Name Answer Key
Date
Period
3.7 Cell Respiration
1. Define cell respiration.
Cell respiration is the controlled release of energy from organic molecules in cells to form ATP.
2. State the equation for the process of cell respiration.
C6H12O6 + 6O2  6CO2 + 6 H2O + Energy
3. Distinguish between aerobic and anaerobic in terms of cell respiration. Outline the general
process of both.
Aerobic pathways require oxygen, and use glycolysis, the link reaction, Krebs cycle, and oxidative
phosphorylation to produces a large amount of ATP (36).
Anaerobic pathways do not require oxygen, produce lactic acid/lactate through lactic acid fermentation,
produces ethanol through alcoholic fermentation, occurs only in the cytoplasm of the cell, and produces
a small amount of ATP (2)
Process
Aerobic respiration breaks glucose down into pyruvate during glycolysis, pyruvate is converted into the
acetyl coA in the link reaction, which then joins with oxaloacetate to form citrate in the krebs cycle. Here
it is oxidized and decarboxylated forming NADH and FADH2, as well as ATP. NADH and FADH2 transfer
electrons to the Electron Transport Chain, where chemiosmosis and oxidative phosphorylation occurs.
Anaerobic respiration occurs in the cytoplasm, where glucose is broken down into pyruvate. In order to
continue to produce energy, NADH needs to be recycle into NAD+, where pyruvate is reduced and forms
lactate in lactic acid fermentation, or it is decarboxlyated and reduced to form ethanol in alcoholic
fermentation. (haven’t learned this yet)
4. Complete the table below summarizing the events of aerobic cell respiration.
Reaction
Location
Purpose
ATP yield
Glycolysis
Cytoplasm
Split glucose into pyruvate
and produce NADH and ATP
2
Link Reaction
Matrix of the
mitochondrion
Convert pyruvate (3C)
to acetyl CoA (2C)
0
Krebs Cycle
Matrix of mitochondrion
Form NADH, FADH2, and
ATP
2
Electron Transport
Chain/Chemiosmosis
Inner mitochondrial
membrane
Oxidative
phosphorylation
Inner mitochondrial
Membrane
Generate concentration
gradient using movement of
electrons to power ATP
synthase
Movement of H+ ions through
ATP synthase to form ATP,
using energy from movement
of electrons
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com
32-34
32-34
Name Answer Key
Date
Period
8.1/C3 Cell Respiration (AHL/Option content)
5. Many reactions in living things can be classified as either oxidation or reduction reactions.
These are particularly important in cell respiration and photosynthesis.
Complete the table below to compare oxidation and reduction reactions.
OXIDATION
REDUCTION
Electrons are…
lost
Gained
Oxygen is…
Gained
Lost
Hydrogen is…
Lost
Gained
6.
Define phosphorylation.
Addition of a phosphate group to a molecule. Substrate level phosphorylation occurs when an enzyme
transfers an electron directly from a substrate to a molecule of ADP. Oxidative phosphorylation occurs
using the movement of electrons to generate energy used to add a phosphate to a molecule of ADP.
Makes molecules less stable
7.
In the space below, draw a diagram to show the process of glycolysis.
Process of breaking glucose down into pyruvate, using two molecules of ATP to start the process. This
forms 2 pyruvate molecules, as well as 2 molecules of NADH, and a net gain of 2 ATP molecules.
8.
Explain the link reaction, including oxidative decarboxylation and conversion of pyruvate to
acetyl CoA and CO2.
In the link reaction, both pyruvate molecules are decarboxylated (lose a carbon which forms CO2),
oxidized (lose electrons), and combined with a molecule of coenzyme A to form 2 NADH and 2 acetyl
CoA.
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com
Name Answer Key
Date
9.
Period
Complete the table below with the functions of the structures of the mitochondrion.
How is each structure adapted to help maximize efficiency of respiration?
Structure:
Function:
Outer membrane
Separates internal and external components of
mitochondrion and controls entry/exit of materials
Location of Electron Transport Chain and ATP synthase,
pumps electrons and generates H+ gradient to produce ATP
and water.
Inner membrane
(including christae)
Matrix
Contains enzymes for link reaction and Krebs cycle to
produce acetyl CoA, NADH, and FADH2, and ATP
Inter-membrane space
Area where hydrogen ions accumulate to generate
concentration gradient and proton motive force.
10. List two electron carriers that are used in cell respiration.
 NADH
 FADH2
11. Outline the process of the Krebs Cycle.
Acetyl CoA will combine with a molecule of oxaloacetate to form Citrate. Citrate will be decarboxylated
(loses carbon, forms CO2) and go through a series of redox reactions (transfer of electrons) to
regenerate oxaloacetate. Decarboxylation will produce 2 CO2 and the redox reactions will produce 3
NADH and 1 FADH2 by transferring electrons from citrate to the electron carriers. ATP will also be
produced by substrate-level phosphorylation. For each molecule of glucose that is broken down, the
Krebs cycle will turn twice, producing 6 molecules of NADH, 2 molecules of FADH2, 4 molecules of CO2,
and 2 molecules of ATP.
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com
Name Answer Key
Date
Period
12. Annotate the diagram below with the stages of the electron transport chain and oxidative
phosphorylation. Include generation of a H+ concentration gradient in the inter-membrane
space, movement of electrons, oxidative phosphorylation by ATP synthase, use of O2 as the
terminal electron acceptor
H+
H+
H+
eNADH
H+
H+
H+
NAD+
e-
H+
H+
H+
FADH2
H
+
H+
FAD+
NADH and FADH2 will donate electrons to electron acceptors
in the ETC. The electrons will pass down the chain to the final
electron acceptor, oxygen, which will then combine with two
hydrogens to form water. As the electrons move down the
ETC, the proteins will pump hydrogen ions from the matrix to
the intermembrane space, generating a concentration
gradient, which generates a proton motive force (potential
energy). The hydrogen ions will move through the ATP
synthase, which will uses the energy from the ions to add a
phosphate molecule to ADP, forming ATP.
H+
O
+ H+
H2O
ADP
+P
ATP
13. In the space below, define the terms electron transport chain, chemiosmosis, and oxidative
phosphorylation
Electron transport chain - series of molecules (mainly proteins) that accept and donate electrons as they
pass from NADH/FADH2 to the final electron acceptor oxygen (which then combines with H+ and leaves
as water) releasing small amounts of energy along the way. It also pumps H+ ions from the matrix to the
intermembrane space, creating a hydrogen ion concentration gradient.
Chemiosmosis - is the movement of hydrogen ions (by the electron transport chain) to create a
hydrogen ion concentration gradient. This gradient creates a proton-motive force, which stores energy
that can be used to power ATP Synthase, an enzyme that combines ADP and a phosphate to form ATP.
Oxidative Phosphorylation - uses energy from the movement of electrons/hydrogen ions to add a
phosphate to a molecule of ADP, forming ATP. This produces roughly 32-34 molecules of ATP per 1
glucose.
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com
Name Answer Key
Date
Period
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com