CELLULAR RESPIRATION WORKSHEET: HIGHER LEVEL
1
8.1.1: REDOX Reactions
1. Cellular respiration consists of a series of REDOX reactions, in which electrons are
transferred. What are the differences between oxidation and reduction?
OXIDATION
REDUCTION
The following is a generalised formula for a redox reaction:
A- + B  A + B-
Draw an arrow to explain which part of the reaction is oxidised and which part is reduced.
Compound A/B is the reducing agent and Compound A/B is the oxidising agent.
2. When compounds lose electrons, they gain/lose energy. When compounds gain
electrons, they gain/lose energy.
3.
Redraw the chemical formula for cellular respiration of glucose, and annotate
(indicate) which compounds/ molecules are oxidised and which are reduced.
4. Name two compounds which are important ‘electron carriers’ during cellular
respiration.
RESPIRATION AND GLYCOLYSIS - DEFINITIONS
5. Write the overall equation for cellular respiration
2
6. Where in the cell does the glycolysis part of cellular respiration take place? Why?
7. What is the literal meaning of the word glycolysis?
8. Write the overall equation for glycolysis in words and in chemical formulae
3
9. Complete the cellular respiration CONCEPT MAP
Cellular respiration
4
10. Identify the key molecules involved in cellular respiration
A.
B.
C.
D.
E.
F.
G.
H.
5
GLYCOLYSIS – UNDERSTANDING THE REACTION
Use the following links to help you work through this section:

Step-by-step through glycolysis:

http://programs.northlandcollege.edu/biology/Biology1111/animations/glycolysis
.html

Hartnell
Tutorial
on
Glycolysis
(includes
animation
of
glycolysis):
http://www.hartnell.edu/tutorials/biology/cellularrespiration.html

Virtual
cell:
Glycolysis
overview:
http://vcell.ndsu.edu/animations/glycolysis_overview/movie-flash.htm

Virtual
Cell
Glycolysis:
The
reactions:
http://vcell.ndsu.edu/animations/glycolysis_reactions/advanced.htm

McGraw
Hill
animation
on
Glycolysis:
http://highered.mcgraw-
hill.com/sites/9834092339/student_view0/chapter7/how_glycolysis_works.html

McGraw
Hill
animation
on
NAD+:
http://highered.mcgraw-
hill.com/sites/9834092339/student_view0/chapter7/how_the_nad__works.html
11. Explain how phosphorylation, lysis and oxidation reactions are involved in ATP
formation through the process of glycolysis:
1. Substrate-level Phosphorylation:
2. Lysis
3. Oxidation
6
4. ATP formation
12. What is the ‘energy investment’ phase of glycolysis? How many ATP are changed to
ADP in the early reactions of glycolysis?
13. What is the ‘energy payoff phase of glycolysis? How many ATP are made from ADP
in the later reactions of glycolysis?
14. What is the ‘net production’ (in numbers of molecules) of ATP from glycolysis?
15. How many molecules of pyruvate (pyruvic acid) are made from a single glucose
molecule?
16. What is NAD+? What does it do and what is it transformed into? Why is a supply of
NAD+? required for glycolysis?
FERMENTATION
1. Identify the reactants and products involved in lactic acid and alcohol
7
fermentation
A.
B.
C.
D.
E.
2. Where in the cell and why does the process of fermentation take place?
3. Explain how lactate acid fermentation begins with pyruvate and yields lactate.
Explain how NAD+ is recycled during this process, and why this is important.
4. Explain how alcohol fermentation begins with pyruvate and yields ethanol and carbon
dioxide.
Explain how NAD+ is recycled during this process, and why this is
important.
8
MITOCHONDRIAL STRUCTURE
1. Label the diagrams of a mitochondrion below:
9
AEROBIC RESPIRATION
SYLLABUS ASSESSMENT STATEMENTS:
• 8.1.4: Explain aerobic respiration: the Link reaction, the Krebs cycle, the role of
NADH + H+, the electron transport chain and the role of oxygen
• 8.1.5: Explain oxidative phosphorylation in terms of chemiosmosis
RESOURCES:
Krebs Cycle:
 http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter25/animation__how_the_krebs_cyc
le_works__quiz_1_.html
 A slow walk through the Krebs cycle:
http://www.wiley.com/legacy/college/boyer/0470003790/animations/tca/tca.htm
10
THE LINK REACTION AND THE KREBS CYCLE
The Citric Acid (Krebs) Cycle takes place in the ___________________________________.
Pyruvic acid is chemically groomed for the Krebs cycle
Each pyruvic acid molecule is broken down to form ________ and a two-carbon
molecule called ____________________________, which enters the Krebs cycle
The Krebs cycle generates many _____________and ___________molecules
11
The Krebs cycle is a series of reactions in which enzymes strip away electrons and
H+ from each acetyl group
So what do you need to know about the Krebs Cycle?
In
Out
Each “turn” produces two __________ molecules.
Oxaloaetic acid is a product that is made in the cycle which helps keep the cycle
going.
Complete the table for the products of the Krebs cycle:
Substance
NAD+
Oxidised/Reduced/neither
Reason
NADH
FAD
FADH2
For the Krebs cycle, calculate the production of the following for each cycle:

ATP

FADH2

NADH
12
ELECTRON TRANSPORT CHAIN, OXIDATIVE PHOSPHORYLATION AND
CHEMIOSMOSIS
WATCH AND USE THE FOLLOWING ANIMATIONS:
 http://vcell.ndsu.nodak.edu/animations/etc/index.htm
 http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter25/animation__electron_transp
ort_system_and_atp_synthesis__quiz_1_.html
Explain in your own words:
1. The electron transport chain: its location, and the key carrier molecules
2. The connection
phosphorylation
between
the
electron
transport
chain
and
oxidative
3. The process of chemiosmosis
SUMMARY OF ATP PRODUCTION IN CELULAR RESPIRATION
13
Complete the following table:
Process
Glycolysis
ATP used
ATP produced
Net ATP gain
Krebs cycle
Electron transport
chain and
chemiosmosis
TOTAL
Complete the table linking the structures of the mitochondrion, and how these sites
allow cellular respiration:
Outer mitochondrial
membrane
Matrix
Cristae
Inner mitochondrial
membrane
Space between inner and
outer membranes
14
HL Past paper Questions
1. Explain the link reaction that occurs between glycolysis and the Krebs cycle (4 marks).
2.
The electron micrograph below shows an organelle in a eukaryotic cell. What is the
area labelled X and what is the type of reaction occurring there?
[Source: http://scienceblogs.com/clock/2006/11/cell_structure.php]
X
Reaction
A.
matrix
photolysis
B.
stroma
Krebs cycle
C.
stroma
photolysis
D.
matrix
Krebs cycle
(Total 1 mark)
3.
What is chemiosmosis?
A.
Coupling of ATP synthesis to the electron transport and proton movement
B.
Phosphorylation of glucose in the mitochondrial matrix
C.
H+ ions moving down a concentration gradient into the mitochondrial matrix
D.
Activation of ATPase in order to synthesize ATP
(Total 1 mark)
15
CORE QUESTIONS
1.
The diagram below shows a biochemical pathway in a yeast cell. Which of the
following correctly identifies a compound in the diagram? Explain your answer
A.
I is fat.
B.
II is pyruvate.
C.
III is lactate.
D.
IV is carbon dioxide.
16
2.
Humans can respire aerobically and anaerobically. Which are products of both
aerobic cell respiration and anaerobic cell respiration in humans? Explain your
answer
A.
Pyruvate and ATP
B.
Pyruvate and lactate
C.
ATP and carbon dioxide
D.
Lactate and carbon dioxide
(Total 1 mark)
3.
Compare how pyruvate is used in human cells when oxygen is available and when
oxygen is not available.
(5 marks)
4. Outline the process of glycolysis.
(5)
17
2.
Investigators carried out experiments to find the relationship between the energy
used by mice (the metabolic rate) and their activity. They found that the amount of
time mice are active depends on the time of day, whether they are single or in groups
and on the temperature of their surroundings. The bar chart below shows the
percentage of time mice were active during three-hour periods at three different
temperatures.
[Source: L E Mount and J V Willmott. 1967. Journal of Physiology. Vol 190. Pp 371–380. Published
by Wiley-Blackwell. Used with permission]
18
19
(a)
Calculate how many minutes the group mice are active between 21:00 and
00:00 at 8 °C.
.......................................................................................................................
(1)
(b)
Outline the relationship between activity and temperature from 21:00 to 03:00
in all of the mice.
.......................................................................................................................
.......................................................................................................................
(1)
(c)
Animals which are active at night are nocturnal. Suggest one advantage for
mice being nocturnal.
.......................................................................................................................
.......................................................................................................................
(1)
20
The investigators also found that the metabolic rate of the mice changed at different
times of the day. Mice were kept at one of the three constant temperatures for 24
hours and their oxygen consumption was measured. The graph below shows the
results for single mice and the mean values for group mice.
[Source: L E Mount and J V Willmott. 1967. Journal of Physiology. Vol 190. Pp 371–380. Published
by Wiley-Blackwell. Used with permission]
(d)
State the relationship between temperature and metabolic rate.
.......................................................................................................................
(1)
21
(e)
Compare the results for the single mice at 15 °C with those for the group mice
at 15 °C.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
(2)
(f)
Suggest one reason why the results differ for single mice and group mice.
.......................................................................................................................
.......................................................................................................................
(1)
(g)
Explain why oxygen consumption is used as a measure of metabolic rate.
.......................................................................................................................
.......................................................................................................................
(2)
(h)
Using the data from both graphs, evaluate the hypothesis that increased
activity causes an increase in metabolic rate in mice.
.......................................................................................................................
.......................................................................................................................
(2)
(Total 11 marks)
3. Explain the production of energy during aerobic respiration from pyruvate that has
22
been produced by glycolysis.
(8)
23