1. The electron transport chain is a part of cellular respiration. The diagram below shows the

movement of ions in the electron transport chain within a mitochondrion.

 

 

Which statement best describes the movement of ions shown in the diagram?

(A) The electron transport chain is used to move hydrogen ions to the inner membrane space,

where they create a highly reducing environment and hydrolyze CO2 to produce sugar.

Distractor Rationale:

This answer suggests the student may understand that hydrogen ions are being transferred

to the inner membrane space, but does not understand that carbon dioxide is not

hydrolyzed in this location or that an electrochemical gradient is generated to move

hydrogen ions through ATP synthase and power the production of ATP through

chemiosmosis.

(B) Hydrogen ions diffuse into the inner membrane space and are pumped against an

electrochemical gradient through the electron transport chain, which provides the energy

needed to generate ATP through chemiosmosis.

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Distractor Rationale:

This answer suggests the student may understand that hydrogen ions move into the inner

membrane space, but does not understand that the hydrogen ions are pumped into the

inner membrane space via the electron transport chain to produce an electrochemical

gradient, and that the ions then flow through ATP synthase to the mitochondrial matrix to

power the production of ATP.

(C) The proteins in the electron transport chain create an electrochemical gradient by pumping

hydrogen ions to an area of high concentration, which powers ATP production when the

hydrogen ions diffuse back into the mitochondrial matrix.

Rationale:

This answer suggests the student understands that hydrogen ions are pumped into the

inner membrane space via the electron transport chain to an area of high concentration,

which produces an electrochemical gradient that is used to produce ATP.

(D) Hydrogen ions are reduced as they move through the electron transport chain in order to

transfer electrons to ADP and phosphate to make ATP in the inner membrane space.

Distractor Rationale:

This answer suggests the student may understand that hydrogen ions move through the

electron transport chain, but does not understand that hydrogen ions are not reduced as

they are pumped into the inner membrane space and that these ions provide the energy for

ATP synthesis due to the generation of an electrochemical gradient. 

Aligned to: LO 2.5 CA 2.5: Explain Energy Use, Storage & Capture

2. A certain drug greatly disrupts cellular respiration. When the drug is introduced into the body, the

following observations are made:

Acetyl CoA builds up in the mitochondrial matrix;•

There is a decrease in the amount of CO2 diffusing out of the mitochondria; and•

Low levels of NADH and FADH2 slow oxidative phosphorylation on the inner mitochondrial

membrane.

•

 

Which statement best explains how this drug disrupts cellular respiration?

(A) The drug prevents the movement of hydrogen ions into the inner membrane space, which

prevents the formation of an electrochemical gradient.

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Distractor Rationale:

This answer suggests the student may understand that the movement of hydrogen ions into

the inner membrane space is necessary to establish an electrochemical gradient, but does

not understand that the reduction of NAD+ and FAD and the production of carbon dioxide

are processes in the citric acid (Krebs) cycle, which occur in the mitochondrial matrix.

(B) The drug prevents enzymes from splitting glucose into pyruvic acid during glycolysis and

prevents the production of ATP during substrate-level phosphorylation.

Distractor Rationale:

This answer suggests the student may understand that enzymes split glucose into pyruvic

acid during glycolysis and that ATP is produced during substrate-level phosphorylation, but

does not understand that carbon dioxide is not released during glycolysis and that the

reduction of NAD+ and FAD and the production of carbon dioxide are processes involved in

the citric acid (Krebs) cycle.

(C) The drug prevents the reduction of NAD+ and FAD by binding to the enzymes involved in

the citric acid (Krebs) cycle.

Rationale:

This answer suggests the student understands that the observations made are all directly

related to the processes involved in the citric acid (Krebs) cycle, which involves transforming

pyruvate into acetyl CoA, reducing NAD+ to NADH, and producing CO2.

(D) The drug prevents the oxidation of NADH and FADH2 by blocking proteins from donating or

accepting electrons in the electron transport chain.

Distractor Rationale:

This answer suggests the student may understand the relationship among NADH, FADH2,

and the electron transport chain, but does not understand that the observations show that

the reduction of NAD+ and FAD and the production of carbon dioxide are processes

involved in the citric acid (Krebs) cycle.

Aligned to: LO 2.5 CA 2.5: Explain Energy Use, Storage & Capture

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3. The diagram below shows the processes occurring in and around the inner mitochondrial

membrane.

 

 

Based on the diagram, which question best investigates a factor that affects the processes?

(A) If water is generated in the mitochondrial matrix, will the mitochondrial matrix become

hypotonic to the intermembrane space as the processes occur?

Distractor Rationale:

This answer suggests the student may understand that a high concentration of water on one

side of a plasma membrane will make that area hypotonic to another side with a lower water

concentration, but does not understand that water can diffuse through plasma membranes

(via aquaporins) so a hypotonic environment will not be produced.

(B) If oxygen gas is being converted into water in the mitochondrial matrix, will the volume of the

mitochondrial matrix change as the processes occur?

Distractor Rationale:

This answer suggests the student may understand that oxygen gas is converted into a liquid

in the matrix and changing a gas into a liquid decreases its volume, but does not

understand that water and oxygen can diffuse directly through plasma membranes, so

there will be no change in the volume of the mitochondrial matrix.

(C) What effect will lowering the pH in the intermembrane space have on the proteins in the

inner mitochondrial membrane?

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Rationale:

This answer suggests the student understands that H+ ions are being pumped into the

intermembrane space, which lowers the pH, and that lowering the pH in this space even

further may affect the structure and function (denaturing) of proteins in the membrane and

prevent the proteins from pumping H+ ions or transferring electrons in the electron transport

chain.

(D) What effect will the movement of negatively charged ions through the inner mitochondrial

membrane have on the production of water?

Distractor Rationale:

This answer suggests the student may understand that the movement of electrons through

the electron transport chain results in water molecules, but does not understand that the

electrons are being passed from protein to protein through reduction-oxidation reactions

within the membrane, and the electrons are not being passed within the membrane itself.

Aligned to: LO 2.5 CA 2.5: Explain Energy Use, Storage & Capture

4. A root cutting is placed in a sealed container. The concentrations of carbon dioxide and oxygen

gas in the container are measured and recorded in millimeters of mercury (mmHg) every 6 hours

over the next 24 hours. The results are shown in the table below.

 

 

Which statement best explains the results of the experiment?

(A) The root cutting is undergoing anaerobic fermentation because the root cutting is running

out of oxygen and it is not able to undergo the citric acid cycle or oxidative phosphorylation.

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Distractor Rationale:

This answer suggests the student may understand that an organism undergoes fermentation

when oxygen levels are too low, but does not understand that oxygen is not used during

fermentation and that the root cutting is undergoing cellular respiration, as evidenced by the

oxygen concentration decreasing and the carbon dioxide concentration increasing.

(B) The root cutting is using the Calvin cycle to generate energy and is consuming oxygen

because there is not enough light available to carry out light reactions.

Distractor Rationale:

This answer suggests the student may understand that the root cutting is consuming

oxygen, but does not understand that carbon dioxide (not oxygen) is used during the

Calvin cycle to produce sugar and that the plant is undergoing cellular respiration, as

evidenced by the oxygen concentration decreasing and the carbon dioxide concentration

increasing.

(C) The root cutting is undergoing aerobic cellular respiration because the root cutting is

generating carbon dioxide from organic molecules and is reducing oxygen to form water.

Rationale:

This answer suggests the student understands that the root cutting is undergoing cellular

respiration because the oxygen concentration is decreasing (oxygen is reduced to form

water in cellular respiration) and the carbon dioxide concentration is increasing (carbon

dioxide is generated from organic molecules during the citric acid [Krebs] cycle).

(D) The root cutting is undergoing photolysis in the light-dependent reactions because oxygen is

being split and combined with carbon to form carbon dioxide.

Distractor Rationale:

This answer suggests the student may understand that photolysis occurs during the light-

dependent reactions in photosynthesis, but does not understand that oxygen is not split

and combined with carbon to form carbon dioxide during photosynthesis, and that the plant

is undergoing cellular respiration, as evidenced by the oxygen concentration decreasing and

the carbon dioxide concentration increasing.

Aligned to: LO 2.5 CA 2.5: Explain Energy Use, Storage & Capture

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5. The diagram below shows how the nutrients triglycerides, glucose, and amino acids are

metabolized to produce ATP in a mitochondrion.

 

 

 

Which scientific question is most appropriate to investigate the process of ATP production that is

shown in the diagram?

(A) How does the amount of ATP generation vary among each of the nutrients when oxygen

supplies are limited?

Rationale:

This answer suggests the student understands that cellular respiration of triglycerides and

amino acids requires oxygen to generate ATP and that only glucose can continue to be

catabolized when oxygen supply is limited, which may result in more ATP generated from

glucose when blood oxygen levels are low.

(B) How is the production of fatty acids in the cytosol affected by an excess supply of each

nutrient?

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Distractor Rationale:

This answer suggests the student may understand that excess nutrients are converted into

fatty acids in the cytosol and stored as body fat, but does not understand that this question

does not address the process of ATP production and therefore does not gather evidence

about the production of ATP.

(C) How does the Krebs cycle vary based on the nutrient being metabolized?

Distractor Rationale:

This answer suggests the student may understand that the nutrients are metabolized by

processes in the Krebs cycle, but does not understand that these processes in the Krebs

cycle do not change based on the nutrient used.

(D) How does NAD+ and FAD oxidation vary for each of the nutrients?

Distractor Rationale:

This answer suggests the student may understand the roles of NAD+ and FAD in cellular

respiration, but does not understand that the function of these molecules is the same

regardless of the type of nutrient being oxidized.

Aligned to: LO 2.5 CA 2.5: Explain Energy Use, Storage & Capture

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