BIOL 1406 – General Biology I
Judy Lehmberg
Introduction
As we have come to appreciate this semester critical thinking is a highly valued student learning outcome today.
Employers expect people who can think critically; teachers want students who can think critically; society needs
citizens who can think critically. Critical thinking is integral to business and economic success in our global
economy, necessary for responsible democratic citizenship, and a vital part of professional practice in a wide
variety of occupations. Having mastered content knowledge is no longer satisfactory; we expect are students to
be reflective, to think creatively, to solve problems, and to communicate clearly. As a teacher my goal is to
encourage students to develop the ability to incorporate facts and concepts in their problem solving and
evaluative thinking.
Because I teach biology I have always tried to get students to look at the world from the view point of a
biologist; to question what they know and how they know it; and to separate knowledge from belief. I want
them to leave after successfully completing my classes with the ability to analyze any new science information
they encounter. To this end I teach the scientific method and emphasize to my students that all science is based
on that method. If a “fact” is in a biology book it is because it has been rigorously reviewed by a number of
biologists.
Course Syllabus
BIOL. 1406 - General Biology I
Spring Semester, 2007
Instructor: Judy Lehmberg
Office: SB 218 Phone: 281-425-6354 e-mail: [email protected]
Division Chair: Carolyn Foster
Office: SB 214
Phone: 281-425-6275
Required Text: Biology - The Unity and Diversity of Life, 11th edition, by Cecie Starr and Ralph Taggart.
Week
Text Chapters and Lecture Topics
Lab
Jan. 15-18
Introduction – You are a guinea pig.
Ch. 1 Invitation to Biology (briefly)
Ch. 27 Biodiversity in Perspective
Ch. 45 Population Ecology, Human Population p. 812-818
Testing
Population Growth
Jan. 22-25
Ch. 47 Ecosystems p. 842-851, p. 858-859
Ch. 48 The Biosphere p. 874-896
Owl Pellets
begin Introductory Chemistry
Jan.29-Feb.1 Ch. 2 Life’s Chemical Basis
finish Introductory Chemistry
Properties of Water
Feb. 5 - 8
Lecture Test # 1 (Ch. 1, 27, 45, 47, 48, and 2)
Ch. 3 Molecules of Life
Molecular Modeling
Feb. 12 - 15
Ch. 3 Molecules of Life continued
Ch. 20 The Origin and Evolution of Life
Biologically Imp. Molecules
Microscopes
Feb. 19 - 22
Ch. 4 Cell Structure and Function
Cells
13
Ch. 5 A Closer Look at Cell Membranes
Diffusion and Osmosis
Feb.26-Mar.1 Ch. 6 Ground Rules of Metabolism
Lecture Test # 2 (Ch. 2, 3, 20, 4, 5, and 6)
Enzymes
Photosynthesis
Mar.5 - 8
Ch. 7 Where It Starts - Photosynthesis
Ch. 8 How Cells Release Chemical Energy
Fermentation
Lab Test # 1
Mar. 12 - 15
Spring Break
Mar. 19 - 22 Ch. 9 How Cells Reproduce
Ch. 10 Meiosis and Sexual Reproduction
Mitosis
Meiosis
Mar. 26 - 29
Ch. 11 Observing Patterns of Inherited Traits
Ch. 12 Chromosomes and Human Inheritance
Reebops
Genetics
April 2 - 5
Ch. 13 DNA Structure and Function
Ch. 14 From DNA to Proteins
DNA
Protein Synthesis
April 9 - 12
Ch. 14 From DNA to Proteins continued
Lecture Test # 3
The last day to drop with a “W” is Thursday, April 12, 2007.
Genes in a Bottle
Karyotypes
April 16 - 19 Ch. 15 Controls Over Genes
Ch. 16 Studying and Manipulating Genomes
prep for DNA Fingerprinting
DNA Fingerprinting
April 23 - 26 Ch. 16 Studying and Manipulating Genomes continued
Ch. 17 Evidence of Evolution
DNA Whodunit
Natural Selection
Apr30-May 3 Ch. 18 Microevolutionary Processes
Ch. 19 Evolutionary Patterns, Rates, and Trends
Lab Test # 2
May 7-10
Lecture Test # 4 or Final Exam - Tuesday, May 8 at 10:30 am
Requirements:
1. QEP Assessments – Several years ago Lee College began a Quality Enhancement Plan (QEP). The QEP is
designed to improve student critical thinking skills through reading. We are currently implementing the QEP in
your biology class. As a part of this project you must participate in pre- and post-testing of your reading and
critical thinking skills. The California Critical Thinking Skills Test (CCTST) and the Nelson Denny Reading
Test are the assessments that will be used. You will take these tests during the first week of class. The post
tests must also be taken near the end of the semester. I will have more specifics on the post tests later this
semester. These tests are required for this course and failure to take them during the specified times will result
in your being withdrawn from the course. However, please be assured that your grade will in no way be
affected by your scores on these tests. Also please keep in mind that the purpose of the QEP is to help you be a
better student.
2. Grading Procedures: Your grade will be determined by 3 lecture tests, 2 lab tests, question sets, daily
quizzes, a miscellaneous activities category that includes field trips, and a comprehensive final exam. If you
14
have an A average before the final exam you will be exempt from the comprehensive final, but will still be
required to take a fourth lecture test.
3. Critical Thinking and Active Learning Exercises. Learning occurs best when you are actively engaged
with the subject matter. Consequently, several critical thinking and hands-on exercises are built in to the
course. Some will be conducted in class and some will be take-home assignments. Points will be earned for
both. Points earned for the in class activities CANNOT BE MADE UP if you are absent or late to class. The
take-home assignments must be turned in by their due dates. Late assignments will not be accepted. I will
give you a set of questions for every topic we cover this semester.
These critical thinking exercises will take two forms: Question and daily Quizzes - I will give you a set of
questions for every topic we cover this semester. Please note you must complete the assignment for each topic
before we discuss that topic in class. If you do not complete the exercises before they are covered in class you
will not get credit for them. I will also give you a quiz over the question sets during the first 5 minutes of every
class period. You must be present at the beginning of each class period to take the quiz.
4. Attendance, Tardiness, and Withdrawal - Class attendance is an important part of your learning experience
and is therefore expected. Research shows that one of the best predictors of grades is regular class attendance.
In addition to missing out on lectures and labs, your grade may also be affected by excessive absences and
tardies. If you miss class, it is your responsibility to inquire about any assignments that were given on that day.
Attendance is required and you may be dropped if you have more than 3 absences. If I drop you for
nonattendance you will have a F in this course. If you have perfect attendance you will be exempt from the
comprehensive final exam.
If you decide to drop the course, it is your responsibility to complete a drop form and turn it in at the Lee
College records office prior to the drop deadline of Thursday, April 12, 2007. If you simply quit coming to
class and do not complete the drop form, a grade of “F” will be received. At the instructor’s discretion, you
may be dropped for nonattendance after three unexcused absences. If you arrive late to class, it is your
responsibility to let me know at the end of class that you are present. Otherwise, you will be counted as being
absent.
5. Academic Integrity - Honest, mature, and ethical behaviors are expected in this class. Cheating on exams,
plagiarism, and other forms of academic dishonesty will not be tolerated.
It is important for you to realize that you cannot memorize your way through this course. You have to be able
to not only understand the concepts, you must also be able to apply them and to see the relationships between
them. In other words, you will not do well on tests if you just memorize the definitions of a bunch of terms, you
must also be able to see how they fit in to "the big picture" of biology, how they relate to each other.
There are a number of things you can do to assure your success in Bio. 1406. One of the most important is
actively participating in a lab/study group. You will form small support "study groups" to work in lab and study
together.
Use the following to determine your grade if you take the comprehensive final. You must take the
comprehensive final if you have an 89 average or below on May 2, 2007.
Lecture Test # 1 = 14%
89.5 - 100% = A
Lecture Test # 2 = 14%
79.5 - 89.49% = B
Lecture Test # 3 = 14%
68.5 - 79.49% = C
Lab Test # 1
= 12%
55.5 - 68.49% = D
Lab Test # 2
= 12%
0 - 55.49% = F
Question Sets = 10%
15
Daily Quizzes
= 10%
Final Exam = 14%
Total
100%
Use the following to determine your grade if you have an A average before the final exam:
Lecture Test # 1 = 17%
89.5 - 100% = A
Lecture Test # 2 = 17%
79.5 - 89.49% = B
Lecture Test # 3 = 17%
68.5 - 79.49% = C
Lab Test # 1
= 14%
55.5 - 68.49% = D
Lab Test # 2
= 15%
0 - 55.49% = F
Question Sets
= 10%
Daily Quizzes
= 10%
Total
= 100%
Make Up Exams - You may take a make up exam ONLY if you have an excused absence or an extreme
emergency. Please try to make arrangements with me ahead of time. Make up lecture tests will consist of 5 to
10 discussion type questions and a set of definitions. They will generally be more difficult than regular exams.
Make up lab tests will only be given during the week of Apr30-May 3.
Miscellaneous Activities are not a required part of the course but you will be rewarded in a variety of ways if
you take advantage of them. The purpose of these activities is to get you out in the field to participate in
biology oriented field trips. You may choose among the following options (as well as several that will be
announced later as I become aware of them). Your options include: 1. The Houston Zoo (get a handout from
me before you go) 2. Marsh restoration/grass planting with the Galveston Bay Foundation 3. Friday trips to
Anahuac National Wildlife Refuge 4. Baytown Nature Center and 5. Volunteer work with the Lower Trinity
River National Wildlife Refuge.
If you have any type of disability I can help you with, please let me know.
PARTICIPATION: students are expected
to be actively involved in performing all labs
to attend all lectures and participate in question/answer sessions during lecture
to perform all assignments
to ask questions during lecture and lab if unsure of the material
to actively take notes during lecture
at the end of the semester if your overall average is within a percentage point or two of the next higher grade,
your participation and miscellaneous activities will be considered to determine your final grade.
16
Practice 1 – Critical Thinking Power Point Presentation
17
18
19
20
21
22
23
24
Practice 2 - Bloom's Critical Thinking and Questioning Strategies - A Guide to Higher
Level Thinking
Blooms Six Levels:
Knowledge - Level 1 - Recall. Remembering previously learned material, recalling facts, terms, basic concepts
ffrom state text. Terms = name list recognize choose lable relate tell recall match define
25
Comprehension - Level 2 - Understand. Demonstrate understanding of the stated meaning of facts and ideas.
Terms = compare, describe, outline, organize, classify, explain, rephrase, show, relate, identify.
Inference - Level 2 1/2 - Demonstrating understanding of the unstated meaning of facts and ideas. Terms =
speculate, interpret, infer, generalize, conclude.
Application - Level 3 - Put to Use - Solving problems by applying acquired knowledge, facts, and techniques in
a different situation. Terms = apply, construct, model, use, practice, dramatize, restructure, simulate, translate,
experiment.
Analysis - Level 4 - Break down. Examining and breaking down information into parts. Terms = analyze,
diagram, classify, contrast, sequence, simplify, summarize, relate to, categorize, differentiate.
Synthesis - Level 5 - Put together. Compiling information in a different way by combining elements in a new
pattern. Terms = compose, design, develop, propose, adapt, elaborate, formulate, originate, solve, invent.
Evaluation - Level 6 - Judge. Presenting and defending opinions by making judgments about information based
on criteria. Terms = judge, rank, rate, evaluate, recommend, defend, justify, prioritize, support, prove.
Practice 3 - Developing Critical Thinking Skills = Doing Well on Biology Tests
The following scoring will be used on your homework and essay questions.
100% - You have submitted a full and complete description. The reader has no more “how” or “why”
questions and all appropriate vocabulary has been included.
80% -Your description is fairly complete; however the reader may still be able to ask you “how” or “why” at
least once. Appropriate vocabulary has been incorporated in your answer.
60% -Your description is fairly complete; however the reader may still be able to ask you “how” or “why” at
least once. Not enough appropriate vocabulary has been incorporated in your answer.
40% -Your answer is on the right track but is underdeveloped in terms of explanations and use of appropriate
vocabulary.
20% - Your written work does not address the question that has been asked, but you wrote something down.
Practice 4 - Classical Genetics Utilizing Active Learning
The first activity for this unit is homework. The homework was given out during the last class period. It is a
series of questions the students must answer before coming to this class. They will be given a short quiz at the
beginning of this class period over these questions. The questions are designed in such a manner that students
must read the chapter if they are to successfully answer them. That is, the questions cannot be easily answered
by scanning the text looking for an exact answer. The students must read at least a majority of the chapter to
develop complete answers. I want the students to read the chapter before coming to class so that they will be
familiar with the material to be covered.
I normally start a lecture with a series of questions that are intended to get the students engaged, to focus on
26
today's subject, and that allow them to make connections between what they already know and what we are
discussing that today. The following is from a class on classical genetics.
Instructor: You know by now that I don't spend a lot of time talking about the biologists that have made
important contributions to our knowledge. It is not that I don't think they are important, because I do. It is
because there are so many things to cover this semester. I do want to spend a little time talking about a couple
of historically important biologists today. I want you to think critically about how the science of biology is
done, to be able to see how biologists think so that you can learn to think like one. Maybe you have come to
realize that this is part of the purpose of this course, to learn to think like a biologist. Who is the father of
classical genetics?
Student: Gregor Mendel
Instructor: When did Mendel do his work?
Answer: 1860’s
Instructor: Who else did biology research in the 1860’s?
Answer:
Instructor: The reason I mention that is that, unfortunately Darwin and Mendel never met, they never knew
about each other. Darwin lived where?
Answer: England
Instructor: Mendel lived where?
Answer: Austria
Instructor: Mendel was a monk, so where did he live in Austria?
Answer: a convent
Instructor: Not exactly, what is the male equivalent of a convent?
Answer: a monastery
Instructor: Right. My point is Mendel lived a relatively isolated existence. Isolated from other biologists.
Isolated because of geography and isolated because of lack of communication. Part of what makes what
Mendel did amazing is that no one completely understood what he was doing. He spent years working on
something that no one else really understood. Can you imagine spending years working on something that no
one else understood? Do give you an idea of how misunderstood he was, when he died, his brother burned his
papers. Mendel's brother loved him, he did it because he loved his brother and he didn't want people to think he
was crazy.
So if his brother burned Mendel's work how do we know about him now?
Answer: Cause he saved things or sent them to someone.
Instructor: Right, fortunately Mendel wrote several papers and sent them to the Royal Society of London, the
scientific society of the time. Do you know what happened when they read Mendel's papers?
27
Answer: They didn't understand it?
Instructor: Right, no one within the Royal Society understood Mendel's work. They saved it, but no one,
including Darwin, understood it. To get this in context you must understand that at the time the words
chromosome and gene didn't exist and no one knew how traits where inherited until years later. Now we say
that Mendel discovered alternative versions of genes. What is wrong with saying that?
Answer: Mendel didn't know about genes, therefore he must have discovered alternative versions of inheritable
traits.
Instructor: (Drawing a sperm with a little person inside the head of the sperm) To give you an idea of the
knowledge of genetics at the time there where drawings in biology books like this. What is wrong with this
drawing?
Answer: There is not a person inside a sperm?
Instructor: What is in the head of a sperm?
Answer: Chomosomes. Genes.
Instructor: How many?
Answer: One set, or one half the number that would be in a human. You need another set from a mother to
make a whole person.
Instructor: Obviously there were a number of things people did not understand about inheritance at the time.
Just think: Mendel started with very little knowledge, worked for years in isolation from other biologists, never
got any recognition during his lifetime. Imagine spending your adult life doing something that no one else
understood. But he was lucky in one thing. That is, he was lucky in the organism he worked with. What
organism did he study?
Answer: Pea plants.
Instructor: Right. The reason I say he was lucky is that all the visible traits in pea plants are inherited in an easy
to see and easy to understand dominant - recessive manner. Just to give you an idea of how lucky he was, do
know what a hydrangea plant looks like? There is a photo of one in the back of the genetics chapter. For those
of you that read the chapter, the color of hydrangea flowers is determined not by genes, but by what?
Answer: pH of the soil.
Instructor: Now imagine if Mendel had looked at something like hydrangeas.
Instructor: What does P stand for in "P generation"?
Answer: Parents
Instructor: What is the F1 generation?
Answer: The offspring of the P generation.
28
Instructor: So if you were the F1 generation, who would the F2 be?
Answer: My kids.
Instructor: So who would the P generation be?
Answer: My parents.
Instructor: What are alternative versions of genes?
Answer: Brown eyes, blue eyes…
Instructor: What genetic disorder is more common in males than females?
Answer: Color blindness
Instructor: What is independent assortment?
Answer: Where chromosomes can go either way during anaphase of meiosis 1 or meiosis 2
Instructor: What is phenotype?
Answer: What an individual looks like as a result of his or her genes.
Instructor: What is genotype?
Answer: What your genes look like.
Instructor: What is a zygote?
Answer: A fertilized egg.
Lecture continues.
Practice 5 - Properties of Water
In this Activity you will investigate some of the physical properties of water. If you need more information a
more thorough discussion of water's characteristics can be found in your textbook.
HYDROGEN BONDS When two hydrogen atoms react with an oxygen atom to form water, there is an
unequal sharing of electrons among the atoms. This creates a slightly negative charge on the side of the water
molecule that has more of the electron cloud. Water molecules act like a bunch of magnets holding on to each
other by the attractions between the + and - ends. The force created by those attractions is called a "hydrogen
bond", and it is the secret to all of water's special properties.
QUESTIONS
1. As water falls from the clouds, what force keeps the water in drops? (This force is sometimes called the
cohesion of a substance.)
The force is cohesion. It is due to the attraction of the positively charged hydrogen of one water molecule for
the negatively charged oxygen of another.
29
2. In order for the liquid water to evaporate and become steam, heat must be added. In a pan of boiling water,
what bond is being broken by the heat of the stove?
Hydrogen bonds
3. So, if heat is required to evaporate water, then what is released when water condenses?
energy
4. On a calm, but rainy day, the temperature rises slightly when it starts to rain. Explain.
As it begins to rain many water molecules are changing from the vapor state to a liquid. As they change from
one state to the next they are forming hydrogen bonds. When hydrogen bonds form between water molecules
energy is released in the form of heat.
WATER ADHESION Adhesion occurs when two or more different substances are stuck together as if by glue.
Water has some interesting adhesion properties.
GO GET:
1. A small container of water.
2. An eyedropper.
3. Four microscope slides.
NOW:
1. Put several drops of water on one slide, then place the other slide directly on top of the wet slide.2. Try to pull
apart the glass slides without sliding them past each other.
3. Repeat this experiment with the two dry slides.
QUESTIONS:
1. How strong is the force of attraction between the two dry slides?
Not very strong
2. How strong is the force of attraction between the two wet slides?
It is fairly strong.
3. What is the name of the force that holds the two slides together?
Adhesion, it is due to the attraction between water molecules.
4. A freeze-dried anchovy is fairly easy to break between your fingers. Yet, when the fish is allowed to sit in
water for a while, it will only bend with the same effort. Explain.
A freeze-dried anchovy has had all of its water removed and is therefore easier to break. One of water’s many
functions is to help hold a living organism together due to the attraction of water molecules to other negatively
and positively charged substances.
5. Based on your answer to #4, what is one important role of water in living organisms?
See second sentence in answer to #4.
30
CAPILLARITY
GO GET:
1. A glass capillary tube.
2. A small beaker of water.
NOW: Hold the capillary tube vertically between your fingers, and put the bottom end just below the surface of
the water. The process you have just observed is called capillarity.
QUESTIONS:
1. What happened when you did this experiment?
The water rose up the capillary tube.
2. Draw a simple sketch of the results.
The sketch should illustrate a beaker with some water and the capillary tube. The water in the capillary tube
should be higher than the water level in the beaker.
3. Explain your results. What is it about water that makes it do this? (Be specific about the forces of
attraction.)
The water moved up the capillary tube because of the force of capillary action. Capillary action occurs because
as water molecules move into the tube they “pull” other water molecules in due to the attractions between
water molecules.
4. Why do you think this property of water would be important to plants?
Plants must have water for photosynthesis. Because photosynthesis usually occurs in the upper parts of the
plant, in the leaves, water must rise from the roots to the leaves. Capillarity allows water to move up into the
higher regions of a plant.
HEATING PROPERTIES OF WATER The ease or difficulty of heating water will tell us something about
the strength of the hydrogen bonds and the temperature stabilizing role of water within living organisms. The
rate of temperature increase of a substance (like water) depends on how easy it is for heat energy to increase the
speed of molecular motion in that substance. If it doesn't require much heat to increase the motion, then we say
that the substance is "easy to heat up." When we apply this idea to the heating of water, it means that we will be
able to answer the question: "Are the hydrogen bonds between water molecules strong enough to make water a
substance that is hard to heat up?"
GO GET:
1. A hot plate.
2. A chunk of steel.
3. A beaker (the 100-ml size is best).
4. A container of water.
NOW:
The cooling rate of an object is directly related to the amount of energy absorbed by that object. If an object
cools quickly, then it didn't have much heat energy to start with.
31
1. Weigh the piece of steel.
2. Put an amount of water equal to the weight of the steel object into the beaker.
3. Put the piece of steel into the water, and heat the container until it just begins to steam.
4. Immediately remove the piece of steel from the beaker, and put both the beaker of water and the piece of steel
onto the table. (Your results will be more accurate if you pour the hot water into a cool beaker at the same time
you put the steel on the table.)
5. Repeatedly touch both the water and the piece of steel until both are approximately the same temperature.
Keep track of how long it takes for each to cool.
Time for the water to cool = about 4 minutes
Time for the steel to cool = about 2.5 minutes
QUESTIONS:
1. Which substance cooled the slowest? (circle your choice)
the water should be circled
Steel
Water
2. Which substance would require more heat energy to heat it up? Remember that the amount of heat given off
by a substance equals the amount of heat absorbed by that substance when it was heated. (circle your choice)
the water should be circled
Steel
Water
3. We know that sitting in 70 degrees F water is more chilling to the body than sitting in room air at 70 degrees
F. Explain why.
The water would be more chilling because there are more water molecules in the bathtub than in the
surrounding air. As hydrogen bonds are forming they “pull” energy, in the form of heat, from their
surrounding environment. Your body temperature is higher than 70 degrees F, therefore the water gets energy
from you to form hydrogen bonds.
If you were made of steel, would it be more chilling or not? Explain.
It would be more chilling because steel does not form hydrogen bonds between its atoms. Hydrogen bonds help
living organisms maintain their body temperature.
4. Based on your experimental results, what do you conclude about the importance of the hydrogen bond on the
heating up of water?
It takes more energy to heat up water because water is held together by hydrogen bonds, but conversely, water
looses heat more slowly because of the hydrogen bonds. The hydrogen bonds between water molecules help
living organisms maintain the body temperature.
5. Is water a temperature-stabilizing substance for living organisms?
Yes, see answer to #4 above.
EVAPORATION OF WATER The heat of vaporization is the amount of heat energy required to vaporize a
substance (like water). We can estimate the heat of vaporization for water by comparing that process with what
32
we saw in the previous experiment.
GO GET:
1. A hot plate.
2. Three equal-size beakers (the 250-ml size is best).
3. A thermometer. Be careful, please! This equipment is fragile.
NOW:
1. Using the information below #4 label three beakers and fill each one with the indicated amont of water. Put
Beakers A and B in the freezer to stay cold.
2. Prepare a large container of boiling water. Using the special measuring pipettes for safety remove 10 ml of
boiling water and place in beaker C.
3. Preheat your hot plate at a setting that you will know will boil water moderately. (not the highest setting!)
4. Place all 3 beakers on your hot plate. It is important that you start all three beakers at exactly the same time,
without time for the beakers to change temperature before heating on the hot plate. Record the starting time as
soon as all beakers are on the hot plate.
Beaker A
100 ml of ice cold water
Beaker B
10 ml of ice cold water
Beaker C
10 ml of boiling hot water
5. There are three events that you must record during this experiment.
a. How much time does it take Beaker B to just start to form little bubbles at the bottom? ______________
minutes.
b. How much time does it take for all of the water in Beaker C to boil away?
______________ minutes.
c. What is the exact temperature of the water in Beaker A when all of the water finally boiled out of Beaker C?
(Subtract the starting temperature if it was above 0 degrees C.)
_____________ minutes.
QUESTIONS:
1. What takes more energy? (circle your choice)
the second choice should be circled
To heat 10 ml of water
from 0 to 100 degrees C
or
To boil away (evaporate) 10 ml of water
that is already at boiling temperature (100 degrees C)
2. Based on your results, how effective is the evaporation of water (sweating) at removing excess heat from
your body?
Very effective
For the following 3 questions: Answers vary but the numbers should indicate it takes more energy for water to
evaporate than to simply get hotter. Students should relate that to the fact that it takes a significant amount of
energy to break hydrogen bonds as water is changing from a liquid to a gas.
3. We can calculate the actual number of calories of heat required to evaporate the 10 ml of water by examining
the results of Beaker A. A calorie is the amount of heat required to increase the temperature of 1 ml of water 1
33
degrees C. Beaker C had 10 ml of water boiled away. And during that same time, the 100 ml of water in
Beaker A increased by _______________ degrees C.
4. How many calories of heat were required to evaporate the 10 ml of water in Beaker C? (Remember: You
must consider both how much water is in Beaker A and how much its temperature increased while Beaker C
boiled away.)
_____________ calories.
5. So, how many calories would be required to evaporate only 1 ml of water?
_____________ calories.
6.What does this exercise tell you about calories, exercise, and sweating?
As you exercise your body temperature increases. Some of that heat can be released as water molecules leave
your body.
Practice 6 - What the Heck is pH?
HYDROGEN IONS An ion is an atom that has lost or gained electrons, and thereby has become electrically
charged (either + or -). They act differently than uncharged atoms. (It's like comparing magnets with nonmagnets.)
These ions are very important in out life processes, and we would die without them. Table salt is an example of
two essential ions -- sodium and chloride.
Of all the ions in your body, none is more important than the hydrogen ion, H+. The term "pH" refers to the
concentration of H+ ions in water. Biologists are interested in H+ concentration because it affects chemical
reactions so greatly.
A small change in this ion can dramatically affect life. Acid rain and stomach acid are two expressions of the
concentration of H+ ions. Also, the blood of a human is so sensitive to H+ concentration that a small pH
change from your normal of 7.4 can result in your death.
We monitor the pH of our fish aquariums and our swimming pools in order to avoid potential problems. In the
case of the aquarium, we are trying to maintain a good environment for micro-organisms, whereas, in the
swimming pool, we are trying to prevent micro-organisms from growing.
QUESTIONS:
1. Knowing how important pH can be to living organisms, what would be the effect of acid rain on the
ecosystem?
It can have devastating effects on organisms, especially aquatic organisms. There are many bodies of water
that are now biologically dead due to low pH as a result of acid rain.
2. What does the "p" stand for in pH?
Potential, it is the potential of hydrogen.
The pH scale ranges from 1 to 14. Each step up the pH scale means that there is 10x more OH- (base) and less
H+ (acid) than the step below.
34
Each step down the pH scale means that there is 10x more H+ (acid) and 10x less OH- (base) than the step
above.
A water solution with a pH of 7 is neutral because the concentration of the H+ ions (acid) is equal to the
concentration of the OH- ions (base).
If the pH is less than 7, then there are more H+ (acid) ions than OH- (base) ions, and the solutions is called an
acid.
If the pH is more than 7, then there are more OH- (base) ions than H+ (acid) ions, and the solution is called a
base.
QUESTIONS:
1. pH is a measure of hydrogen ion concentration.
2. A pH of 3 would be an acid or a base?
an acid
3. A pH of 11 would an acid or a base?
A base
4. What is the relationship between H+ and OH- at a pH of 7?
H+ should equal OH5. How much more H+ is in water at a pH of 3 when compared to a pH of 6?
Water with a pH of 3 is 1000 times more acidic than water with a pH of 6.
6. How much more OH- is in water at a pH of 11 when compared to a pH of 7?
Water with a pH of 11 is 10,000 times more basic than water with a pH of 7.
HOW TO MEASURE PH
The pH can be measured with a machine or with special color indicators. A pH machine directly reads the H+
concentration and displays the pH on a screen. A color indicator is a special molecule that changes color at a
particular pH level.
We will use the second technique -- pH color indicators --because they are a lot cheaper than the machine.
GO GET:
A pH paper test kit.
NOW:
1. Use the pH paper test kit to determine the pH of the three unknown solutions on the demonstrations table.
2. Dip a separate pH test strip into the 3 solutions.
35
QUESTIONS:
1. Is solution A acid or base or neutral? Neutral, the pH is 7.
2. Is solution B acid or base or neutral? Acidic, the pH is 4.
3. Is solution C acid or base or neutral? Basic, the pH is 11.
BUFFERS A buffer is a chemical substance that can be added to water, and will make that solution resist a pH
change.
GO GET:
1. 25 ml of Sample X in a small beaker.
2. 25 ml of Sample Y in a small beaker.
3. A dropper - bottle of phenol red.
4. A dropper - bottle of acid.
NOW:
1. Put 5 drops of phenol red into each beaker. Phenol red is a pH color indicator. It turns yellow in acid, and
it turns red in base.
2. While counting the drops, add acid one drop at a time until each beaker turns yellow. Gently shake the
beakers after each drop in order to mix the acid into the test solution.
QUESTIONS:
1. Which solution contains a buffer, Sample X or Sample Y.
Sample X contains the buffer because it took more drops of acid to change its pH.
2. How many more drops of acid did it take to change the buffered solution yellow?
15 – 20 more drops
3. Why do you think that one of the brands of aspirin is called Bufferin?
Aspirin
Reflections
During the last year we have been exposed to critical thinking from a number of viewpoints; and not many of
those viewpoints have been those of a scientist. I have found that to be most helpful in discussing and
explaining what critical thinking is with my students, most of who are not, nor will ever be scientists. It has
given me a whole new set of words to use while explaining critical thinking. I will still use the scientific
method, but I will also use some of my new vocabulary to try to appeal to as many different students as
possible.
My participation in the FLC has also forced me to look at what I do everyday in my classroom. It has
reminded me that good teaching is an evolutionary process. I have gotten complacent. Now I have critically
looked at the labs I use, the tests I give, the homework, everything. I certainly will not change everything, but I
have already made several significant changes and I will do more next semester.
36
One last thought. As a college we don't do much to promote collaborative discussions among our faculty.
Many of our faculty members have some great ideas on how to improve teaching and student learning. One of
the greatest, an unexpected, benefits of the FLC to me has been the spontaneous discussions that sometimes
happen during our weekly sessions, as well as the emails that sometimes follow. Teaching is a very inexact art
and very few of us ever get it exactly right. The more time we take to discuss teaching strategies with our
colleagues the better off we, as a faculty and a college, will be.
37