisor. This includes 30 points
a clear and concise report detailing

what was done and why. Students

are expected to justify all decisions

and use correct grammar and spelling.

Extra sample - 5 points each occurrence

Being environmentally friendly and + maximum of 10 points based on
cost effective. th in ructors i r ti n
100 total points possible with 10
bonus points available.

Student scores ranged from 0 to 110. One individual received a zero as a result
of a conscious choice to not do the assignment. Since this score was an
extreme outlier in the data set, the individual’s score was dropped (n=24). The
range of scores without this individual is 80 - 110. The mean raw score of all

the scores is 93.5 points, approximately 94%. The standard deviation is 7.3.

27

(Table 1) As is indicated in Figure 2, there is a good distribution of scores

above and below the mean. There are two scores below -1 standard deviation

and 4 scores above +1 standard deviation.

Many students enjoyed this evaluation. It is probably the first time in the year

that students enjoyed participating in their assessment. Several students

remarked that it was fun and wished more of their assessments could be

structured this way.

The following is the scoring rubric and analysis of the lab cluster Diffusion. This

lab cluster involved students applying their prior knowledge of diffusion to new

scenarios. It also provided a review of concepts that students needed to

understand future activities.

lef I n
Evelgetien fermet:
iff ' r' n

Hypothesis regarding relationship
between molecular weight and
diffusion.

Determination of molecular weights
with rate predictions.

Data table with results

Responses to analysis questions

4 points

4 points

4 points

3%
20 points possible

28

Figure 2

1151
110-: e
1053 e 90

95 40 e e e

 

90~ O. 0000 O. O O 0

Raw score

80 T. O

751

 

 

7O Tli'iiTTTlTliiTT-71T7Tlliiil

13 5 7 91113151719212325
Student number

 

 

9 student scores
mean
------ +1 SD
------- 1 SD

 

 

Figure 2. A scatter plot of the distribution of student scores on the

hands - on assessment of What Is It?

29

 

EII' E . HE

Data table with results 2 points
Graphical representation of data 8 points
Response to analysis #1 5 points
Response to analysis #2 2 points
Response to analysis #3 int

20 points possible

The range of scores for Diffusion is 33 - 40. Low totals were due to failure of
several students to turn in one of the two parts of this lab cluster. The mean raw
score is 38.1, which represents a percentage score of approximately 95%. The
standard deviation is 1.9. (Table 1) Figure 3, shows a good distribution of
scores within the range of + or - 1 standard deviation. For this analysis, n=23,
two students were eliminated from the analysis because of their complete lack

of participation.

30

Figure 3

 

 

 

 

42-
40 A -e--"Hue--"no-moneeueeeu-
38+ 1 W to
g e
”361 e 00 e ' 6 '
B
a
a:
341
e
32-
3O lilFllTTlTjTTTTflllTTlll
13 5 7 91113151719212325
Student number

 

 

0 student scores
mean
------ +1 SD
------- 1 SD

 

 

Figure 3. A scatter plot of the distribution of student scores on the

lab cluster Diffusion.

31

 

Informal student response to this group of activities was positive. Students were
impressed with their accuracy in determining the molecular weight of an
unknown substance. Many students were enthusiastic about doing the many
lab activities and the time spent with each one. The consensus of the class was
that they had a better grasp of diffusion because the content was explored more

completely at a relaxed pace.

The following is a scoring rubric and analysis of the lab cluster Exploring
Enzymes. Students were provided with the information needed to assess

various factors impacting enzyme function. Students were then allowed to

investigate these factors.

Exelerlng Enzymee

Evelgetien fermet: W
W

Data table and results 5 points
Graphical presentation of data 10 points

Written analysis of graphs and the int
relationships presented. 20 points possible

Ho _oiaifi Ar 11 _m-___Th- . r--Pr-f-r-_n - of ,. .~

Observations - recorded with 10 points
conclusions on data table

Responses to analysis questions 19 minte
20 points possible

32

:T ifii fAml

Data table with results 5 points
Responses to analysis questions 15 eeints
int i l

60 total points possible
The range of scores for Exploring Enzymes is 20 - 60. Again, two students did
not turn in any portion of these labs. One student was not able to participate for
the remainder of the semester as he was incarcerated. The other student was
suspended during the trial period and made no effort to make up the
assignments, despite being provided many opportunities. Both of these
students represent extreme outliers and were dropped from the data set. (n=23)
Five students only turned in 2 out of 3 activities. It is possible that students were
becoming lazy or overwhelmed as they approached the end of the semester.
The mean raw score was 51.1 points, or approximately 85%. The standard
deviation is 10.8. (Table 1) Figure 4, visualizes the wide range of scores.
Again, the majority of scores are clustered above the mean. There are five

individuals that have scores below -1 SD, four of which are well below this

point.

33

Figure 4

65-

601 O O
0.. O O O
55* 00 e

50*
451

40

Raw Score

35- e ..
30-
25-

20- e

 

 

15 IITTTITITTTT-fiiiiITIITTTTj

13 5 7 91113151719212325
Student number

 

 

9 student scores
mean
------ +1 SD
------- 1 SD

 

 

Figure 4. A scatter plot of the distribution of student scores on the

lab cluster Exploring Enzymes.

34

 

I observed that those students that actively participated in all aspects of the
enzyme labs enjoyed the assignments. However, of all the labs, those involving
enzymes seemed the most difficult for students to comprehend. To improve
them, I plan on narrowing the focus and increasing the time spent introducing
the concepts behind the labs. At this point in the unit, several students said they

were tired of doing labs and wanted to ‘get back to the Math’.

Anal l f udent P rt rm nce on b Iv nit T t

A copy of the objective unit test can be found in Appendix H. Student data were
analyzed by eliminating the zero assigned to the incarcerated student. There
was a range of scores of 78 to 150, with a raw mean score of 118.8 or
approximately 79%. The standard deviation is 18.5. Figure 5, shows the
distribution of all the scores. It reveals that the scores are predominately within
the range of + or - 1 standard deviation of the mean. Overall, student
performance on the test was reasonable. I think that if the unit was trimmed

down and modified slightly, scores would be better.

35

Raw score

Figure 5

160-
150- 0
140 ’

130 1

 

l
. . 1 0 student scores

 

120 fl 9 mean
0 ------ +1 SD

O
110- o '0 """" ‘30

 

 

 

1oo-;~----’""----""""""""""-
90-
so—

701

 

 

60 iiitTFTfiTfiTrTiffifitiritrrn

13 5 7 91113151719212325
Student number

Figure 5. A scatter plot of the distribution of student scores on
the unit objective test.

36

The source material for the questions on the objective portion of this test were
the laboratory experiences and the textbook and other reading selections
coupled with lecture. There were 35 objective questions, 25 or 70% derived
from the laboratory experience and 10 or 30% based on lecture or textbook or
other reading selections. When analyzed, 8/25 or 32% of the lab based
questions were missed by at least 50% of the students. A similar analysis of the
lecture based questions revealed that 2/10 or 20% was missed by more than
half of the students. Examination by topic revealed that the majority of
questions missed followed no specific pattern. There was one minor trend
which suggested that questions related to the modeling lab were missed more
frequently than others. Specifically, 3/6 or 50% of the questions which had
been reinforced by the modeling lab were missed by a minimum of 50% of the
students. Recalling that the modeling lab was the first lab and the most open
ended, it follows that the modeling experience needs to be more structured and

less inquiry driven.

marlnfu enth Ob Ithan thL cr
Figure 6, represents a correlation and regression graph of the total scores for all
lab activities in the unit and the assessment of the entire unit. There is a
positive linear correlation between the two sets of data with r equal to 0.28,
suggesting that the two sets of data are slightly dependent on one another The
trend suggested by the data is that success on the lab activities does not

necessarily mean that the student will be successful on the objective test.

37

Obective unit test scores

160 1

150 s

140 —

130 1

120 -

110-

100 4

90-

 

80

Figure 6

 

 

 

 

e
O
.0
O
, e e
O
9 student scores
” —regression line
0
0
° 0
O
O
O
o
0
$

y = 0.2501x + 30.035
R2 = 0.0776

 

80

l T T T l i

1 00 1 20 140 1 60 1 80 200
Lab scores

Figure 6. A regression between student performance on all of the
laboratory assignments and performance on the objective unit test.

38

C m arl n f u n th Lab Evaluation and Ob ective Test
Figure 7, represents a correlation and regression graph of the hands-on lab
evaluation and the objective unit test. With only a slight positive linear
correlation present and r equal to .02, the data suggest that some students may
not have performed as well on the objective test as they did on the hands - on
evaluation. This is not surprising. Students worked for a solid week on learning
all aspects of the identifying tests and then had two class periods and additional
time after school to complete the hands on assessment. The unit test occurred
at the end of seven weeks of material and was the last major test of the
semester. Student motivation was not high for the unit test. The average score
on the hands - on assessment was 94% and for the objective test it was 79%.
While there is no correlation between these two tests, the average scores do
lend support to the notion that a more hands-on approach to assessment

provides more opportunity for more types of students to be successful.

39

Figure 7

 

 

 

 

 

 

 

 

 

160 1
150 - e
O
140 4 . ,
3 l 3 . ’
§ 130 4 °
3' ' .
2’. l d t
g 120 1 f e stu en scores
3 — regressmn line
.1, e
E. ’ o
g 110 - e e
3 e
O : .
100 1 ° ,
| . .
90 _ y = 0.0501x + 115.83
R2 = 0.0005
80 T i - i
75 85 95 105 115

Hands on assessment scores

Figure 7. A regression between student performance on the hands - on
assessment and the objective unit test.

40

CONCLUSION

In terms of success on labs and tests, the biochemistry unit was successful in
making chemistry more relevant for my students, demonstrating the
interdisciplinary nature of science and expanding the thinking skills of my
students. It provided my students with the opportunity to explore science
through inquiry style laboratory experiences. Changing the format of the
laboratory experience was important since the majority of my students had only
previously experienced verification style labs. Overall, it was a positive change

for my students. They found lab to be both fun and thought provoking.

The results of student scores on the inquiry based labs, the hands - on
assessment and the objective unit test demonstrated that using an inquiry
based environment which is interdisciplinary in nature was a success. The
average scores on the three lab inquiry clusters were 92%, 92% and 85%.
While all three lab clusters followed the inquiry style, I believe there are several
reasons why students did not do as well on Exploring Enzymes . First, it was
the last major topic of the semester to be taught. Secondly, students, according
to the analysis of'the Pretest (Appendix C), had more prior knowledge of the first
two topics. Finally, the enzyme labs need to be modified to better meet the
needs of students. Specifically, the instructions need to be clarified. The
inquiry style assessment had an average score of 89.8%, while the objective
unit test, given at the end of the seven weeks, had an average score of 79%.
This is slightly lower than the average for other unit tests given during the year.
The inquiry assessment followed an introduction to biomolecules from an

interdisciplinary lecture/discussion format and a week of inquiry labs. This

41

supports utilizing a wider variety of instructional techniques and creating more
innovative assessments. There are several possible reasons for the lower
score on the objective test. First, the a lot of material was covered on the test .
Second, the test was a traditional objective test that did not reflect the inquiry

nature of the unit. Instead, it represented a return to traditional assessments.

There are several things I will change the next time I teach this unit. First and
foremost, the enzyme labs will be modified to be more student friendly. I will
reduce the number of concepts introduced simultaneously and restrict it to one
idea - one day approach, increasing the time involved in the instruction of
enzymes. Also, I will include a more structured procedure practice day.
Measuring enzyme activity can be difficult the first few times. Beginning from a

more structured perspective allows students to become more creative.

The modeling lab, which was open ended and observational in nature, also will
become more structured for students. In addition, it will become a
demonstration, to utilize less class time. Thought provoking questions will be
used to prompt students to think about the molecules correctly. Questioning will
be step wise, to aid students in their thinking and to assist them in reaching the

correct conclusions regarding the molecules they are observing.

The reference reading materials from the textbook are, to say the least, not
wonderful. Additional support reading will be found. Study guides, done at
home, to accompany the new reading selections will be developed. The
readings from the textbook used during the testing period will not be used

again.

42

I will also change the unit test to be more inquiry based, like the more
successful hands - on assessment. The objective questions will be structured
differently, to reflect an everyday flavor. More constructed response questions
will be used. Also, questions that the majority of students did not answer
correctly indicate that the questions were flawed in their design or the material
was not covered adequately or a combination of the two. An analysis of the

responses to questions will be used to restructure parts of labs and activities.

Overall, the biochemistry unit was a success. Most importantly, students
experienced an inquiry based classroom. I am motivated to develop more labs
in other areas to be more inquiry in nature, without forgoing with all of the
structure. I have developed a better understanding of how students learn and
what is successful in teaching them and what is not. If students can walk away
from this semester with a better understanding of the process of science and
how it impacts their daily life, then this unit was truly successful. The most
important lesson of this unit for the instructor is that we are all, truly, life-long

learners.

43

Appendices

44

Appendix A
Course Title: Chemistry
Course Description:
The material covered in Chemistry includes a study of the atom and its structure,
the elements and their properties, the mechanisms of formation of compounds,
including organic compounds, and investigations into properties of solids,
liquids and gases. The student is provided with the opportunity to observe and
investigate various chemical reactions and develop proper laboratory
techniques necessary for future classes. It is designed for the students who
plan on attending a four year college.
Goals and Objectives:
To become knowledgeable of laboratory safety rules and procedures. To gain
an understanding of:
1. Measurement in Chemistry.
2. Matter and its changes.
3. Atomic structure.
4. Arrangements of electrons in atoms.
5. The periodic law.
6. Chemical Bonds.
7. Chemical Composition.
8. Equations and mass relations.
9. The molecular composition of gases and the gas laws.
10. Solutions.

11. Ionization.

12. Acids, bases and salts and pH.

45

Classroom Materials:

Text: Water

Evaluation:

Students evaluation will be based on performance on lab, quiz, test and
notebook.

Outline:

Chapter 1
Matter and Energy
Classification of Matter
The elements
1 week

Chapter 2
SI math
units
conversions
accuracy/precision
solving problems
2 weeks

Chapter 3
The atom
Dalton
The structure of the atom
Atomic number
the mole
problem solving
2.5 weeks

Chapter 4

The atomic model

changes to the model
Quantum Theory

quantum numbers

energy levels
Electron configurations

2 weeks

46

Chapter 5

The periodic table
Mendeleev
discovery
periodic law
periodic properties
electron configurations and blocks

1.5 weeks

Chapter 6
Chemical bonding
ionic
covalent
Lewis structures
Properties of ionic/covalent compounds
3 weeks

Chapter 7

Ions

binary compounds

acids

Oxidation numbers
patterns
determining

Formula mass

Empirical formula

molecular formula

percent composition

5 weeks

Chapter 8
Classifying reactions
Balancing reactions
predicting reactions/no reaction
predicting products
2 weeks

End of Semester 1

Chapter 9
Stoichiometry
mole - mole
mass - mole
mole - mass

47

Chapter 9
mass - mass
limiting reagent
theoretical yield
4 weeks

Chapter 1 1112
Kinetic theory of gases
real vs. ideal
Qualitative descriptions
Quantitative descriptions
ideal gas law
Grahams law of diffusion
stoichiometry of gases
3 weeks

Chapter 14
solutions
types
concentration
Molarity
the solution process
3 weeks

Chapter 15
Ions in solution
properties of electrolytes
1 week

Chapter 16
Acids/bases
properties
reactions
names
Reactions between acids and bases
neutralization

1.5 weeks
Chapter 17
Calculating pH
pH scale
Normality and molarity for acids and bases
1.5 weeks

48

Chapter 23
The chemistry of life
biomolecules
fats
carbohydrates
proteins
Qualitative description of an unknown
Trace elements
Enzymes
Quantitative description of enzyme action
specificity
6 weeks

49

Appendix B

Dear Parent:

Your son/daughter is a member of my Chemistry class. During this year, I will
be teaching a model unit. This teaching unit will enrich our Chemistry program
and better prepare your student for the future. I will be using this unit as a core
portion of my Master’s thesis. I am writing to request permission to use your
students scores and other measures of performance anonymously as an
evaluation of this unit for my thesis. Choosing to participate or not participate
will not affect your son/daughters grade. Please fill out the bottom portion of
this letter and return it to me with your student. If you have any questions,
please feel free to contact me at 313-278-9870.

Thank you,

Sara Dallas

 

I, . give my permission for the scores
of

 

to be used anonymously by Mrs. Dallas in her thesis. I

 

understand that choosing to participate or not participate will have NO effect on

my son/daughters grade.

 

 

parent/guardian signature date

 

 

student signature date

50

Appendix C
Pretest Name:
Directions: Answer each of the following questions to the best of your ability.
The object of this exercise is to see what you already know. It is not a graded
assignment. You are expected to draw on all of your past experiences with
Science when structuring your responses.

1. What are the three main classes of Biological compounds?

2. In what type of food would you expect to find protein?

3. Explain what trace elements are.

4. Identify which elements below are elements essential for the proper
functioning of the human body.

hydrogen oxygen
carbon selenium
copper magnesium
iron lead

5. Is there a relationship between Biology and Chemistry? Circle one Yes / No
If yes, explain the relationship.

6. What happens when you open a bottle of perfume in a closed room?

51

7. If someone dropped a sugar cube into one end of a swimming pool, would
you be able to test it at the other end? Why or why not?

8. Are there optimum conditions for life? If yes, describe them.

9. All living things contain enzymes. What are they and how do they work to
maintain the proper function of living things?

52

Results of the Pretest

1. What are the three main classes of Biological compounds?

W moses
inorganic/organic 12 or 60 %
animal/plantflungi 1 or 5%
metals/non metals 1 or 5%

no answer 6 or 30 %

2. In what type of food would you expect to find protein?

Muses W
meat 14 or 70 %
beans 2 or 10 %
meat and beans 2 or 10 %
pasta ' 1 or 5%

no answer ' 1 or 5%

3. Explain what trace elements are.

83mm W
inorganic elements 1 or 5%
small amounts of an element 7 or 35%
essential to life 2 or 10%

no answer 10 or 50%

4. Identify which elements below are elements essential for the proper
functioning of the human body..

Element Pereent indieeting it is eeeentiel
hydrogen 17 or 85%

carbon 18 or 90%

copper 4 or 20 %

iron . 18 or 90%
oxygen , 19 or 95%
selenium 1 or 5%
magnesium 10 or 50%

lead 0 or 0%

53

5. Is there a relationship between Biology and Chemistry? Circle one Yes I No
If yes, explain the relationship.

_Reepeflees meurrenees
NO 0 Of 070

Yes 20 or 100%
Reepenge (feeling with the reletienehip mourrences
involves the existence of life 9 or 45%
both are types of science 2 or 10%
Biology is part of Chemistry 6 or 30%
cells do chemistry to survive 1 or 5%

no response 2 or 10%

6. What happens when you open a bottle of perfume in a closed room?

Deaconess Occurrences
utilized term diffusion 8 or 40%
described diffusion 12 or 60%

7. If someone dropped a sugar cube into one end of a swimming pool, would
you be able to test it at the other end? Why or why not?

Responses M
NO 16 01’ 8070
Yes 3 or 15%
Maybe 1 or 5%
Reeeenge ef ingividgels reemnging Ne Meeeee
too much water 1 or 6%
chlorine would eliminate flavor 3 or 19%
sugar concentration too low 12 or 80%
Reepenge ef ineiviggel reeeending Yee W
Diffusion 3 or 100%

The individual responding Maybe indicated that it would depend on
size of the pool.

8. Are there optimum conditions for life? If yes, describe them.

_Fiesopeses Wises
No 4 or 20%
Yes 15 or 75%
No response 1 or 5%

Reepeneee ef ineiviggel ineieeting Yee W

food 7 or 47%
oxygen 3 or 20%
sunlight 4 or 27%
water 7 or 47%

9. All living things contain enzymes. What are they and how do they work to
maintain the proper function of living things?

Reemneee invelving the fellewing termmneepte mourreneee
proteins 7

homeostasis
catalyze reactions
no response
provide energy
RNA or DNA

443mm

55

Appendix D

Model Building - Teacher Notes
Time - 3 class periods

Pert 1: the mnejgmien ef meeel lipid meleeglee

Before beginning, show students the structural formulas of the molecules which
are going to be constructed. Molecules that work well to demonstrate the
differences between saturated and unsaturated fats are Palmitic acid or Stearic
acid, for saturated fats, and Oleic acid for an unsaturated fat.

Show students the position of the functional group. Discuss the relative position
and how this relates to the function of the molecule. Include a discussion of
how functional groups are the site of reaction in organic molecules. Compare
the flexibility of a saturated and an unsaturated lipid. This can be used to draw
a connection to a biology concept, Fluid Mosaic Model.

P- _2 11 #111 in 01min“ 'mo-l ..rh-.- or-t: - 0 -0lTlil"l -, 1

Have student groups construct from models a simple carbohydrate like glucose.
Discuss how this is a monomer of the larger carbohydrate polymer. Have
groups condense their molecules to form a disaccharide. Students should
observe where the functional groups are located on the simple carbohydrates.
Functional groups should be identified. Also, students should observe the
source of the atoms that make up the water molecule that is created during the
condensation reaction.

Have students hydrolyze their disaccharides. Students should note how the

water molecule is broken up into a H+ and a OH'. Also, the attachment of these
ions on glucose should be noted by students.

The same general procedure can be repeated with the construction of amino
acids and proteins.

Resources:
Bie-Leerning Geige, Burgess Publishing Company, 1975
An lntrfiugien ef Melfigler Bielegy, J. Weston Walch, 1986

56

Appendix E
What Is it?

There are three main classes of compounds in Biological systems:
Carbohydrates, Lipids and Proteins. During this series of laboratory activities,
you will learn to test for each substance and determine the identity of an
unknown sample.

Carbohydrates include simple sugars, starches and other complex sugar
compounds. Glucose is one of the most familiar simple carbohydrates. The
most common test for a simple sugar is the Benedict's test. Benedict's

Qualitative solution is an aqueous solution of Cut2 ions that in the presence of
a reducing sugar (a few examples are Glucose, Lactose, Maltose and Fructose)

forms CuzO ( red precipitate) where the Cu+2 ion reduces to Cu“. Reducing

sugars have either a free aldehyde or a free ketone group. If either of these is
not available, then the sugar is not a reducing sugar and cannot be detected
with a Benedict’s test.

Benedlg’e Qgelltetlve Tat:

Meterlale:

test tubes ( 7 ) Hot water bath
Benedict's solution Distilled water
6 samples 10 mL graduated cylinder

P42299319;

1. Put on your goggles

2. Obtain seven test tubes and label them 1 - 7 with a wax pencil.

3. Place 1 mL samples into each sample tube using the table below as a
guide.

4. Add 3 mL of Benedict’s solution to each test tube.

5. Put the tubes into a boiling water bath for five mins. Caution - HOT

6. Cautiously remove the test tubes from the water bath with tongs.

7. Record the colors of each test tube in the space provided on the data table.

57

San'ple Color before Color after

pulverized fruit
_S}6_glucose
S96 maltose
S96 lactose

 

 

 

 

 

5% sucrose
5% fructose

distilled water

Anll tin:

 

 

 

 

 

 

 

1. Which tube is your control or standard for comparison?

2. Draw glucose, lactose, maltose and fructose. Which are disaccharides?
Which are monosaccharides?

3. Which sugars you tested are reducing sugars? How did you reach this
conclusion?

4. Do all reducing monosaccharides develop the same color?

5. Do all reducing disaccharides deveIOp the same color?

6. Can you use this test to infer if something is a monosaccharide or a
disaccharide?

58

Complex Carbohydrates

Complex carbohydrates are large molecules with many repeating units of
monosaccharides. Complex carbohydrates are biological examples of
polymers. The simple sugars, like glucose, are the monomers. These
polysaccharides include molecules like cornstarch and cellulose. The average
monosaccharide has a molecular weight around 130 - 170, while the average
polysaccharide has a molecular weight around 500,000. They are so large they
do not dissolve, but rather form suspensions in water. The functions of
polysaccharides includes being part of cell walls, being a unit of cellular fuel
and energy storage.

Lugols Iodine is a red/brown liquid that will change to a purple/black color in
the presence of some polysaccharides like starch. The iodine molecules from
the Lugols solution form a complex with the starch molecules. This complex is
easily disrupted by heat and pH changes.

leelne Teet:

Meterlels:

4 test tubes distilled water
Lugols iodine 5 % glucose solution
corn starch solution glycogen solution

Precedgre:

1. Put on your goggles.

2. Label the 4 test tubes numbers 1 - 4.

3. Fill the test tubes according to the data table.

4. Add 4 drops of Lugols to each test tube.

5. Agitate each tube gently. Observe and record the color of each test tube.
Record your results in the data table.

 

 

 

 

 

Data Table:
Tube # Substance Color
1 distilled water
2 corn starch
3 mi
4 ggcose

 

 

 

 

 

59

Anelysle Qgeetlone:

1. What is the role of glycogen in humans? What is the chemical monomer of
glycogen?
2. Which substance(s) were starch-like polysaccharides?

3. Which test tube represents your control?

4. What is the function of starch in plants? What is its chemical monomer?

5. What can you conclude about glucose?

60

Proteins

Proteins are another example of a biological polymer. The individual units,
monomers, are called amino acids. All proteins have peptide bonds between
amino acids. All amino acids have two functional groups: a carboxyl group and
an amino group. Proteins have a variety of roles in Biological systems ranging
from things like muscle tissue to enzymes, biological catalysts.

There are two tests for proteins: 1. the foamlfroth test and 2. the biuret test. In
this laboratory experience both tests will be performed.

lite Feem I Freth Tm:

Meterlele:

5 test tubes goggles
graduated cylinder distilled water
5% glucose corn starch
salad oil distilled water
egg white

Pr r :

1. Put on your goggles.

2. Label the test tubes 1 - 5 with a marking pen.

3. Place 3 mL of sample into each tube as indicated on the data table at the
end.

4. Gently agitate the test tube, be careful not to slash the substance on your
skin. '

5. Observe the top portion of the liquid for the appearance of a foam.

6. The presence of foam I froth is a positive test for protein.

7. Record your observations on the data table.

8. Save your test tubes for the next experiment.

The Blgrg Tat:

The biuret test can burn your skin and eyes. Wash immediately from your skin
and notify the instructor. Be sure to wear you goggles during the entire
procedure.

61

The Blgrg Test eent’:

 

 

 

 

 

 

Meterlele:
5 test tubes from the foam/froth test goggles
dropping pipet graduated cylinder
10 % NaOH 0.5 % CuSO4
distilled water
Pr ure:
1. Put on your goggles.
2. Use the test tubes from the foam lfroth test.
3. Add 2 mL of 10 % NaOH to each test tube.
4. Add 8 drops of 0.5 % CuSO4.
5. Using caution, agitate gently.
6. Record the color of the solution after 5 minutes in the data table below. A
pink, purple or violet color is a positive test.
D t T l
_I__dstilled_water
_LM

3 com stamh
_A__salad_oiL

5W

 

 

 

 

 

 

 

 

 

Anal ale u tl n :

1. Which tube was your control in both of your testing procedures?

2. Which sample(s) was a protein?

3. Which test do you prefer? Explain your choice.

4. In both testing procedures, which substances were not proteins?

62

The Fat Test

Lipids are found in all biological systems. The major function of lipids are to:

1. be a building block of the cell membrane, 2. serve as protection in plants,
animals and bacteria, 3. store and transport vitamins and hormones, 4. provide
energy storage. One group of lipids is called fat. The role of fat is to provide
animals with insulation and energy storage. Fats are easily tested for by wiping
a small sample of them on brown paper bags. If the paper becomes
translucent, the sample is a fat.

Materlele:

Cooking oil
margarine

butter

fat free butter spread

distilled water
5% glucose

Proeedure:

1. Obtain 6 pieces of brown paper and label with the sample names.
2. Wipe a small amount of each sample on the matching piece of brown paper.

3. Hold the paper in front of a light and observe. If the paper has become
translucent in the area of the sample, it is a fat.

4. Record your observations on the data table.

63

Data Teele

 

 

 

 

 

 

l' 1
mm

 

 

 

 

 

 

Anl ls u tln:

1. Where the results what you expected? Explain your answer.

2. What was your control?

64

Identification of an Unknown

You are employed as a lab worker at a local research facility. You have been
provided with a 25 mL sample of an unknown substance. Develop a procedure
to identify this unknown using your previous experiences. You must:

1. Create a data table to show the test done and the results.

2. Identify the sample and support the conclusion with evidence.

3. Write a letter to your supervisor explaining what you did and why.
Include a detailed description of any hazardous waste generated.

If you run out of sample, it will cost you 5 points for every 5 mL that I need to give

you extra. Use your sample wisely. If your procedure is cost effective and
environmentally friendly, you will gain 10 extra points.

65

What Is It? - Teacher Notes - Benedlct’s Qualitative Test
Time - 1 period

Prepare the Benedicts solution in advance. Each group will need about 25 mL.

Benedicts solution:

Solution 1 - 173 g of sodium, citrate plus 100 g of sodium carbonate in 70 mL of
distilled water. This solution is very thick,

Solution 2 - 17.3 g of CuSO4 in 100 mL of distilled water.

Add solution 2 to solution 1 and dilute to 1 L with distilled water. You may need
to heat it but stirring thoroughly for 5 to 10 minutes will work.

Prepare a 5% solution of each of the following: glucose, maltose, lactose,
sucrose and fructose. Each group will need 1 or 2 mL of each solution.

Prepare a hot water bath. The water needs to be gently boiling.

Safety Notes:

1. Goggles should be worn.

2. Have students exercise caution when using the hot water bath.

3. None of the solutions should be consumed.

4. Do not put Benedict’s Qualitative solution down the drain. It contains
copper which is a bio-accumulating toxin.

Solutions to Questions:

1. Which tube is your control or standard for comparison?
The control is the tube with distilled water.

2. Draw glucose, lactose, maltose and fructose. Which are disaccharides?
Which are monosaccharides?

3. Which sugars you tested are reducing sugars? How did you reach this
conclusion ?

Glucose , fructose, maltose and lactose are all reducing sugars. Students
should reach this conclusion from the analysis of their laboratory work.

4. Do all reducing monosaccharides develop the same color?
Student responses will vary.

5. Do all reducing disaccharides develop the same color?
Student responses will vary.

66

6. Can you use this test to infer if something is a monosaccharide or a
disaccharide?
Student responses will vary.

What Is It? - Teacher Notes - Complex Carbohydrates
Time - 1 class period

In advance, prepare a 5% corn starch solution and a 5% glycogen solution.
Shake the corn starch solution prior to student use. Students will use 3 mL of
each solution

Lugols iodine is available commercially. Each lab group will need a small (25
mL) dropper bottle of Lugols.

Safety Notes:
1. Goggles should be worn.

Solutions to Questions:

1. What is the role of glycogen in humans? What is the chemical monomer of
glycogen?

Glycogen is the molecule that glucose is converted to when it is not
immediately used by the body. The monomer is glucose.

2. Which substance(s) were starch—like polysaccharides?
Students should identify corn starch and glycogen as starch -like
polysaccharides.

3. Which test tube represents your control?
Students should indicate the tube with distilled water was the control.

4. What is the function of starch in plants? What is its chemical monomer?
Starch is the nutritional reservoir in plants. The monomer is glucose.

5. What can you conclude about glucose?
Student responses will vary.

67

S1234

C\

What Is It? - Teacher Notes - Proteins
Time - 1 class period

Prepare a 10% solution of NaOH, a 0.5% solution of CuSO4 and a 5% solution

of glucose in advance. A good source of protein is egg white. Provide student
with a variety of compounds to test.

Safety Notes:

1. Goggles should be worn.

2. Samples are not meant to be eaten.

3. NaOH is very caustic.

4. Do not allow students to dispose of compounds containing copper down the
drain. Copper is a bio-accumulating toxin.

Solutions to Questions:

1. Which tube was your control in both of your testing procedures?
Student responses should indicate the tube with distilled water.

2. Which sample(s) was a protein?
Student responses should reflect samples with a positive foam/froth test
and/or a positive Biuret test.

3. Which test do you prefer? Explain your choice.
Student responses will vary

4. In both testing procedures, which substances were not proteins?

Student responses should reflect samples with a negative foam/froth test
and/or a negative Biuret test.

68

Tim
Prel
Gat
oil, I

Prio
bag

Hay
3811
1. l
2. I
Soil
Stu
2. ‘-
The

What Is It? - Teacher Notes - Fat Test
Time - 1 class period

Prepare a 5% glucose solution in advance. Students will only need 1 or 2 mL.
Gather a variety of samples (at least on of each of the following should be used:
oil, margarine, butter and butter substitutes) from the grocery store.

Prior to beginning, cutout 2” x 1' samples of unglazed paper. Brown paper
bags work well.

Have the students rank the samples in order of decreasing fat content prior to
beginning. After completing the activity, have students revisit their predictions.

Safety Notes:

1. Goggles should be worn.

2. Samples should not be eaten.
Solutions to Questions:

1. Where the results what you expected? Explain your answer.
Student responses will vary.

2. What was your control?
The sample with distilled water is the control.

69

What
ldent

Time
All of
agair
be re

Sele

9.,

ewwem
nrnrnmm

:17

SS

93
o

ETIE’I;

I? I.

What Is It? - Teacher Notes - Assessment
Identificatlon of an Unknown

Time - at least 2 class periods.

All of the testing reagents provided for the four previous activities will be needed
again. Students will be working independently and more of each reagent will
be required by the class.

Selection of the unknown - select unknowns from the samples used in the prior
activities.

Safety Notes:

1. Goggles should be worn.

2. Safe handling practices for all reagents should be followed.

3. Safe disposal practices for all reagents should be followed.

4. Caution should be exercised around the hot water bath.

Resources:

Bie-Leerning Geige, Burgess Publishing Company, 1975

Experimentel Metheee in Meeem Bigghemiggy, W. B. Saunders Co., 1971
Intrmgetien te Bieehemigry, W. B. Saunders Co., 1978

Intreegetien te Pretein Qhemigry, John Wiley & Sons, Inc., 1957

70

Eceedakd

Cycnliuvc priicp

Tvpa

PL

['3

Appendix F
Diffusion

Diffusion is defined as the net movement of molecules from a region of high
concentration to one of low concentration, due to their kinetic energy. Diffusion
explains why when perfume is sprayed in one corner of a room, before long,
every one in the room can smell the perfume. The particles of perfume have
diffused throughout the room. At this point, diffusion does not stop, it continues
and the concentration of perfume particles gets lower and lower until we can no
longer smell the perfume. Cells in living systems depend on the process of
diffusion.

Several factors impact the rate of diffusion: molecular weight, temperature and
concentration. In the first of the two diffusion experiments, you will observe the
rate of diffusion of several ions through an agar medium. Salt solutions
(sodium chloride, potassium iodide and potassium ferricyanide) with identical
concentrations will be placed into wells within the agar. You will observe a

precipitation reaction between the cation, Ag+, and the three anions. This
reaction models the Ouchterlony method of antibody/antigen reactions. The
Ouchterlony method is an antibody/antigen reaction on agar where a
precipitation occurs when there is an antibody/antigen match.

The second experiment you will perform will explore the effect of molecular
weight on diffusion rates. Agar is a colloid. Colloids are suspensions of large
particles that do not settle out. Diffusion occurs through the spaces between the
agar particles.

Diffusion Experiment #1

Form a hypothesis about the relationship between molecular weight and the
rate of diffusion.

Determine the molecular weights of the ions involved and predict which will
diffuse the fastest and which will diffuse the slowest.

71

 

Mat
age

0.1
0.1I

PTOI

Materials:

agar plate cork borer #5 or #6
0.1 M NaCl 0.1 M AgN03
0.1M Kl 0.1 M K3Fe(CN)5
Procedure:

1. Put on your goggles.

2. Use a number 4 or 5 cork borer to punch three wells into the agar within your
petri dish. Use the template below to help you.

3. Remove the agar plugs carefully. Using a toothpick or twisting the cork borer
can be helpful.

4. Label each well ( A - KaFe(CN)6, B - KI,C - NaCI and D - AgNOa).

5. Fill each well with the appropriate solution. Fill well D last with silver nitrate.
Use caution with silver nitrate, it can stain your skin. Cover the plate and make
observations once every minute.

6. You will be able to see the silver ions migrate through the agar. When the
two ions encounter one another, the silver will appear to stop. Record the
amount of time needed for this to occur.

00

72

 

 

 

Dc

Di:

6. Complete the data table with the information gathered. Rank the total time it
took or the precipitate formation, 1 being the fastest and 3 being the slowest.

Well ion time rank

 

 

 

C

 

 

 

 

 

 

Answer the following questions to the best of your ability.

According to your data, which ion moved the fastest? Does this ion have the
smallest molecular weight?
How do your rates compare with your known molecular weights?

Do your results agree with your predictions?

Diagram your plate below.

73

Diffusion Experiment #2
Diffusion Rates and Molecular Weight Determination
In this experiment, you will estimate the molecular weight of three unknown

dyes based on their rate of diffusion compared to the diffusion rates of three
knowns.

Materials:

Agar plate Cork borer #1 or #2
dropping pipet unknown #1
unknown #2 unknown #3

.1 M KMnO4 crystal violet
satranin - 0

Procedure:

1. Put on your goggles.

2. Punch 6 equidistant holes in the agar plate. See the diagram below for help.
3. Remove the agar plugs carefully, avoid tearing the agar.

4. Number the bottom of the plate below each well as indicated on the diagram
below.

5. Fill the wells according to the information below. Be careful not to overfill the
wells.

6. Place the plate into an incubator at 50.0 C for 30 min.

7. Take out plates and measure the diameter of each dye ring in millimeters.

8. Plot the molecular weight ( y axis) vs. the distance diffused ( x axis ) of the
three known dyes.

9. Draw a best fit line for your three known points. Use this line to interpolate
the molecular weight of the three unknowns.

10. Determine an equation of your best fit line.

74

OOOOOO

Diagram of plate

Analysis Questions:

1. Obtain the actual molecular weight of the three unknowns from the instructor.
Determine your percent error using the following formula. Show your work.

percent error = observed - expected [expected x 100 %

2. Diagram your results in color.

3. What other factors maybe influencing the rate of diffusion.

75

F

E

CC12

C»

F

r

CunECII Ira/Tr

a: If <\ l\

Diffusion - Teacher Notes - Experiment #1
Time - 1 class period

Prepare the agar plate in advance. This does not need to be sterile agar.
Recipe for agar: 15 g of agar per 1 L of distilled water. Heat and stir until all
solid is dissolved and the solution begins to boil. Once the solution is
transparent, you can pour the plates.

Prepare the salt solutions in advance. All of these solutions should be 0.1 M.
Each group will need no more than 1 or 2 mL of each solution.

Safety Notes:
1. Goggles should be worn.
2. The solutions are not meant to be eaten

Solutions to Questions:

Form a hypothesis about the relationship between molecular weight and the
rate of diffusion.

Students should hypothesize that the rate of diffusion decreases with increasing
molecular weights.

Determine the molecular weights of the ions involved and predict which will
diffuse the fastest and which will diffuse the slowest.

AgN03 = 170

KI = 165

NaCI = 58

K3Fe(CN)5 = 317

slowest - K3Fe(CN)6. K I, NaCI - fastest

According to your data, which ion moved the fastest? Does this ion have the
smallest molecular weight? Students should identify NaCI as the fastest and
smallest ion.

How do your rates compare with your known molecular weights?
Students should find that the larger a molecule is the slower it diffuses.

Do your results agree with your predictions?
Student responses will vary.

Diagram your plate below.
Student responses will vary.

76

Diffusion Rates and Molecular Weight Determination
Time - 1 class period

Suggestion: this lab does work in 50 mins it a drying oven set at 50 C is used.
But, better results are obtained in 90 minutes. It may work to have a group set
up an experiment and then have 1 member from each group return in 90
minutes to complete the measurements. This part only takes 5 minutes. Also, if
you do not have all of the suggested dyes available, you can change with those
that are available. It is recommended that you then do the experiment ahead of
time to check the results.

Prepare the nonsterile agar plates ahead of time.

Each group will use no more than 1 or 2 ml of each sample being used.

Knewne
aniline blue - a 1% solution should be sufficient.

KMnO4 - 0.1 M solution

Bromocresol purple - a 0.1% to a 1% solution should be sufficient.

unknewne
Unknown #1 - 0.1 M K3Fe(CN)6

Unknown #2 - Rhodamine - a 1% solution.
Unknown #3 - Brilliant Cresyl Blue - a 1% solution.

When I did this experiment, drawing a best fit line with three points by hand, I
had between 10 % and 18% error. The best fit line would probably be more
accurate it done as a computer activity. An extension of this laboratory
experience would be to create a computer activity to deal with the data analysis.

Resources:
Bie-Leerning Geiee, Burgess Publishing Company, 1975

Bielegieel fiieneee 11g -111 Lemretog Mengel, Hayden - McNeil Publishing
Inc. 1995

Nee e51, e52 Lemretegy Menuel end Qeuree Guide, Summer 1994 pages 107
- 111

The Affeg ef the Melfigler Weight on the R t fDiff ' n in cht rl n
Diffgeien Methfl, submitted to the NSF Molecular Biology Workshop, 1987

 

77

Appendix G
Exploring Enzymes

Enzymes are biological catalysts that catalyze 1000’s of chemical
reactions every minute. Each reaction in a biological system is catalyzed by
one enzyme. The material acted on by an enzyme is called the substrate. In a
typical reaction, the sabstrate binds with an enzymes active site, which is the
region of an enzyme which catalyzes the reaction, and is converted into the
reaction products. Enzymes are proteins which have a unique amino acid
sequence. It is the three dimensional shape of the enzyme which creates the
active site. Many factors can affect the 3 dimensional shape of an enzyme and
alter its function.

In this set of experiments, you will be exploring the factors that affect
enzyme function. The factors include temperature, pH, substrate concentration,
enzyme concentration and salinity. In our bodies, we Operate at an optimal pH,
temperature and salinity. We will explore it this is also true for the enzyme
catalase.

Catalase is the enzyme used by living organisms to destroy peroxide
(H202), a common product of metabolism. The following is the balanced

chemical reaction for the breakdown of peroxide:

2 H202+catalase ------------- > 2 H20 + 02 + catalase

Catalase is found in all living systems. For this investigation, it will be obtained
from potato’s.

Materials:

4 large bottom test tubes (100 mm x 20 mm )
test tube rack

berol pipette

filter disks

3% peroxide

catalase

distilled water

78

Prtf- t nntrtln

1. Obtain 5 reagent cups and label them one through five.
2. Fill the 5 reagent cups as indicated on the table below.

mL catalase + mL cistilled water - 96 catalase
5 mL 0 mL 100 96

4 rd. 1 mL 80 96

3 mL 2 mL 60 96

2 mL 3 mL 40 96

1 rd. 4 mL 20 96

0 ml 5 mL 0 96

3. Store the reagent cups on ice water.

4. Put 5 ml of peroxide in each test tube ( label A through E).

5. Soak the filter disk in the first enzyme solution and place into test tube A.

6. Record the time for the disks to rise from the point it touches the bottom till it
rises to the surface.

7. Repeat three times with tube A using fresh peroxide.

8. Repeat steps 4 - 7 for the other concentrations of catalase.

9. Record all the data on the data table.

10. Graph enzyme activity (fltime) vs. % catalase.

Prt2-u rt nntrtln

1. Fill the test tubes labeled A - E according to the chart below.

96 peroxide mL of peroxide mL of water
0 0 4
0.75 1 3
1.5 2 2
3 4 0

2. Using the full strength catalase, soak a filter disk and and determine the rate
of reaction. Repeat the procedure 3 more times for each concentration.

3. Complete the data table and graph the catalase activity vs. substrate
concentration.

Pert e - Temeeratgre

1. Label three test tubes ( 1, 2, and 3 respectively).
2. Place 5 mL of peroxide in each test tube.

79

Place test tube 1 into an ice bath. Wait 5 min. Obtain a thermometer to
observe and record the temperature.

Place test tube 2 in a rack. Wait 5 min. Observe and record the temperature.
Place test tube 3 in a beaker of heated water. Observe and record the
temperature.

NOTE- take the temperature of the peroxidel

4.
5.
6.
7.
8
9

1
2.
3

Soak a paper disk in the enzyme solution. Add to test tube one and
measure enzyme activity. Repeat the process 3 more times using fresh
peroxide.

Repeat step 6 for tubes 2 and 3.

Place your results on the data table.

Graph enzyme activity vs. temperature.

Obtain 5 reagent cups. Label them 1 through 3.

#1 is the control; #2 is the acid environment and #3 is the basic
environment.

In each reagent tube place 1 mL of enzyme and 3 mL of the correct buffer
solution.

Distilled water is the buffer for the control cup.

Obtain 3 test tubes. Add 5 mL of peroxide to each.

Soak a filter disk in enzyme mix #1 and add to the first test tube. Repeat this
process three additional times.

Repeat steps 5 and 6 for reagent cups #2 and #3.

Place your results on the data table.

Graph enzyme activity vs. pH.

80

How Specific Are Enzymes?

As you recall, enzymes are proteins which act as catalysts for biochemical
reactions. One of the characteristics of enzymes is their tendency to react with
only one substrate or class of substrates. This phenomenon is called enzyme
specificity. The active site of an enzyme is the region of the molecule that binds
to the substrate. The lock and key hypothesis states that there is only one
substrate that is able to bind with a specific active site.

In these lab exercises, you will explore the substrate specificity of two different
enzymes, sucrase and amylase. The first experiment examines the affinity of
sucrase for sucrose compared to its affinity for cornstarch. Both potential
substrates are carbohydrates. Sucrose is a disaccharide and corn starch is a
complex carbohydrate.

The Substrate Preferences of Sucrase

Meterlele:

3 - 250 mL beakers 3 - 3 or 4 inch pieces of dialysis tubing
thread sucrase enzyme solution

cornstarch solution 10 % maltose

10 % sucrose Hot water bath

distilled water Benedicts solution

4 test tubes

Proeedure:

1. Obtain 3 beakers, label them 1 - 3 and half fill them with distilled water.
2. Securely tie off one end of each piece of dialysis tubing. It helps to twist the
end first.
3. Fill each bag according to the chart below:
1 - 5 mL of sucrase and 5 mL of sucrose
2 - 5 mL of sucrase and 5 mL of cornstarch
3 - 10 mL of cornstarch or maltose
4. Tie off the top of each bag and place it in its respective beaker.
5. Wait 20 minutes. During this time, test each substance for glucose with
Benedicts solution.
a. obtain and label four test tubes 1 -4
b. Place a 1 mL sample from the chart below into the tubes.
#1 - distilled water
#2 - cornstarch
#3 - sucrose ( a non-reducing disaccharide)
#4 - maltose ( a reducing disaccharide)

81

c. add 3 mL of Benedicts solution to each tube.
d. Heat for 5 minutes in a hot water bath.
e. Observe and record the color in the data table.
f. Dump the contents of the test tubes in a copper/Heavy metal
container.
9. Wash tubes.
6. After 20 minutes, take 1 mL samples from each beaker and place in the
corresponding labeled test tube ( 1 - 3).
7. Follow the Benedicts test as outlined in steps a - f.

DtTl:

Substance Benedicts Conclusion
distilled water

 

 

 

‘Q’Qg’ cornstarch
QQ’ sucrose

maltose

 

 

 

Beaker 1
Beaker Z
Beaker 3

 

 

 

 

 

 

 

 

Anal l u tln:

1. Why did you test the first 4 samples with Benedicts?

2. What is the substrate for sucrase?

3. How specific is the reaction of sucrase to its substrate? How did you reach
the conclusion?

4. Explain the reaction between sucrase and its substrate?

5. Dialysis tubing is a selectively permeable membrane similar to a cell
membrane. What have you learned about the size of particles that can diffuse
through the membrane?

82

The Specificity of Amylase

In this experiment, you will extract your amylase from germinating barley seeds.
Then, you will explore the substrate preferences of amylase.

Meteriele:

15 - 20 Barley seeds 5 test tubes

paper towel plastic wrap

cheese cloth distilled water

mortar and pestle water bath

Benedicts solution cornstarch solution
sucrase centrifuge

100 mL beaker graduated cylinder (50 mL)
Preeedgre:

Preparation of amylase

Day 1:
Soak the barley seeds overnight in 50 mL of distilled water.

' Day 2:
Pour barley seeds and water into paper towel. Soak the towels. Cover with
plastic wrap to prevent the seeds from drying out.

Day 3:
Wet down the paper towel.

Day 4:

1. Crush and grind the barley seeds in 20 mL of distilled water with a mortar
and pestle.

2. Pour extract through cheese cloth and collect the extract in a test tube.
Squeeze the cloth to get all of the liquid.

3. Centrifuge the barley extract for 2 - 4 mins. Use the supernatant as your
source of amylase.

The specificity of amylase

1. Obtain 4 test tubes and label them 1 - 4.

2. Put 3 mL of cornstarch in test tubes 1 - 3 and 3 mL of distilled water in tube
#4.

3. Add the reactants as indicated on the data table.

4. After 5 minutes, add 3 mL of Benedicts solution to each test tube. Place in a
hot water bath for 5 minutes.

5. After 5 minutes, record the color in the data table.

6. Complete the data table.

83

Date Tagle:

IuDquncmant qupr Conclus'pn
1 AW

 

 

 

 

 

 

 

 

 

 

Anll tIn:

1. Why is Benedicts a useful test for these reactions.

2. Considering your source of amylase, why is it possible to get a slight amount
of precipitate formation with the Benedicts solution?

3. What would happen if amylase was added to a sucrose solution? If you
have enough left, try it and see.

4. Explain why you think enzymes are limited to one substrate of class of
substrates.

5. Why are germinating barley seeds such a good source of amylase? What
role does amylase play in the germinating seed?

84

Exploring Enzymes
Teacher Notes

Time - 3 or 4 class periods

In advance, prepare the catalase solution. Catalase can be made by mixing
ice, distilled water and potato in a blender. Use cheese cloth to strain the
catalase assay.

Filter disks can be prepared by using a hole punch on a piece of filter paper.

Test tubes need to have a large bottom. Typically, test tube which have an
opening of 20 mm are large enough.

Peroxide is the substrate of catalase. The 3% hydrogen peroxide typically sold
is fine.

The rate of enzyme activity is defined as the inverse of the time required to float
the disk.

This activity lends itself to testing a variety of factors on enzyme activity.
Possible extension topics: testing the effect of pH, testing the effect of salinity
and testing the effect of temperature.

How Specific Are Enzymes
Teacher notes

Time - 1 class period

Have 1/2 of the class use maltose in bag 3 and 1/2 of the class use cornstarch.
maltose is a reducing disaccharide that will help demonstrate the selectivity of
the selectively permeable membrane. Maltose will not go through but glucose
will. This is an interesting area for discussion.

Sucrase is a yeast water mixture. Add 5 g of yeast to every liter of distilled
water.

Benedicts qualitative solution can be bought ready made or mixed.
Solution 1 - 173 g of sodium citrate plus 100 g of sodium carbonate in 70 mL of

distilled water. This solution is very thick.
Solution 2 - 17.3 g of CuSO4 in 100 mL of distilled water.

Add solution 2 to solution 1 and dilute to 1 Liter with distilled water. You may

85

need to heat it but stirring thoroughly for 5 to 10 minutes will work.
The cornstarch solution can be a solution between 3% and 5%.
The hot water bath needs to be between 90 C and 100 C.
Analysis questions:

1. Why did you test the first 4 samples with Benedicts?

Students should use this as a basis for comparison.

2. What is the substrate for sucrase?

The substrate for sucrase is sucrose.

3. How specific is the reaction of sucrase to its substrate? How did you reach
the conclusion?

Students should note that the reaction is very specific. Sucrase did not react
with anything else.

4. Explain the reaction between sucrase and its substrate?

Sucrase is the catalyst for the breakdown of sucrose into glucose and fructose.
5. Dialysis tubing is a selectively permeable membrane similar to a cell
membrane. What have you learned about the size of particles that can diffuse
through the membrane? Only monosaccharides like glucose seem to be able
to pass through. If maltose was used, it should be noted that it could not be
detected.

Resources:

Bimhemigg, W. H. Freeman and Company, 1981

Exercige in Bielegicel Seieneee, Vlfillard Grant Press, 1985
pH 8: Rete ef Enzmetie Reegiene, American Biology Teacher, v. 53, n. 6

86

Appendix H
Biochemistry Unit Test

Directions: Answer each of the following to the best of your ability. Place your
answers in the space provided on the answer sheet.

1. Lipids are commonly found in
a. cell membrane b. stomach c. pancreas d. none of the
above

2. Lipids are commonly used in our bodies as a source of

a. water b. electrical stimuli c. energy d. obesity
3. A saturated fat has

a. no double or triple bonds b. only single bonds
c. some double and single bonds d. a and b

4. Which of the following is not a lipid?

a. butter b. oil c. egg white d. lecithin

5. There are _ major categories of lipids.

a.1b.2 c.3 d4

6. Which of the following is not a lipid?

a. cholesterol b. lecithin c. terpenes d. amylase

7. We test for fats using

a. Benedicts solution b. brown paper

c. the froth test d. none of the above

8. We test for simple carbohydrates using

a. Benedicts solution b. brown paper

c. the froth test d. none of the above

9. We test for proteins using

a. Benedicts solution b. brown paper

c. the froth test d. none of the above

10. Reducing sugars react with a solution of copper causing the copper to be
a. oxidized b. reduced c. none of the above

11. Carbohydrates contain all of the following elements except for
a. nitrogen b. carbon c. hydrogen d. oxygen

87

12. Many monosaccharides joined together is called a
a. starch b. carbohydrate c. neither a nor b (I. both a and b

13. Excess carbohydrates are stored in the human body as
a. starch b. glycogen c. fat d. oil

14. Two monosaccharides joining together will produce a disaccharide and a
molecule of:
a. water b. sugar c. protein d. fat

15. All enzymes are made of
a. fat b. carbohydrates c. protein d. lipids

16. Which of the following is a functional group found in a protein?
a. amino acid b. sugar c. amino d. organic acid

17. The basic building block of all proteins are called
a. amino acid b. sugar c. amino d. organic acid

18. Enzymes are made exclusively of
a. proteins b. sugars c. lipids d. carbohydrates

19. All proteins have _ levels of organization.
a.1b.2 c.3 d.4

20. Enzymes do all of the following except
a. speed up biochemical reactions b. react with a single substrate
0. use an active site to act on a substrate d. function at high temperatures

21. Lead is often a source of trace element poisoning because it is
a. sweet b. brightly colored c. both a and b d. neither a nor b

22. The most common source of trace element poisoning is
a. ingestion b. injection c. inhalation (1. none of the above

23. is a method of transport in body cells.
a. diffusion b. enzymes c. dehydration d. none of the above

24. What is the substrate for sucrase?
a. maltose b. fructose c. sucrose d. pectin

25. What is the substrate for amylase
a. maltose b. starch 0. sucrose d. fructose

88

26. Decreasing the concentration of a substrate will
a. increase enzyme activity b. decrease enzyme activity c. do nothing

27. Increasing the concentration of an enzyme will

 

a. increase enzyme activity b. decrease enzyme activity c. do nothing
28. We can infer the relative of a molecule by comparing the rates of
diffusion.

a. shape b. size c. molecular weight d. polarity

29. Enzyme activity is tested by extracting catalase from
a. potatoes b. carrots c. peroxide d. meat

 

30. The substrate of catalase is
a. potatoes b. carrots c. peroxide d. meat

 

31. Increasing the saturation of a lipid the flexibility of the molecule.
a. increases b. decreases c. has no effect on

32. Lipids are

a. non-polar b. polar c. neither a nor b

33. Which of the following is not a complex carbohydrate?
a. cornstarch b. glycogen c. amylopectin d. maltose

34. Which of the following is not an enzyme?
a. sucrase b. fructose c. catalase d. amylase

35. There are _ functional group(s) in an amino acid.
a.1b.2 c.3 d.4

89

References

90

References

Allen, J. B., Barker, L. N. and Ramsden, J. H. “Guided Inquiry Laboratory.”
Jegmel ef Qhemieel Egueetien 63 (1986): 533-534

American Association for the Advancement of Science. Seienee fer All
Amerieene. New York: Oxford University Press. 1990

Annapolis High School Core Committee. Ann Ii Hi h
flofle. Dearborn Heights, Mi: 1998

Beall, Herbert and Prescott, Sarah. “Concepts and Calculations in Chemistry

Teaching and Learning.“ Jegrnel ef Qhemieel Egueetien 71 (1994):

111-112
Brady, James and Holum, John. Qhemiamz The fing 91 Met_ter egg lte
gheegee. New York: John Wiley & Sons, Inc. 1993. 362

Ceccarelli, Mary. Personal interview. 6 June 1998

Chiappetta, Eugene L. “Inquiry-Based Science“ The Seienee Teeeher
v. 64, n. 7 (1997) 22-26

Foster, Joseph F. and Fox, Sidney W. Intrmuetien te Pretein Chemigm.
New York: John Wiley & Sons, Inc. 1957. 379 - 384

Leonard, William H. “Ten Years of Research On Investigative Laboratory
Instruction Strategies“ rn l f II i n T hin 18 (1989)
304 - 306

Lewis, Ricki. ReeQinge in Bielegytg Ammeeny we. Dubuque, Iowa: Wm. C.
Brown Publishers. 1992. 19 - 26

Meleca, C. Benjamin, et al. Bie-Leeming Ggide. Minneapolis, Minnesota:
Burgess Publishing Company. 1975. 3.1 - 3.17

91

Nadler, Ken. Personal Interview. Summer 1996

Newton, David E. An Intrmuetien te Melgglar Biology. Portland, Maine:
J. Weston Walch, Publisher. 1986.

Osborne, Jonathan F. “Beyond Constructivism” Scienee Egucetion 80 (1996)
53 - 82

Redina, George. E rim nt M th in M dern Bi h mist . Philadelphia:
W. B. Saunders Co. 1971

Routh, Joseph I. Intrfiugien te Bieehemisry. Philadelphia: W. B. Saunders

Co. 1978

Sterling, Donna and Davidson, Anne. “Relative Chemistry” The Science
my 64, n. 7 (1997) 33-35

Stryer, Lubert. Bixhemigg. New York: W. H. Freeman and Company. 1981.
103 - 110

Tzimopoulos, Nicholas D, et al. Mmem Qhemietgy New York: Holt, Rinehart
and Winston. 1990. 360 - 365

Woolfolk, Anita. Egucetienal Peyehelegy Englewood Cliffs, New Jersey:
Prentice Hall, Inc. 1987. 150 -157

The World ef Chemigg - Qerben e The Age et Pelymere 1985. Videocassette.
UNMARY. 1988

The Werlg ef Qhemiggy - Preteine: Stmgure eng Fengien 1986.
Videocassette. UNMARY. 1988

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