Microsoft Word - Unit.Plan_Supporting.Docs.docDAY 1
Anticipation Guide:
Read the five statements below. Determine whether each statement is true or false.
1. By law, a pesticides is “any substance or mixture of substances
intended for preventing, destroying, repelling, or mitigating insects,
only”
2. Pesticides are among the only toxic substances purposefully applied to
the environment.
3. Pesticides completely solve pest problems, so that pests do not come
back again.
4. There are over 500 different pesticides and over 1,000 products
currently registered for use in the U.S.
5. Each year, about 4.4 billion applications are made in homes, yards,
and gardens, alone.
After you receive the article, check your answers. Next to each question, identify the paragraph number that the answer came from. For each answer
that is false, correct the statement to make it true.
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
The Stockholm Convention is an international legally binding agreement on persistent
organic pollutants (POPs). POPs are defined by the United Nations Environment Programme as
“chemical substances that persist in the environment, bioaccumulate through the food web, and
pose a risk of causing adverse effects to human health and the environment.” The negotiations
for the Stockholm Convention on POPs were completed on May 23, 2001 in Stockholm
Sweden. The convention entered into force on May 17, 2004 with ratification by an initial 128
parties and 151 signatories. These signatories agreed to outlaw nine of the “dirty dozen”
chemicals, limit the use of DDT to malaria control, and curtail inadvertent production of dioxins
and furans. Parties to the convention have agreed to a process by which persistent toxic
compounds can be reviewed and added to the convention, if they meet certain criteria for
persistence, pose a transboundary threat and are toxic to wildlife and humans.
Your Task:
Since parties of the Stockholm Convention have agreed to monitor currently used pesticides,
your task is to research your pesticide and create a proposal for the review panel. In this
proposal, you will characterize your pesticide and come to a consensus within your group on a
recommendation for the Convention. Your proposal can be in the form of a video, science poster
or formal paper.
3. How does your pesticide work?
4. What is the chemical structure of your pesticide?
5. What is the vapor pressure of your pesticide?
6. What is the solubility of your pesticide?
7. Where is your pesticide used?
8. Does your pesticide bioaccumulate and/or biomagnify?
9. Is your pesticide toxic to wildlife and/or humans?
10. What is your recommendation for the Stockholm Convention?
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
CATEGORY Excellent Proficient Making Progress Needs Improvement
Research Group researched the
subject and integrated 7
or more "tidbits" from
their research into their
less "tidbits" into their
exceptionally well. All
members listened to,
shared with and
members. The group (all
AND/OR were overtly
the material being
clearly explain why they
felt the vocabulary, audio
and graphics they chose
vocabulary, audio and
the students can describe
element relate to the
the proposal seem only
the purpose of the proposal.
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
WHY?
Over the past several years there has been much discussion about the negative effects of ozone. However,
the creation of ozone is necessary for the production of OH radical.
This molecule acts as a detergent in the atmosphere. In fact, it is the key molecule that interacts with
pesticides in the atmosphere to degrade them. Keep in mind that ozone occurs in two different layers of
the atmosphere — the _______________ and the ____________________. The stratospheric ozone, the
so-called ________ ozone, protects the planet from the harmful effects of the sun's
____________________ rays. The tropospheric ozone interacts with UV-B and water vapor to form OH
radical.
About 90% of all ozone is found in the stratosphere, where it plays an important role by
_______________ harmful UV radiation. Some of the chemical pollutants that we are releasing into the
atmosphere are destroying the ozone in this layer. It is the destruction of this stratospheric ozone, the
subsequent formation of the __________________, and the general global reduction in stratospheric
ozone thickness that should cause grave concern among all people. Additionally, without ozone, the
concentration of the “detergent,” OH, will in turn decrease. For this reason, investigating the reactions of
ozone in the atmosphere is of utmost importance.
INFORMATION
The amount of ozone in the stratosphere is the _______ result of production and loss processes. Ozone is
produced by ________________ (breaking apart of molecules by light) of oxygen high in the stratosphere
where ultraviolet light is most ________. Ozone is lost by conversion back to molecular oxygen (_____)
through reactions whose net effect is: (Balance the reaction).
____ O + ____ -----> ____
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
So in the stratosphere, ozone is always being __________ and _____________. Normally, this natural
cycle is in perfect _____________. It keeps just the right amount of ozone in the ozone layer.
With the discovery of the "ozone hole" over _______________ in 1985, scientists determined that
something was destroying ozone faster than nature could replace it. This something, a group of human-
produced chemicals called ___________________________ (CFCs), has shifted the balance in the
natural process of ozone production and ozone destruction. CFCs _____________, or speed the break up
of, ozone molecules when _______ rays are also present. One CFC molecule can help destroy up to
____________ ozone molecules over its lifetime of ________ years, and ozone production cannot keep
up. In the graphic on the following page, the destructive cycle of a chlorine atom is shown.
1. UV radiation breaks off a _________
atom from a CFC molecule.
2. The chlorine atom attacks an
__________molecule ( ), breaking it
3. The result is an ordinary oxygen
molecule (_____) and a chlorine monoxide
molecule (______).
is attacked by a free oxygen atom
releasing the chlorine atom and forming an
ordinary oxygen molecule ( ).
attack and destroy another ozone molecule
( ). One chlorine atom can repeat this
destructive cycle __________ of times.
Background
Ozone, a molecule containing three oxygen atoms, is made when UV light breaks the bonds of
oxygen molecules containing two oxygen atoms in the stratosphere. The single oxygen atom is
highly reactive and bonds with another oxygen molecule creating ozone. As students, you will
play the roles of various atoms and molecules, to make the ideas of basic chemistry in the
atmosphere more concrete. This activity illustrates the chemical reactions involved in the
photochemistry of ozone production and destruction, along with a catalyst that affects the rate of
the reaction.
Part 1: Modeling Oxygen in the Earth's Atmosphere
1. Let 5 or 6 pairs of students represent oxygen molecules. Each student should construct a
sign using a piece of paper, writing a large O on it and to indicate they are oxygen atoms.
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
2. Students in each pair should hold hands to simulate the bonding between the atoms of
oxygen in each molecule. Have these pairs of students move about in a cleared area in the
classroom to simulate molecular motion. It is appropriate for them to bounce off a wall or
collide with each other as they move about. After moving about for a minute or so, stop
to discuss what has been demonstrated.
Questions and Observations
1. How are the moving pairs of students similar to what occurs in the air in the room?
2. How is it different?
3. What could be done to make the analogy better?
4. What is oxygen called if it has two atoms per molecule?
Part 2: Simulating the Formation of Ozone in the Stratosphere
1. Repeat the steps under modeling the earth's oxygen, but this time darken or dim the lights
in the room.
2. Add a student who, with a flashlight, simulates solar radiation. Place a clear purple
plastic sheet over the lens of the flashlight to represent the ultraviolet short wavelengths
that are involved in the breakup of diatomic oxygen.
3. Let pairs of students representing oxygen begin their motion as before. When the student
with the flashlight shines the light on a pair of students, the bond between them breaks,
and students let go of their partner.
Using Lewis dot structures, draw a
picture to represent O2:
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
4. As the motion continues, these single atoms of oxygen move around until they bump into
a pair of oxygen atoms. Each of the single oxygen atoms combines with the pair they
bump into, forming a group of three oxygen atoms. These three students hold hands,
representing a molecule of ozone.
Questions and Observations
1. How is this simulation similar to the way ozone is formed in the stratosphere?
2. What is oxygen with three atoms per molecule called?
3. How many molecules of ozone can be formed by the breakup of one molecule of
diatomic oxygen by ultraviolet light?
4. Why is ozone formed this way in the stratosphere and not in the air near the earth's
surface?
Part 3: Demonstrating How Ozone Breaks Down in the Stratosphere
1. Have several groups of three students, each representing ozone, move about the room.
Pairs of students representing diatomic oxygen can be added as a touch of realism.
2. This time the lens of the flashlight should be covered with clear red plastic to represent
UV light of a longer wavelength.
3. When this light is used to illuminate an ozone molecule, the ozone breaks up to form a
diatomic molecule (a pair of students) and an oxygen atom (single student).
4. This process is repeated by shining the light on a second ozone molecule, producing
another pair of oxygen atoms and another single oxygen atom.
5. The two single oxygen atoms should then combine to form a pair of atoms, or a molecule
of diatomic oxygen.
O3:
Questions and Observations
1. How many molecules of diatomic oxygen are formed from the breakup of two molecules
of ozone?
2. How is the breakup of ozone in the stratosphere similar to its formation there?
Part 4: An Example of a Chemical that Speeds up the Breakdown of Ozone
Of all the chemicals involved in the breakdown of stratospheric ozone, none have received more
attention than the chlorofluorocarbons, or CFCs. The two most common are CFC-11 ( ) and
CFC-12 ( ). These compounds can be modeled by letting students represent atoms of
carbon (C), chlorine (Cl), and fluorine (F). For example, a molecule of CFC-11 would be
composed of one student representing a carbon atom, another representing a fluorine atom, and
three students representing three chlorine atoms. The students should hold hands to demonstrate
how atoms are bonded in a molecule.
Graphic of the molecular structure of common CFCs
Questions and Observations
1. The CFCs are inert, that is, they do not react with other materials under most conditions.
How can this be demonstrated using groups of students to represent atoms of different
elements?
2. The CFCs that enter the atmosphere at the earth's surface have found their way into the
stratosphere. How can this be demonstrated using students to play the role of various
gases in the air?
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
Part 5: The Role of Chlorine in the Breakdown of Ozone in the Stratosphere
UV light breaks down CFCs in the stratosphere, releasing chlorine atoms. This can be
demonstrated by having a student with a flashlight shine a light on a group of students
representing a molecule of CFC-11 or CFC-12. Let one student representing a freed chlorine
atom move amidst groups of students representing ozone. The chlorine is involved in the
breakdown of ozone as follows:
Cl + ----> ClO +
ClO + O ----> Cl +
1. A student representing chlorine pulls an oxygen atom away from an ozone molecule to
form chloride oxide (ClO).
2. The two students representing ClO react with an oxygen atom.
3. The two students representing oxygen combine to form an oxygen molecule.
4. The student representing chlorine is then free to attack another molecule of oxygen.
5. Repeat these steps several times to show the chain reaction.
Questions and Observations
1. What is a catalyst?
2. Does the chlorine act as a catalyst in this reaction? How do you know?
3. Why is the involvement of chlorine in the breakdown of ozone called a chain reaction?
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
From Scholastic Online
January 1, 1999
Contaminating the Arctic
Our perception of the Arctic region is that its distance from industrial centers keeps it pristine
and clear from the impact of pollution. However, through a process known as transboundary
pollution, the Arctic is the recipient of contaminants whose sources are thousands of miles away.
Large quantities of pollutants pour into our atmosphere, as well as our lakes, rivers, and oceans
on a daily basis. In the last 20 years, scientists have detected an increasing variety of toxic
contaminants in the North, including pesticides from agriculture, chemicals and heavy metals
from industry, and even radioactive fall-out from Chernobyl. These are substances that have
invaded ecosystems virtually worldwide, but they are especially worrisome in the Arctic.
Originally, Arctic contamination was largely blamed on chemical leaks, and these leaks were
thought to be "small and localized." The consensus now is that pollutants from around the world
are being carried north by rivers, ocean currents, and atmospheric circulation. Due to extreme
conditions in the Arctic, including reduced sunlight, extensive ice cover and cold temperatures,
contaminants break down much more slowly than in warmer climates. Contaminants can become
highly concentrated due to their significantly lengthened life span in the Arctic.
Problems of spring run-off into coastal waters during the growth period of marine life is a critical
concern. Spring algae blooms easily, absorbing the concentrated contaminants released by spring
melting. These algae are in turn eaten by zoo plankton and a wide variety of marine life. The
accumulation of these contaminants increases with each step of the food chain or web and can
potentially affect northerners who eat marine mammals near the top of the food chain. Pollutants
respect no borders; transboundary pollution is the movement of contaminants across political
borders, whether by air, rivers, or ocean currents. The eight Circumpolar nations, led by the
Finnish Initiative of 1989, established the Arctic Environmental Protection Strategy (AEPS) in
which participants have agreed to develop an Arctic Monitoring and Assessment Program
(AMAP). AMAP establishes an international scientific network to monitor the current condition
of the Arctic with respect to specific contaminants. This monitoring program is extremely
important because it will give a scientific basis for understanding the scope of the problem.
Arctic Haze
In the 1950's, pilots traveling on weather reconnaissance flights in the Canadian high Arctic,
reported seeing bands of haze in the springtime in the Arctic region. It was during this time that
the term "Arctic haze" was first used, referring to this smog of unknown origin. But it was not
until 1972, that Dr. Glenn Shaw of the Geophysical Institute at the University of Alaska first put
forth ideas of the nature and long-range origin of Arctic haze. The idea that the source was long
range was very difficult for many to support.
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
Each winter, cold dense air settles over the Arctic. In the darkness, the Arctic seems to become
more and more polluted by a buildup of mid-latitude emissions from fossil fuel combustion,
smelting and other industrial processes. By late winter, the Arctic is covered by a layer of this
haze the size of the continent of Africa. When the spring light arrives in the Arctic, there is a
smog-like haze which makes the region, at times, looks like pollution over such cities as Los
Angeles.
This polluted air is a well-known and well-characterized feature of the late winter Arctic
environment. In the North American Arctic, episodes of brown or black snow have been traced
to continental storm tracks that deliver gaseous and particulate-associated contaminants from
Asian deserts and agricultural areas. It is now known that the contaminants originate largely
from Europe and Asia.
Arctic haze has been studied most extensively in Point Barrow, Alaska, across the Canadian
Arctic and in Svalbard (Norway). Evidence from ice cores drilled from the ice sheet of
Greenland indicates that these haze particles were not always present in the Arctic, but began to
appear only in the last century. The Arctic haze particles appear to be similar to smog particles
observed in industrial areas farther south, consisting mostly of sulfates mixed with particles of
carbon. It is believed the particles are formed when gaseous sulfur dioxide produced by burning
sulfur-bearing coal is irradiated by sunlight and oxidized to sulfate, a process catalyzed by trace
elements in the air. These sulfate particles or droplets of sulfuric acid quickly capture the carbon
particles which are also floating in the air. Pure sulfate particles or droplets are colorless, so it is
believed the darkness of the haze is caused by the mixed-in carbon particles.
The impact of the haze on Arctic ecosystems, as well as the global environment, has not been
adequately researched. The pollutants have been studied in their aerosol form over the Arctic.
However, little is known about what eventually happens to them. It is known that they are
removed somehow. There is a good degree of likelihood that the contaminants end up in the
ocean, likely into the North Atlantic, Norwegian Sea and possibly the Bering Sea — all three
very important fisheries.
Currently, the major issue among researchers is to understand the impact of Arctic haze on
global climate change. The contaminants absorb sunlight and, in turn, heat up the atmosphere.
The global impact of this is currently unknown but the implications are quite powerful.
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
WHY?
place on Earth. Where would that be? If you
chose a far away location, like the Arctic, you
have the same misconception that many other
people have. Although there are no factories,
no cars and no farms in the Arctic, these areas
are often those the most susceptible to
pollution. So the next time you choose your
bottle of water, you might choose to stay away
from water from this region. In this exercise
you will analyze the environment of the Arctic
to determine if you want to drink glacial
water.
process known as transboundary pollution.
The makes this region the recipient of
contaminants whose sources are thousands of
miles away. Large quantities of pollutants
pour into our atmosphere, as well as our lakes, rivers, and oceans on a daily basis. In the last 20
years, scientists have detected an increasing variety of toxic contaminants in the North, including
pesticides from agriculture, chemicals and heavy metals from industry, and even radioactive fall-
out from Chernobyl. These are substances that have invaded ecosystems virtually worldwide, but
they are especially worrisome in the Arctic.
Success Criteria:
• Summarize the process by which atmospheric pollutants reach the Arctic
• Interpret graphs to analyze the concentration of pesticides
• Investigate transport of pesticides to the Arctic
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
Pesticides are toxic chemicals that are deliberately released into the environment in large
quantities. Although they are supposed to kill target organisms, the excess can be released into
the environment and transported in a number of ways.
Figure 1. The Pesticide Cycle
Key Questions:
1. Based on Figure 1, name three ways that pesticides might stay in the environment and
explain where they go.
2. Based on Figure 1, explain two ways that pesticides might be degraded in the
environment.
3. Based on Figure 2, why might the Arctic receive pollutants?
4. Based on Figure 2, explain how pesticides can be deposited so that they end up in the
food chain.
Exercises:
1. Based on these two figures, what is meant by the term “long range atmospheric
transport”?
2
Key Questions:
which (2) are comparatively more
likely to be found in the air?
5. Which compounds (2) are most
likely to be found in the tissues of
polar bears?
compounds would you predict to
find the most often in the Arctic?
Exercises
the air, they are being found in the
Arctic in high concentrations.
DDTs very dangerous?
between selected environmental compartments or
species of 6 organochlorine contaminants.
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
Model 3. Atmospheric Transport
Now that we know that some contaminants are often found in the air (due to their high vapor
pressure), we want to find out how these contaminants are reaching the Arctic. The figure below
demonstrates the dominant air currents on Earth.
Key Questions:
most of the Arctic contaminants coming
from?
throughout the globe?
Key Questions
found in highest concentrations?
concentration of beta-HCH than
4. How many grams are in on microgram?
5. What would you suggest about the usage of the pesticides? In other words, what
pesticide do you think is used most often? Why?
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
3. Is your pesticide being found in the Arctic?
4. Predict how your pesticide is getting to the Arctic.
5. Is your pesticide likely to be found in water and/or in organisms?
6. Should you drink glacial water as your bottled water of choice? Why or why not?
Problems
1. Sometimes scientists predict that pesticides will degrade extremely fast in the
environment. So fast, in fact, that they do not worry about their transport to the Arctic.
However, some of these chemicals are still being found in the Arctic. Predict why this
might be the case.
**Remember, that the key degradation reaction of pesticides is the oxidation by OH radical.
Also, OH radical needs UV-B rays and O3 to form. Additionally, you may wish to consider
vapor pressure and solubility.
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
1 2 3 Mark
vocabulary words in
vocabulary words
clear and partially
correctly.
and accurate
clear or of
DAY 4
Pesticide Lab/Demo
Objectives 1. The student will understand the definition of a pesticide.
2. They will recognize why pesticides are used.
3. The student will understand why certain pesticides are no longer used.
4. The student will be able to make a judgement about the use of pesticides.
5. The student will understand the nature of an enzyme.
Materials a variety of fresh fruits and vegetables
petri dishes
naphthalene
sewing needle
wood splints, cotton balls, paper, cotton cloth
Recommended Strategy
Preplanning 1. Display the fresh fruits and vegetables and the pesticide containers on the demonstration table.
2. Pour about 20 mL of the vegetable oil into a florence flask and label it "human body fat".
3. Pour about 20 mL of the water into a florence flask and label the flask H20.
4. Place a small amount of the naphthalene crystals into a petri dish and label the dish "DDT"".
5. Prepare the two small stuffed animals by labeling them as baby #1 and baby #2. Tape or sew
back the ears, arm, eyes, nose, etc. of #2.
6. Prepare the two plants by labeling them as plant #1 and plant #2. Remove the leaves from
plant #2.
Introduction Begin the demonstration by having the students observe the damaged vegetables/fruits/leaves.
Get some oral responses to the question, "what happened to this produce?" Have students circle
demo table to observe the fruit/vegetable display. Ask students if they can get the same or better
quality items near where they live. Relate quality and quantity of produce to pesticide use by
farmers. At this time you should point out the different types of pesticides that were brought in
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
the containers on the demo table. Briefly discuss pesticide use in relation to limited resources and
growing world populations. Tell students that chemists are constantly working to produce
pesticides that do not have negative effects on the environment.
Procedure 1. Discuss the pesticide classes: chlorinated hydrocarbons, defoliants and organophosphates in
this order. The student should record the class, name, helpful and harmful effects of a particular
pesticide on his data sheet.
2. Demonstrate the actions and effect of the pesticides by simulation. Below are some
simulations, which show actions and effect of some pesticides. Students should do each
simulation before the action or effect of the pesticide is covered in the discussion.
action/effect simulation a)how DDT builds up in the bodies drop a few of the naphthalene
of aquatic animals and plants crystals into a florence flask
mammals eat filled with 20 mL of water
b)how DDT builds up in toxic drop a few of the naphthalene
amounts in the fatty tissues of crystals into a florence flask
mammals filled with 20 mL of vegetable oil
c)to show the effect of defoliants use plant #1 and plant #2
on forest use cotton and cotton cloth
d)to show defoliant effect after a use wood splints and paper
second application (losses to industry)
e)to show birth defects caused by use baby #1 and baby #2
defoliants
inhibit the enzyme relax their arm muscles:then
acetylcholinesterase have them continuously
or 6 more times
3. At the end of the demo ask students the following questions:
On the basis of the data collected, decide if:
a) pesticides should continue to be used
b) pesticide use should be banned
c) chemists should continue working to develop pesticides that do not
produce negative effects on the environment.
**Give reasons for your answers.
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
Acetylcholinesterase
Why?
Right now there are thousands of enzymes doing work inside your body. Enzymes are
very important proteins that allow cells to carry out chemical reactions very quickly. These
biochemical reactions allow the cell to synthesize compounds or degrade them as needed. Since
enzymes are proteins, they are made from amino acids. When an enzyme is formed, an amino
acid polymer is synthesized comprised of between 100 and 1,000 amino acids in a specific and
unique order. The order of the amino acids within the chain give the enzyme its specific
function.
and key. The shape of the enzyme is extremely important
for the specificity and efficiency of enzyme action. The
substrate that the enzyme works on must fit into the
active site of the enzyme. Additionally, appropriate
intermolecular (weak) and covalent interactions must
occur so that the product can be formed. Specific factors
control the kinetics of these reactions.
Enzymes are essential for the appropriate functioning of systems in the body. When
enzymes do not operate appropriately, then systems of the body suffer. Sarin, also known as GB,
is a human-made chemical warfare agent classified as a nerve agent. Nerve agents are the most
toxic and rapidly acting of the known chemical warfare agents. Interestingly, they are similar to
organophosphate pesticides in terms of how they work and what kind of harmful effects they
cause. These chemical compounds act on a specific enzyme called acetylcholinesterase.
Success Criteria:
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
Model 1: Typical Reaction of Acetylcholine in the Active Site of Acetylcholinesterase
Key Questions:
1. What type of interaction is responsible for the association with acetylcholine with the
serine residue at the esteric site?
2. What type of chemical reaction is this?
Exercises:
1. Draw a curved arrow mechanism for the above acetylcholinesterase catalyzed reaction.
2. Why might acetylcholinesterase be necessary in this reaction? (i.e. what role does an
enzyme play in a chemical reaction?)
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
The nucleophilic hydroxyl group of the serine residue located at
the active site of AChE reacts with the phosphorus of the
organophosphate resulting in a covalently bound
organophosphate. The result is inactivation of the enzyme since
the hydroxyl group is no longer available to attack the
acetylcholine substrate. In the case of irreversible inhibitors, this
is referred to as suicide inhibition.
Key Questions
3. Is the structure of the organophosphate similar to that of the usual substrate,
acetylcholine? How is it similar or dissimilar?
4. How will this compound likely interact with the enzyme?
5. Why is a covalent link also called a suicide inhibition?
Exercises:
3. Explain what will happen to the concentration of acetylcholine in the cell when AChE is
inhibited. You may wish to use the diagram below to assist you.
General Structure of
Unit Plan Rachel Ruggirello
POP Goes the Pesticide
4. Based on your assessment, how do these pesticides affect the nervous system of
organisms?
5. Explain why these pesticides might still have toxic effects on warm-blooded organisms,
although they are intended to kill insect pests.
Model 3: Enzyme Kinetics
A) Activation Energy
6. How does an enzyme change the energy in a chemical reaction?
7. Why doesn’t the energy of the reactants or the energy of the products change?
Exercises:
6. Which statement about enzyme catalyzed reactions is NOT true?
A. enzymes form complexes with their substrates.
B. enzymes lower the activation energy for chemical reactions.
C. enzymes change the Keq for chemical reactions.
D. many enzymes change shape slightly when substrate binds.
E. reactions occur at the "active site" of enzymes, where a precise 3D orientation of
amino acids is an important feature of catalysis.
Explain your reasoning.