Energy Flow DQC’s
Unlike matter, which cycles within the Earth’s ecosystems, energy flows directionally, entering the
Earth’s ecosystems as sunlight and leaving as reflected sunlight or heat. The biosphere is an “open”
system with respect to energy. However, energy and matter are coupled, but are not interchangeable;
students struggle to understand this relationship. A common misconception is that matter is converted to
energy during transformations of organic material, and is often accentuated by commonly used phrases
(e.g. “Cereal at breakfast provides the energy needed for an active day”). Plants capture solar energy and
store it as chemical energy within carbon compounds, and most of this chemical energy is converted to
heat energy during cellular respiration. Two Diagnostic Question Clusters (DQC’s), Energy Pyramid
and Rainforest provide parallel questions to diagnose student reasoning about energy flow through
ecosystems. Both DQC’s ask students to reason about an ecosystem scale energy flow question, and
subsequent questions diagnose their ability to trace energy through individual processes involved in
energy flow through ecosystems. The goal is to identify the knowledge gaps, misconceptions and
misapplications that prevent students from understanding ecosystem scale questions. The names of
individual questions categorized by process are shown in the table below.
Processes
Multiple Process
Photosynthesis
Energy Pyramid
ENERPYR1 (1)
CORNGROW (7),
Transformation – Plant – Plant
Transformation Plant – Animal
GRAPGLUC (4)
Transformation – Plant to Decomposer
Transformation – Animal to Animal
Transformation – Energy Loss
Respiration – Decomposition
BREADMOLD (6)
TREEENER (3)
DEERWOLV (2)
TROPHERNER (5)
BREADMOLD (6),
TREEENER (3)
Rainforest
TROPFOREST (1)
ECOENER1 (2a),
OWLSUN (2b)
ENERGYL1 (3),
TREEFOREST (6)
TREEFOREST (6)
ENERGAINA (4a)
OWLSUN (2b)
BREADMOLD (5)
ENERGAINB (4b)
COMPOST (7),
BREADMOLD (5)
Rainforest Diagnostic Question Cluster
A large proportion of general biology students assume that both matter and energy are recycled within
ecosystems, indicating that students have more trouble tracing energy in ecosystems than matter. The
multiple process question at the beginning of this DQC asks students to decide whether matter and
energy are recycled within ecosystems, and provide a detailed explanation of their answer. Subsequent
questions 2-7 are designed to further diagnose student reasoning about energy flow within ecosystems,
and their ability to identify the relationship between matter and energy. Most questions are posed at the
scale of the ecosystem, requiring implicit knowledge of molecular processes. Questions three and six ask
questions directed more at the molecular scale.
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. Mixed reasoning presents itself in several different ways, thus level 3 answers
are divided up into subcategories to reflect different types of responses.
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.
Rainforest Diagnostic Question Cluster
Please answer the questions below as carefully and completely as you can.
1. A tropical rainforest is an example of an ecosystem. Which of the following statements about matter
and energy in a tropical rainforest is the most accurate? Please choose ONE answer that you think is
best.
A) Energy is constantly recycled, but matter is not recycled.
B) Matter is constantly recycled, but energy is not recycled.
C) Both matter and energy are constantly recycled.
D) Neither matter nor energy are recycled.
Please explain why you think that the answer you chose is better than the others.
Matter is neither created nor destroyed. Within an ecosystem, matter cycles through various biological,
chemical and geological forms. Much of the biosphere is made up of carbon atoms, which enter the
biosphere through photosynthesis, and leave it through combustion or respiration. Energy, however is
not recycled within an ecosystem. Nearly all energy on the planet originates from the sun, and leaves the
planet as heat lost to the atmosphere, which is never recaptured by plants, animals or nonliving objects.
Processes = Multiple Process, Principles = Tracing Matter and Energy Scale = Ecosystem ->
Atomic/Molecular
Purpose of Question: This question explores student understanding of conservation of matter and
energy. It requires students to know that ecosystems are “closed” with respect to matter, but “open”
with respect to energy. Students providing answers A or C do not correctly trace energy through
ecosystems, not realizing that energy flow is directional instead of cyclical. The opposite is true for
matter. Students answer with response A or D, which means that they assume that matter can be created
from substances outside of the Earth, possibly from energy.
Coding Rubric – Rainforest #1
Code
Example Student Responses
Description
4 - Scientific
"B, Trees grow, they die. When they die they
decompose they give off heat energy which
escapes through the atmosphere. Then another
plant or host uses the nutrients from the dead
tree with help of the sun starts to grow." (RF-20)
3a - Mixed
“C, Energy is always conserved it is never
destroyed. Matter cannot be destroyed in
chemical reactions because they must both be
conserved, they have to be recycled.” (RF-13)
3b - Mixed
Student chooses B. They either provide no
explanation or in their explanation, they correctly
invoke the laws of conservation of matter and energy.
They may say that energy enters as sunlight during
photosynthesis and exits as heat during
decomposition.
Student chooses C, and explicitly cites the laws of
conservation of energy and/or matter as their reason.
They can cite the law of thermodynamics, or use
words like "energy/matter cannot be created or
destroyed." This is an over application of the
conservation laws/ fails to recognize the limits of the
laws.
Student chooses any incorrect letter and cites that
matter can be converted to energy or vice versa.
“C, The plants in the rainforest are able to
convert heat into energy that they can use, and
the animals eat plants and other animals using
their matter to create the energy they need.”
(RF-24)
“C, life converts one to the other through
cellular processes, ATP synth and
photosynthesis”(RF-1)
“C, I believe that both energy and matter are
Student chooses C and gives a vague explanation
recycled because in an ecoystem one species
about matter and energy being able to be used over
trash or waste acts a food for another species.
and over, but doesn't explicitly invoke laws of
This continues in a cycle so that is why I feel
conservation OR student chooses A and thinks that
energy and matter are recycled.”(RF-25)
either matter can’t be recycled OR student chooses A
“A, energy is passed through organism to
or C and doesn’t provide and explanation.
organism in a food chain. Starting at the bottom
I think that energy is being used and reused as it
moves up the food chain until it reaches the top.
I don’t think matter is recycled because if
something is eaten or dies their matter isn’t
recycled back into another form unless its
(love?) by decomposers” (RF-46)
“C, this answer is best because every living
Student chooses any letter and doesn’t trace energy
organism requires energy to live and they also
or matter. They may use “school science” words
depend on other organisms to gain that energy
indicative of procedural display, chose D and provide
via food.” (R53)
no explanation, or give a “vitalistic” explanation.
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
3c - Mixed
2 - Informal
1a
1b
1c
1d
1e
2a. Which of the following are energy sources for plants? Please circle ALL correct answers.
A) nutrients
B) sunlight
C) water
D) carbon dioxide
E) others: List sources:
Processes = Photosynthesis, Principles = Tracing Energy, Scale = Ecosystem -> Atomic/Molecular
Purpose of Question: This question requires students to understand that ecosystems are “open” with
respect to energy and that sunlight provides the ultimate source of energy for food webs. Few students
will answer part A incorrectly, as they know that sunlight is the primary energy source for the Earth’s
ecosystems. However, part B tests them to apply this principle by tracing energy from the sun all the
way to a carnivore (owl). Students who answer part B incorrectly may know the textbook answer for
where energy comes from, but don’t apply it when thinking about ecosystems.
Coding Rubric – Rainforest #2a
Code
Example Student Responses
4 - Scientific
B
3a - Mixed
AB, BC, BD, BE
3b - Mixed
ABC, ABD, ABE, BCD, BCE
3c - Mixed
ABCDE, BCDE, BADE, BACE, ABCD
2 - Informal
any combo that doesn't have B in it
1a
1b
1c
1d
1e
Description
Student correctly chooses B (sunlight) as source of
energy and does not choose any other answers
Student correctly chooses B (sunlight) and incorrectly
chooses one of the other letters.
Student correctly chooses B (sunlight) and incorrectly
chooses two of the other letters.
Student correctly chooses B (sunlight) and incorrectly
chooses three or more of the other letters.
Student doesn’t choose sunlight as one of the choices
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
2b. Owls are nocturnal, meaning that they search for food at night. If all sunlight was blocked from the
ecosystem in which owls live, could the owls still survive? Circle Yes or No.
Why or why not?
Even though owls are nocturnal, they still need the sun in order to live. Energy is not recycled within
ecosystems, thus a constant supply of energy is required from the sun in order that both plants and
higher trophic levels can survive. Wolves rely on photosynthesis by plants and the transfer of energy
between plants and herbivores.
Processes = Photosynthesis, Transformation, Principles = Tracing Energy, Scale = Ecosystem ->
Atomic/Molecular
Purpose of Question: This question requires students to understand that ecosystems are “open” with
respect to energy and that sunlight provides the ultimate source of energy for food webs. Few students
will answer part A incorrectly, as they know that sunlight is the primary energy source for the Earth’s
ecosystems. However, part B tests them to apply this principle by tracing energy from the sun all the
way to a carnivore (owl). Students who answer part B incorrectly may know the textbook answer for
where energy comes from, but don’t apply it when thinking about ecosystems.
Coding Rubric – Rainforest #2b
Code
4 - Scientific
3a - Mixed
3b - Mixed
Example Student Responses
Description
“No, all animals need the sun to live in one way
or another. If there was no sun, the food that
owls eat would not survive because plants are
the only way to change the inorganic materials
we need to live into organics that we can then
use.” (RF-4)
“No, their prey needs sunlight, so they could
not survive if their prey can’t survive without
sunlight” (RF-7)
Student gives correct answer (No) and they correctly
trace energy from the sun to primary producers
through a primary consumer to the owl, i.e. Includes
the idea that the sun provides energy for plant growth
and that the energy is transferred to the owl through
trophic connections.
Student gives correct answer (No), but their answer
doesn't incude all important trophic connections, i.e.
misses the connection to primary producers AND/OR
misses connections through secondary consumers.
“ No, the organisms they eat most likely need
sunlight to survive. Without sunlight the owls
couldn’t eat.” (RF-21)
“No, the sunlight gives them certain
vitamins/nutrients they wouldn’t get out of
food.” (RF-5)
“No, all living things need sunlight. Owls
breath oxygen and plants make oxygen and need
sunlight to do it.” [student is tracing oxygen
rather than energy in carbon-based molecules]
(RF-26)
3c - Mixed
2 - Informal
1a
1b
1c
1d
1e
“No because they need the sunlight hours to
have time to rest without fear of being attacked
by their predators.” (RF-52)
“No, even though they sleep during sunlight,
they intake energy from the sun” (RF-18).
The question is very broad. The ecosystem
would be entirely different without sunlight and
therefore owls would probably not have a source
of food. If they still had food, then I would say
yes, they can survive. (RF-16).
“Yes, they could survive without sunlight
because they could adapt to the new condition.
They are already capable of hunting at night so
they would still have nutrients.”
Student gives correct answer NO, but their
explanation does not include tracing of energy
through trophic connections. Instead, they indicate
another plausible, biological reason like inability to
synthesize vitamin D without sunlight or an inability
to adapt behaviorally or socially. OR
Student chooses "No" and does not provide an
explanation.
Student gives correct answer NO, but their answer is
vitalistic. Says owls "need" sunlight, but not why
they need it. OR Student does not provide a "Yes/No"
answer, but does provide an explanation.
Student answers YES, and their answer does not
include tracing of energy through trophic
connections.
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
3. Sunlight helps plants to grow. Where does light energy go when it is used by plants? Please decide
whether you think each statement is true or false.
T F Some light energy is turned into glucose of the plants.
T F Some light energy is turned into ATP (adenosine triphosphate) in the plants.
T F Some light energy is used up to power cellular processes and disappears..
T F Some light energy becomes chemical bond energy.
Processes = Photosynthesis, Principles = Tracing Energy, Scale = Organismal -> Atomic/Molecular
Purpose of Question: This question explores students’ understanding of the role of photosynthesis in
converting light energy into chemical bond energy. Students may not understand that principle of
conservation of energy and think that energy can be “used up” or that it can be converted into matter
(e.g. glucose).
Coding Rubric – Rainforest #3
Code
Example Student Responses
4 - Scientific
F, F, F, T
3a - Mixed
T, F, F, T ,
F, T, F, T
T, T, F, T
3b - Mixed
F, F, T, T
3c - Mixed
F, T, T, T
T, T, T, T
T, F, T, T
2 - Informal
X, X, X, F
1a
1b
1c
1d
1e
Description
Student chooses true for choice D and not others.
Student doesn’t think energy can be converted to
matter (choices A and B). Student is deterred by the
sloppy terminology of “used up” (C). Student sees
conservation of energy in the form of transformation
of light to chemical energy (D).
Student chooses true for choice D, but also chooses
true for A and/or B indicating they think energy can
be converted to matter. Student does not choose
choice C
Student chooses true for choice D, but also chooses
true for C indicating an attraction to colloquial terms
about energy. Student does not choose true for
choices A or B.
Student chooses true for choice D, but also chooses
true for choices A and/or B and choice C indicating
that they think energy can be converted to matter and
an attraction to colloquial terms about energy.
Student chooses false for choice D
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
4a. Of the energy gained by a plants (producers), about what percent is transferred to herbivores like
rabbits?
A) 90-100%
B) 60-70%
C) 30-40%
D) 10-20%
4b If you chose B, C or D, where does the energy go that does not get transferred between the plant and
rabbit?
The energy that is not transferred is lost as chemical bond energy in the feces of the rabbit, or is lost as
heat during the process of cellular respiration.
Processes = Transformation, Respiration, Principles = Tracing Energy, Scale = Ecosystem ->
Atomic/Molecular
Purpose of Question: This question explores whether students can trace energy through a food chain.
Students who choose answers A or B do not understand the principles associated with the transfer of
energy between organisms. More commonly, students do not know where the energy goes that is lost,
commonly citing that it is “used up” or “gone.”
Coding Rubric – Rainforest #4
Code
Example Student Responses
4 - Scientific
“D, it’s given off as heat, waste, and probably
something else that I can’t remember.” RF47
3a - Mixed
“C, it is dispersed into the environment” RF30
“C, The energy that is not transferred to the
rabbit is lost by the rabbits digestion of the plant
and may be released as heat energy from the
rabbit” RF24
3b - Mixed
“C, Excreted as waste.” RF13
“C, It stays with the plant if it is not fully eaten
or it is in the ground.” RF26
3c - Mixed
“D, used in plant process or wasted because
energy transfer is not efficient, i.e. plants used
more energy to make glucose than they get from
it.” RF1
2 - Informal
“D, it is lost” - RF22
“D, it dies off” – RF27
“B, not all of it can be digested and absorbed
by the rabbit” – RF3
1a
1b
1c
1d
1e
Description
Student chooses D and correctly traces energy when
it is decoupled from matter during the process of
oxidation. Students may say that some energy is
released as heat or released to the atmosphere.
Student chooses an incorrect %, but in their
explanation, they still correctly trace energy when it
is decoupled from matter during the process of
oxidation. Students may say that some energy is
released as heat or released to the atmosphere.
Students are having trouble with the magnitude, but
not the concept. OR
Student chooses "D" and provides no explanation.
Student chooses any %, but does not correctly trace
energy when it is decoupled from matter during
oxidation. They may say that energy goes
somewhere (e.g. feces, stays in the plant, is in the
rabbits body), but DO NOT include energy emitted as
heat during oxidation. However, they DO NOT use
phrases like “used up” or “goes away” nor do they
give an indication that they think energy can
disappear. OR
Student chooses C and provides no explanation.
Student chooses any %, but does not correctly trace
energy. The student cites that the energy is used to
power other processes like photosynthesis or
transformation, but they do not say where the energy
went (i.e. name a location).
Student chooses A or B and provides no explanation,
OR
student chooses any % and doesn’t explain where
energy went OR name any processes in which the
energy might have been used.
A
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
5. A loaf of bread was left uncovered for two weeks on a balance measuring its mass. Three different
kinds of mold grew on it. Assuming that the bread did not dry out, which of the following is a
reasonable prediction of the weight of the bread and mold together?
A) The mass has increased, because the mold has grown.
B) The mass remains the same as the mold converts bread into biomass.
C) The mass decreases as the growing mold converts bread into energy.
D) The mass decreases as the mold converts bread into biomass and gases.
Please explain your answer and indicate any important transformations.
Correct, Scientific Answer: When mold grows on the bread, it is actually decomposing the bread and
breaking down organic molecules. Some of the carbon in these organic molecules is converted to carbon
dioxide during cellular respiration and some is incorporated into the biomass of the mold. The mold is a
heterotrophic organism and cannot photosynthesize, thus (a) is incorrect. Choice (b) assumes that the
mold is not respiring, and subsequently losing mass, which is incorrect. Choice (c) is incorrect because
matter cannot be converted to energy.
Processes = Respiration, Biosynthesis Principles = Matter, Scale, Scale = Organismal ->
Atomic/Molecular
Purpose of Question: Most students recognize that mass is transferred from the bread to the growing
mold. Very few students, however, account for the carbon cost (loss to atmosphere during metabolism)
during the process of assimilating bread carbon into biomolecules within the mold. Students more
readily use an overly simplified solid-solid cycle rather than incorporate solid-gas matter conversions.
Several students improperly cited “conservation of mass” as a reason why the mold + bread combo
would not lose mass.
Coding Rubric – Rainforest #5
Code
Example Student Responses
Description
4 - Scientific
D: The mold will grow, buit also gives off waste
gasses like CO2 and water vapor, which will
decrease the mass of the bread and mold (GJ8)
Student chooses D, and describes how some bread
biomass is incorporated into the mold, but some is lost
as CO2 to the atmosphere, likely due to cellular
respiration.
3a - Mixed
C: The molds were using the bread as a source of
energy therefore the nutrients from the bread
were being lost. (GJ9).
Student chooses C and says that some of the mass is
being converted to energy or student chooses D and
confounds matter and energy in their explanation.
D: The mold takes resources from the bread and
converts it into energy for itself to grow and
expand, what it cannot use will turn into waste
and gas (GJ46)
3b - Mixed
D: The mold uses the bread to grow by
consuming it. The mold doesn't use all it
consumes so the waste is expelled (GJ55).
Student chooses letter D, but provides a vague
explanation that does not explicitly explain that gases
are a product of respiration by the mold, often talking
about waste from mold.
3c - Mixed
B: The mold uses bread and water to grow by
decaying it however molds mass increases
(GJ53).
Student chooses B and provides no explanation or
recognizes transformation but not oxidation. They
may cite conservation of matter in their answer OR
student chooses A and thinks that the bread is not the
only source of mass for the mold.
A: not very sure but, I would assume the bread is
not the only source of food for the mold.
Therefore the biomass would still increase even
though some of the bread is gone.” (RF-16)
2 - Informal
1a
1b
1c
1d
1e
A: It’s a growing fungus (GJ48).
Student chooses letter A and provides no explanation
or chooses A or B, but their explanation does not show
a commitment to tracing matter or energy.
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
6. The trees in the rain forest contain molecules of chlorophyll a (C55H72O5N4Mg). Decide whether each
of the following statements is true about the atoms in those molecules. Circle True (T) or False (F).
Some of the atoms in the chlorophyll came from …
T F carbon dioxide in the air.
T F sunlight that provided energy for photosynthesis.
T F water in the soil.
T F nutrients in the soil.
T F glucose produced by photosynthesis
T F the seed that the tree grew from.
Processes = Photosynthesis, Transformation, Principles = Tracing Matter, Scale = Atomic-Molecular
Purpose of Question: This question asks students to accurately trace molecules of chlorophyll back to
their entry into the plant. Some students think that energy can become matter and vice versa (2nd
Response). Some students do not believe that plants get CO2 for photosynthesis from the air. Hydrogen
atoms in the water are incorporated into glucose during photosynthesis, and the glucose is utilized in the
synthesis of other molecules, such as chlorophyll. The seed and the soil also provide minerals such as
nitrogen that are in the chlorophyll. Most importantly, students must be able to trace particular atoms
from their source to their sink within the chlorophyll molecule, which is difficult at an atomic-molecular
scale.
Coding Rubric – Rainforest #6
Code
Example Student Responses
4 - Scientific
T, F, T, T, T, T
3a - Mixed
X, F, X, X, X, X but not T, F, T, T, T
3b - Mixed
NA
3c - Mixed
X, T, X, X, X, X
2 - Informal
1a
1b
1c
1d
1e
Description
Student thinks molecules could come from any of the
material sources listed, but does not think that atoms
can come from sunlight.
Student thinks molecules could come from some of
the material sources listed, but does not think that
atoms can come from sunlight.
NA
Student thinks molecules could come from all or some
of the material sources listed, but also thinks atoms
can come from sunlight.
F, F, F, F, F, F
Student things that none of the sources listed could
have contributed to the molecules in chlorophyll.
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
7. When the leaves in a compost pile decay, what do you think happens to the
mass of the leaves? Circle True (T) or False (F).
T F The mass disappears when the leaves decompose.
T F The mass is turned into to heat energy.
T F The mass is converted into soil minerals.
T F The mass is converted into carbon dioxide and water.
Please explain your answers.
The matter in the dead leaves is decomposed by organisms in the compost pile. The carbon and
hydrogen in the organic substances (along with oxygen from the air) is converted to carbon dioxide and
water. The minerals in the leaves are not respired, but are liberated from the organic compounds and
remain in the soil.
Processes = Respiration, Principles = Tracing Matter, Scale = Organismal
Purpose of Question: This question asks student to properly trace matter through the process of
decomposition. Many students do not realize that decomposition involves respiring microbes that take
in carbon compounds from dead organisms and release CO2 and water primarily. Some atoms are also
mineralized during decomposition and released into the soil in a non-gaseous form, such as phosphorus.
Coding Rubric – Rainforest #7
Code
4 - Scientific
3a - Mixed
Example Student Responses
“F,F, T, T – The leaves are decomposed into very
important minerals in soil and also during
decomposition the leaves matter is turned into
CO2 and water.” (RF-36)
“F, T, T, T - The mass of the leaves is then
converted to energy of other matter.” RF-17
“T, F, T, T - The mass goes away because it is
converted into either nutrients such as soil
minerals, CO2, and H2O.” RF10
3b - Mixed
“T, T, T, T bacteria breakdown the organic
matter for energy, releasing CO2 and H20,
leaving behind useable mineral as soil.” (RF-1)
“F, F, T, F – “The mass stays the same the
leaves just break into tiny particles.” – RF35
“F, T, T, F – decomposers break down dead
organic matter and the mass is converted to
energy and nutrients.” – RF46
Description
Student correctly thinks that mass is converted into
carbon dioxide, water, and soil minerals (F, F, T, T)
and does NOT think that mass can be converted to
energy or that mass “goes away”.
Student correctly thinks that mass is converted into
carbon dioxide, water, and soil minerals, but also
thinks that mass can be converted into energy and/or
that mass “goes away”.
Student thinks mass cannot be converted to carbon
dioxide and water, but they do think it can be
converted to soil minerals indicating a difficulty with
solid-gas transformations or solid-liquid
transformations.
“T,T,T,F Heat is given off through
decomposition, the mass becomes nutrients in the
ground, I don’t think water is a byproduct of
decomposition.” – RF7
3c - Mixed
“T,F,T,F The nutrients in the leaves transfer to
the soil.” – RF28
“F, T, F, F – The leave isn’t there anymore but
its mass would have to convert to something
else.” – RF8
Student thinks mass can’t be converted to soil
minerals, but they think that some matter can be
converted to energy, some mass just goes away,
and/or some mass is converted to carbon dioxide.
“T, T, F, F. The mass went away because it
turned into energy.”
2 - Informal
1a
1b
1c
1d
1e
“F, T, F, T. Mass can’t just disappear and I
don’t think it could be created into soil
materials.” – RF19
T, F, F, F
Students exhibit no commitment to tracing energy and
only say that mass can “go away”
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