General Instructions for Coding DQC Responses
Responses to DQC questions can be grouped into three general categories; Informal, Mixed or
Scientific. These three categories encompass a wide range of reasoning abilities, but all three categories
are common among college students. The table below describes the general types of responses that
would be associated with each level of reasoning. In addition, the levels of reasoning are assigned a
numerical value for coding purposes. Codes 2-4 are used for responses that attempt to answer the
question, while codes 1a-1e are reserved for missing responses or those that provide no information
about student reasoning.
Code
4
3
2
1a
1b
1c
1d
1e
Level
Scale
Successful use of
other scales to
explain macroscopic
phenomena
Processes described
in terms appropriate
for that scale
Partially successful
attempts to connect
scales, but with some
inappropriate use of
macroscopic ideas at
other scales
Matter
Reactants and products described
as chemical substances
Accounts of processes describe
Principled
transformation of reactants into
reasoning
products in ways that conserve
atoms at the atomic-molecular
scale and mass at larger scales.
Less than completely successful
attempts to conserve matter.
Reactants and products described
as material kinds, but atoms not
Mixed
traced through chemical processes
reasoning
and matter-energy
transformations may be used as a
“fudge factor.)
No attempt to make
Material inputs or needs and
connections across
products or results are mentioned,
scales for questions
but not in ways that clearly
posed at
distinguish matter, energy, and
macroscopic scale
conditions.
Informal
Inappropriate use of
No indication that the student is
reasoning
macroscopic scale
reasoning about transformation of
ideas at other scales
matter: no account of how
material inputs are transformed
into results.
Missing data (e.g. responses or codes lost after exam was taken and coded)
Student did not reach question
Student skipped question
I don’t know or equivalent
Nonsense answer that is not responsive to question
Energy
Forms of energy are clearly
identified and distinguished
from forms of matter.
Energy transformation
described in ways consistent
with energy conservation.
Energy is recognized as a
distinct entity, but sometimes
in ways that do not clearly
distinguish energy from matter
(e.g., glucose, ATP) and/or
conditions (e.g., temperature).
Accounts fail to conserve
energy.
“Energy” used in an informal
sense as something that makes
events happen.
No clear distinction between
energy sources and other
needs or inputs.
These general ideas for coding above are applied to each individual question below to provide specific
details for how to code each question. Still, you will find that the specific coding rubric for each
question does not list every possible answer that you might see. In these cases, refer back to the general
rubric above, and try to be as objective as possible. You will undoubtedly find responses that don’t quite
fit a specific category, but seem to be in between. For these scenarios, we suggest that you assign a 2.5
or 3.5 code to the student.
Digestion/Biosynthesis Diagnostic Question Clusters– ANSWER KEY
The transfer of matter and energy within and between organisms is a complex process that is better understood by
identifying and tracing specific matter and energy entities. Digestion and Biosynthesis are two important topics in
Biology courses and have implications for organisms and ecosystems. Yet, many of the details are occurring at
the cellular level. Two parallel DQCs covering the topics of Digestion and Biosynthesis (BA & BB) are designed
to help decipher student reasoning about these topics, particularly related to their understanding of matter and
energy through these important processes.
Organization of questions in Digestion/Biosynthesis DQCs.
Biosynthesis Form A (BA)
2 Matter Items
COYOTE (1)
GIRLGROW (4)
Biosynthesis Form B (BB)
2 Matter Items
APPLEDIG (2)
COYOTE (3)
2 Energy Items
GRAPGLUC (3)
PEOPENER (2)
2 Energy Items
ENERGAIN (1)
PEOPENER (4)
1 Large Scale Cross Process Item
BIOFUEL (6)
1 Large Scale Cross Process Item
KLGSEASON (5)
1 Small Scale Cross Process Item
CARBPATHS (5)
1 Small Scale Cross Process Item
EATBREATHE (6)
Diagnostic Question Cluster Form BA– ANSWER KEY
Please answer the questions below as carefully and completely as you can.
COYOTE
1. Coyotes are primarily carnivores. Their bodies include many substances, including proteins in all their cells. What percent
of the carbon atoms in a coyote’s body were once in the following substances and locations? Fill in the blanks with the
appropriate percentages; you may use 0% in your response if you feel it is appropriate. The percentages will add up to more
than 100% if you think that the same carbon atoms could have gone through two or more of these places on their way to the
coyote.
100 % from CO2 that was used by plants for photosynthesis
100 % from animals that the coyote ate
0 % from CO2 that the coyotes inhaled
0 % from O2 that the coyotes inhaled
0 % from water that the coyotes drank (not including substances in the water)
0 % from soil nutrients that plants absorbed while growing
Please explain your answer.
Correct, Scientific Answer: Coyotes are carnivores, which means they obtain carbon atoms from other animals which are
their prey. The carbon atoms in the prey are digested, transported through the blood stream of the coyote and incorporated
into tissues. All of the carbon atoms in the prey of the coyote were once carbon dioxide in the atmosphere that was utilized by
plants for photosynthesis. Animals in lower trophic levels ate the plants, and the animals were consumed by the coyote.
Coyotes do not obtain biomass by breathing CO2. Oxygen gas is a reactant in cellular respiration, but the oxygen atoms
leave the body in water and carbon dioxide molecules and are not incorporated into the coyote’s body. Water and soil
nutrients do not contain carbon, thus the final two answers should be 0%.
Processes = Digestion/Biosynthesis, Respiration, Principles = Matter, Scale, Scale = Organismal -> Atomic/Molecular
Purpose of Question: This question assesses whether students can account for the source of the matter in a secondary
consumer’s body. The question requires that students understand that carnivores do not eat plants, that they get the majority
of their mass from eating other animals, that they do not assimilate inhaled CO 2, and that coyotes intake oxygen and water,
but that these molecules do not contain carbon atoms. Exception: there may be a small amount of carbon contained in the
water they drink.
Coding Rubric
Code
Example Student Responses
4 - Scientific
-90,90,0,5,5,0
3 - Mixed
2 - Informal
-70,40,30,20,10,20
-60,20,0,0,10,10: I believe the majority of the
CO2 from the coyote’s body was stored in the
plants, and some Co2 is from the animals the
coyote ate, who ate the plants.
-5, 25, 50,50, 75,10: Coyotes along with all other
animals need a lot of water and is one of the most
important nutrients. The oxygen needed is also
very important and the Co2 exhaled will split the
amount of O2 the coyote takes in.
Description
Student writes greater than or equal to 75% for both of
the first two spaces (A. CO2 used by plants and B.
animals that the coyote ate) and writes less than 10%
for the other four spaces.
Answers for the first two spaces sum to greater than
60%, but remaining criteria from Code 3 description
are not met.
Answers for the first two spaces sum to less than 60%
PEOPENER
2. People need energy to live and grow. Which of the following is/are energy source(s) for people? Circle Yes or No for each
of the following and explain your answers.
a. Water
YES
NO
b. Food
YES
NO
c. Nutrients
YES
NO
d. Exercise
YES
NO
e. Sunlight
YES
NO
f. Carbon Dioxide
YES
NO
g. Oxygen
YES
NO
Explain your reasoning in distinguishing between the “yes” and “no” answers. Specifically, what do the energy sources have
in common that makes them different from the non-energy sources?
Correct, Scientific Answer: Humans obtain energy in the form of chemical bond energy in the food that they eat. Several
other molecules above (water& nutrients) are all incorporated into the body, but are not utilized as energy sources; their
bonds contain very little chemical potential energy and processes within the human body do not utilize these molecules
during energy transfer. Oxygen is important in releasing potential energy through the electron transport chain, but is not
itself the energy source. Carbon dioxide is in the air we breathe, but is not incorporated into any bodily functions. Exercise
does not provide energy for people, but actually facilitates the loss of energy as heat because of increased cellular
respiration that is occurring. Sunlight is the primary energy source for plants, but not for humans (exception: sunlight has a
minor role in providing energy for synthesis of important vitamins within humans).
Processes = Digestion/Biosynthesis, Principles = Energy, Scale, Scale = Organismal -> Atomic/Molecular
Purpose of Question: A student that is accurately tracing energy understands that energy is stored as chemical bond energy
(i.e.- CPE) within carbon rich molecules. Students need to realize this to answer the question at a high level. The important
part of the response is that the energy is in the form of chemical bond energy.
Coding Rubric
Code
Example Student Responses
4 - Scientific
-No,Yes,No,No,No,No,No
3 - Mixed
2 - Informal
-No,Yes,Yes,No,No,No,No: Food, because that is
how we start the process of cellular respiration
acquiring energy as ATP for our cells to carry
out work. We get nutrients from food to carry out
the same process.
-Yes,Yes,Yes,No,No,No,Yes: Exercise uses
energy, people don’t do photosynthesis, again
carbon dioxide isn’t useful for cellular
respiration.
-Yes,Yes,Yes,Yes,Yes,Yes,Yes: Something needs to
work our body
-Yes,No,Yes,Yes,No,No
-Yes,Yes,Yes,Yes,No,No,Yes: Water, food,
nutrients and oxygen are all things our body
needs to survive. Exersice in the long run can
provide you with more energy.
Description
-Student chooses Yes for food and No for all other
responses, and provides no explanation or an
explanation consistent with food providing energy in
the form of chemical bond energy.
-Student chooses Yes for food and No for all other
responses, but explains that food is converted to
energy (Incorrect matter to energy conversion)
-Student chooses Yes for food and Yes for at least one
other response, but not all responses.
-Student chooses Yes for every response
-Student chooses No for “Food”
-Student explains that people create their own energy
GRAPGLUC
3. You eat a grape high in glucose content. How could a glucose molecule from the grape provide energy to move
your little finger?
a. The glucose is digested into simpler molecules having more energy.
b. The glucose reacts to become ATP (Adenosine Triphosphate).
c. The glucose is turned into energy.
d. The energy of the glucose is transferred to other molecules such as ATP.
e. The energy of the glucose is transferred to CO2.and H2O.
Processes = Digestion/Biosynthesis, Principles = Energy, Scale, Scale = Organismal -> Atomic/Molecular
Purpose of Question: This question explores whether students understand how chemical potential energy is
stored and released through molecular transformations of carbon. Very few students answer this question
correctly, showing us as instructors that they do not understand the flow of energy at an atomic-molecular level.
Students who answer A are not properly applying the principle of conservation of energy because they believe
one molecule with a certain amount of energy can be broken into molecules that have MORE energy. Students
who answered B are not properly tracing matter - they do not know the correct chemical composition of glucose
and ATP or they think one atom can become another (e.g. carbon can become phosphorus). Students who answer
C think that matter can be converted to energy and do not understand conservation of matter. D is the correct
answer. Students who answer E are confused, but know the equation for respiration.
Coding Rubric
Code
Example Student Responses
4 - Scientific
D
3 - Mixed
B, C, E
2 - Informal
A
Description
-Students understand that chemical bond energy
is transferred from one molecule to another
-Students think that matter is turned into energy
(B,C)
-Students trace chemical bond energy to the
wrong molecules (E)
-Students assume that energy can be created
within the body
GIRLGROW
4. When a baby was five months old, she weighed 15 lb. After 7 years, the baby has grown into a big girl, weighing 50 lbs.
Do you think the baby girl will need any of the following things to grow and gain weight? Please circle Yes or No and
explain your choice.
Does the girl need it
If you circled yes, explain how the girl’s body uses it. What
Things
to grow?
happens to it inside the girl’s body?
Sunlight has a very small role, but is involved in supplying energy
Sunlight
necessary for the synthesis of some molecules within the body, such
Yes
No
as vitamin D.
Water is necessary for maintaining the correct environment within
Water
Yes
No
the girl’s body. Also, the hydrogen and oxygen molecules in water
can be incorporated into biomolecules necessary for growth.
Oxygen gas is a reactant in the process of cellular respiration,
Air
Yes
No
which is necessary for utilizing chemical bond energy.
Food supplies both matter and energy for the girl. The atoms in the
food are incorporated into biomolecules, and the carbon
Food
Yes
No
containing compounds contain high amounts of chemical potential
energy.
Processes = Digestion/Biosynthesis, Respiration, Principles = Matter, Scale, Scale = Organismal -> Atomic/Molecular
Purpose of Question: Most students understand the basic things that a girl needs in order to live and grow, but few of them
accurately trace matter and energy through the processes responsible for the girl’s growth. This question provides the
opportunity for students to provide as much detail as they can, but they can also answer in ways that lack detail and
mechanisms involving matter and energy. Informal reasoning includes statements about “enablers” needed for growth
without references to specific matter and energy entities. The explanation is very important for coding this question.
Coding Rubric
Code
Example Student Responses
4 - Scientific
-Yes,Yes,Yes,Yes: See answer to question above.
3 - Mixed
2 - Informal
- Yes,No,Yes,Yes: She uses the energy form the
sun. Uses cellular respiration (air). Uses it for
energy (food).
- No,No,No,Yes: This is an input into cellular
respiration once it is made into glucose.
-Yes,Yes,Yes,Yes: Indirectly, the girl needs sun to
grow things that she eats. Hydration helps fuel
processes in her body. Air keeps her alive as she
grows O2 is needed. Food fuels her body to give
her energy and sugars that do work.
-No,Yes,Yes,Yes: Sunlight is necessary for the
plants. She will die of dehydration without water.
She will die without air. (Food circled) to carry
out cellular work, to grow.
Description
-Student chooses Yes for Water, Air and Food, and
either Yes or No for Sunlight, and provides model
based explanations that describe mechanisms by
which the matter and energy are necessary for the girl
to grow.
-Student chooses any responses and attempts to trace
matter and energy involved in the girl’s growth, but
includes at least one incorrect mechanism, or vague
mechanisms.
-Student chooses any responses, but talks about the
responses as enablers that cause the girl to grow,
making no references to matter and energy.
CARBPATHSA
5. Once carbon enters a plant, it can …
a. exit the plant in a molecule of CO2. Circle True or False
Explain
Correct, Scientific Answer: Cellular respiration occurs in plants, which would result in the loss of carbon dioxide
to the atmosphere.
Processes = Respiration, Principles = Matter, Scale, Scale = Organismal -> Atomic/Molecular
Purpose of Question: This series of questions assesses whether students see multiple fates of carbon within a
plant and whether they can accurately trace the path of carbon. To successfully answer each question, students
must first understand that carbon is taken in by plants in the form of carbon dioxide and the carbon is incorporated
into biomolecules during photosynthesis. Sophisticated answers will include process-based explanations. Part A
requires students to realize that plants respire, and requires an atomic-molecular understanding of carbon
transformation during cellular respiration.
Coding Rubric
Code
3 - Mixed
Example Student Responses
- During night time when there is no
photosynthesis then plants don't emmit O2
they give out CO2
- False: CO2 is converted to sugars
- True: Plants can exhale CO2 during dry
periods
- False: O2 exits the plant through the ETC
and phosphorilation oxidation, not CO2
Description
-Student chooses True and provides an
explanation that indicates plant
respiration
-Student chooses True but provides no
explanation or an explanation that does
not indicate that they realize plant
respiration produces CO2.
-Student chooses False, citing that plants
emit O2 instead of CO2.
-Student just states that carbon enters the
plant, but does not exit the plant.
2 - Informal
-False (NO EXPLANATION)
-Student chooses False with an
explanation that clearly does not trace
matter.
4 - Scientific
CARBPATHSB
Once carbon enters a plant, it can …
b. become part of the plant’s cell walls, protein, and fat. Circle True or False
Explain
Correct, Scientific Answer: Glucose is utilized throughout the plant to synthesize various organic molecules,
including structural, functional and genetic molecules.
Processes = Digestion/Biosynthesis, Principles = Matter, Scale, Scale = Organismal -> Atomic/Molecular
Purpose of Question: Students need to trace the carbon molecule through the processes of photosynthesis and
biosynthesis within a plant. Students don’t need to know all of the details, but keeping track of the carbon atoms
is critical for a principled answer.
Coding Rubric
Code
4 - Scientific
3 - Mixed
2 - Informal
Example Student Responses
True: Once broken down into its substituent
carbon and oxygens, it can be incorporated
into fatty acids, amino acids and or cell
structures
-False: Carbon is broken down into pyruvate
and then travels through a process called
photosynthesis.
-False: No because it is used for energy not
to be put into fats and stuff
-True (No Explanation)
Description
-Student chooses True and explains
carbon can be incorporated into various
cell structures via biosynthesis
-False: It is not a nutrient
-False: These are parts of living building
blocks of cells as carbon is not living (F13).
-Student chooses False and provides an
explanation that does not trace carbon or
provides no explanation.
-Student chooses True but provides no
explanation or a vague explanation about
how carbon becomes part of the plant.
-Student chooses False and explains that
carbon is not a part of every tissue listed,
such as DNA.
- Student chooses False and explains that
carbon somehow leaves the plant.
CARBPATHSC
Once carbon enters a plant, it can …
c. be consumed by an insect and become part of the insect’s body. Circle True or False
Explain
Correct, Scientific Answer: All parts of a plant contain carbon. An insect obtains its carbon from eating organisms
in lower trophic levels, including plants. The carbon molecules that an insect consumes are digested and
transported through the body and incorporated into various molecules within the insect.
Processes = Digestion/Biosynthesis, Principles = Matter, Scale, Scale = Organismal -> Atomic/Molecular
Purpose of Question: Similar to above, students need to trace the carbon molecule through the processes of
photosynthesis and biosynthesis within a plant, and also through digestion and biosynthesis within an insect.
Students don’t need to know all of the details, but keeping track of the carbon atoms is critical for a principled
answer.
Coding Rubric
Code
4 - Scientific
3 - Mixed
2 - Informal
Example Student Responses
-True: The molecules taken in by the insect
can be used to build larger biomolecules that
will be incorporated into the insects body or
it can be broken down in respiration to
release energy.
- True: The insect then uses that plant
matter/carbon for energy
- True: Carbon is in the leaves
- True: The carbon ingested by the insect
becomes part of the insect b/c it has digested
the carbon.
- False: If the plant is destroyed, the carbon
it gives off into the atmosphere
-False: It would just be ingested not become
part of the body
Description
-Student chooses True and explains that plant
matter is digested, by the insect, but then
incorporated into insect tissues (details included)
-Student chooses True and explains that matter is
converted to energy, or used for energy without
referring to a destination for the matter.
-Student chooses True but provides no
explanation or a vague explanation, not
explaining a mechanism by which the carbon is
transferred between organisms.
-Student chooses False and explains that all of
the ingested carbon leaves the body.
-Student chooses False and provides no
explanation or explains that carbon is used up by
the insect - not tracing carbon.
CARBPATHSD
Once carbon enters a plant, it can …
d. be turned into energy for plant growth. Circle True or False
Explain
Correct, Scientific Answer: Matter and energy are coupled, but not interchangeable. The bonds between carbon
atoms in a plant contain chemical energy, but carbon atoms cannot be converted to energy.
Processes = Digestion/Biosynthesis, Respiration, Principles = Matter, Energy, Scale = Organismal ->
Atomic/Molecular
Purpose of Question: A common error among students is the failure to properly distinguish matter and energy.
Carbon is involved in the process of capturing sunlight energy during photosynthesis, but cannot be converted
into energy as suggested by the question. Many students will respond with a “True” answer followed by an
explanation that supports the idea that they aren’t distinguishing matter and energy.
Coding Rubric
Code
4 - Scientific
Example Student Responses
- False: Plants receive their energy from the
sun
3 - Mixed
- True: Co2 is necessary for photosynthesis
- False: Not turned into energy, but used in
the process creating it.
- False: CO2 converted during
photosynthesis
2 - Informal
-True: Carbon is used up to power
photosynthesis which creates energy
Description
-Student chooses False and correctly describes
that plants receive energy from the sun, or that
matter cannot be converted into energy
-Student chooses True and explains that matter
can be converted to energy
-Student chooses False and indicates that plants
create energy
-Student chooses False but provides no
explanation or a vague explanation that does not
explicitly show that they understand that matter is
not converted to energy
-Student chooses either True or False and
provides an explanation that clearly shows they
are not tracing matter or energy, but instead
indicates that matter is "used up"
CARBPATHSE
Once carbon enters a plant, it can …
e. exit the plant in a molecule of O2 during photosynthesis. Circle True or False
Explain
Correct, Scientific Answer: Carbon and oxygen are two different atoms, and carbon cannot be converted into
oxygen.
Processes = Photosynthesis, Principles = Matter, Scale, Scale = Organismal -> Atomic/Molecular
Purpose of Question: Students struggle to keep track of atoms and molecules through chemical processes. In this
scenario, it is impossible for an atom of carbon to be contained in a molecule of oxygen gas. Yet, many students
will answer ‘true” to this question. Students may believe that atoms can be converted to other types of atoms, but
more likely they are applying macroscopic scale ideas to atomic-molecular scale questions and are not
appropriately tracing matter (e.g. plants take in CO2 and give off O2).
Coding Rubric
Code
4 - Scientific
3 - Mixed
2 - Informal
Example Student Responses
- False: Carbon cannot become O2.
Although O2 does leave during
photosynthesis, it’s not a carbon molecule.
- False: Leaves as CO2
- True: CO2 -> O2 in plants
- True: That is a scientific fact.
Description
-Student chooses False and explains that O2 does
not contain carbon atoms.
-Student chooses False but provides inaccurate or
vague explanation.
-Student chooses True and explains that oxygen
is a product of photosynthesis. These responses
are usually consistent with the idea that students
see oversimplified gas-gas and solid-solid cycles.
-Student chooses True or False and shows no
commitment to tracing matter or energy.
BIOFUEL
6. Explain why the use of biofuels instead of fossil fuels is a proposed strategy to slow the rate of global climate
change. Use as much detail in your answer as you can.
Correct, Scientific Answer: Biofuels are made from plants that were recently grown. Both biofuels and fossil fuels
are converted to carbon dioxide when combusted, but the carbon that is contained in biofuels was recently
converted to organic carbon through photosynthesis, and would have been returned to the atmosphere via
decomposition of the plant material anyway. Thus, burning biofuels contributes no net increase in atmospheric
carbon dioxide levels, which are the primary cause of climate change. The carbon contained in fossil fuels has
been located in solid and liquid form in the Earth for millions of years, and would not be expected to be converted
to carbon dioxide by natural processes. Therefore, burning fossil fuels does result in a net increase in
atmospheric carbon dioxide levels.
Processes = Photosynthesis, Respiration/Combustion, Principles = Matter, Scale, Scale = Ecosystem ->
Atomic/Molecular
Purpose of Question: In order to explain why biofuels are considered to reduce the effects of climate change,
students need to understand that the carbon dioxide released during biofuel combustion was recently taken out of
the atmosphere via photosynthesis, whereas fossil fuels have been located in the ground for millions of years and
would not be released to the atmosphere without human intervention. Students A) think that biofuels result in less
carbon dioxide emissions than fossil fuels when burned, failing to trace carbon during combustion, B) say that
biofuels don’t give off greenhouse gases at all, (similar reasoning to A, but essentially seeing fossil fuels as
unnatural and biofuels as “natural”), C) Fail to recognize the age of organic carbon in biofuels and fossil fuels, D)
confuse the greenhouse effect with ozone layer depletion.
Coding Rubric
Code
Example Student Responses
4 - Scientific
Biofuels remove Co2 while growing along with
the CO2 they release when burning staying
mostly carbon neutral. Fossil fuels have no CO2
balance.
3 - Mixed
-Biofuels are more organic substances that when
combusted do not let off CO2 admissions.
- They do not emit greenhouse gases like fossils
fuels. They will not create a heat trapping smog.
That doesn’t allow heat to escape.
2 - Informal
-Fossil fuels burn up the ozone layer, increasing
climate change, biofuels are more environment
friendly option.
Description
-Student explains that carbon dioxide released from
biofuels during combustion is part of a short term
carbon cycle (plants remove CO2 from atmosphere
while growing, and most of this carbon would be
oxidized by decomposers soon after plant death.
-Student references greenhouse gases, CO2 or other
specific matter containing compounds in relation to
the combustion of biofuels, but cites incorrect facts,
such as the idea that biofuels do not emit, or emit less
CO2 or greenhouse gases when burned.
-Students understand oxidation of biofuels releases
CO2, but they do not reference the fact that plants
remove CO2 from the atmosphere while growing.
-Student does not reference specific matter containing
entities in relationship to the combustion of biofuels.
Often, students repeat common “environmental”
slogans they’ve heard, sometimes including the ozone
layer.