AP Biology
Chapter 9 Guided Reading Assignment
Name ____Ryan Hanssens_______
Hint: review the concept check questions – these are great quick quiz questions!
1. Define the two catabolic pathways:
a. Fermentation – a partial degradation of sugars that occurs without the use of
oxygen
b. Cellular respiration – when oxygen is consumed as a reactant along with the
organic fuel; most efficient catabolic pathway; mitochondria house most of the
metabolic equipment needed
2. Use the following terms correctly in a sentence: redox reactions, oxidation,
reduction, reducing agent and oxidizing agent.
In redox reactions, oxidation (the loss of electrons from one substance) and
reduction (the addition of electrons to another substance) occur. A reducing agent
is the electron donor and the oxidizing agent is the electron acceptor.
3. Why is being “reduced” equivalent to having a greater potential energy?
As electron loses potential energy when it shifts from a less electronegative atom
toward a more electronegative one.
4. In cellular respiration, what is being oxidized and what is being reduced?
oxidized – glucose ; reduced - oxygen
5. Label the diagram below of the electron movement with regard to the coenzyme
NAD+.
CH2
O
O P OO
O P OO
Page 1 of 7
6. Why are electron transport chains an advantage to living systems?
they break the fall of electrons too oxygen into several energy releasing steps
instead of one explosive reaction
7. What are the three stages of aerobic cellular respiration?
Glycolysis, the citric acid cycle, oxidative phosphorylation: electron transport and
chemiosmosis
8. What is substrate-level phosphorylation?
when a small amount of ATP is formed directly in a few reactions of glycolysis and
the citric acid cycle
9. Complete the chart below re: glycolysis
Energy Investment phase
Glucose
2 ADP + 2 P
2 ATP used
Energy payoff phase
4 ADP + 4 P
4 ATP Formed
2 NAD+ + 4e- + 4 H+
2 NADH + 2 H+
2 Pyruvate + 2 H2O
Net
Glucose
4 ATP formed – 2 ATP used
2 NAD+ + 4e- + 4H+
2 Pyruvate + 2 H2O
2 ATP
2 NADH + 2 H+
10. Label the transition reaction converting pyruvate to acetyl coA below:
Page 2 of 7
CYTOSOL
MITOCHONDRION
NAD+
NADH
+ H+
O
C
O
C
O
S
CoA
C
O
CH3
CH3
PYRUVATE
ACETYL CoA
CO2
Coenzyme A
Transport Protein
11. Label the citric acid cycle below:
+
a. Where does the C “go” that is removed?
it is released as a waste product in the form of CO2
Page 3 of 7
b. What is happening when NAD+  NADH + H+?
NAD+ is oxidized reducing it to NADH
c. Where is substrate level phosphorylation happening?
step 5
12. What is oxidative phosphorylation?
the synthesis of ATP by phosphorylation of ADP for which energy is obtained by
electron transport and which takes place in the mitochondria during aerobic
respiration
13. What are cytochromes?
It is an iron containing protein that transports electrons by accepting and donating
electrons. The last cytochrome passes its electrons to oxygen
14. Define chemiosmosis and label the diagram below.
chemiosmosis:
INTERMEMBRANOUS SPACE
H+
H+
H+
H+
H+
H+
H+
Chemiosmosis- process in which energy
stored in the form of a hydrogen ion
gradient across a membrane is used to
drive cellular work such as the synthesis of
ATP
H+
ADP
+
P
ATP
MITOCHONDRIAL MATRIX
Page 4 of 7
15. Label the diagram below of the activities occurring on the ECT.
16. Complete the summary diagram of cellular respiration. You are responsible for
these #’s and locations!
Page 5 of 7
17. Label the diagram of fermentation below:
18. Does aerobic cellular respiration happen in prokaryotic organisms – if yes –
where?
yes - cytoplasm
19. What is the overall purpose of fermentation? Why does it have to occur?
fermentation is a pathway used under anaerobic conditions. it is needed to
produce energy or ATP where there is no oxygen present. its products are yeast,
alcohol, the fermentation of many foods, and lactic acid in muscles
20. What is a facultative anaerobe?
organisms that make enough ATP to survive using either fermentation or
respiration – yeast and many bacteria
21. What is the evolutionary significance of glycolysis?
Ancient prokaryotes most likely used glycolysis to make ATP long before oxygen
was present in Earth’s atmosphere, since glycolysis does not require oxygen.
Also, glycolysis is the most widespread metabolic pathway, suggesting that it
evolved very early in the history of life on earth. It’s cytosolic location implies
antiquity because the pathway doesn’t require any membrane-bounded organelles
of eukaryotic cells.
Page 6 of 7
22. Why do fats provide a little more than twice as many calories per gram as
compared to carbohydrates or proteins? Hint: Think of the output of the Citric Acid
Cycle.
there is a greater change in the oxidation of the carbon atom found in fatty acids
more than proteins and carbs.
23. Why would AMP stimulate cellular respiration and ATP inhibit it?
Since the purpose of cellular respiration is to produce ATP, when a cell senses
that it has lots of ATP, it will reduce the amount of cellular respiration it's
performing. When a cell senses that it has lots of AMP it tells the cell that it's used
up a lot of ATP and therefore needs to make more.
24. Why would phosphofructokinase being allosteric in character be an advantage to
the control of cellular respiration?
When there is too much of one thing then it will go slower, it gets backed up.
When an enzyme gets caught up in a lot of work it works slower and inefficiently.
So when there is already enough work an ATP will bind to the inhibiting site on the
allosteric phosphofructokinase to signal that it can slow down glycolysis. It helps
cellular respiration because it allows it to go more smoothly and effectively. AMP
works the opposite way by speeding it up.
Page 7 of 7