AP Biology
Objectives and Study Guidelines
Cellular Respiration
Vocabulary Ch. 9
Fermentation
Redox reactions
Reducing agent
aerobic respiration
oxidation
oxidizing agent
Electron transport chain glycolysis
Acetyl CoA
cytochromes
Chemiosmosis
ATP synthase
Proton-motive force
alcoholic fermentation
Obligate anaerobes
facultative anaerobes
cellular respiration
reduction
NAD+
citric acid cycle
oxidative phosphorylation
substrate-level phosphorylation
lactic acid fermentation
beta oxidation
Essential Questions
 In what ways do all living systems require a constant input of free energy?
 How do organisms capture and store free energy for use in biological processes?
 How do interactions between molecules affect their structure and function?
Key Ideas and Study Guidelines
 Aerobic respiration: glycolysis  Krebs cycle  oxidative phosphorylation  36 ATP
 Anaerobic respiration: glycolysis  regenerate NAD+  much less ATP
 Oxidative phosphorylation results in the production of large amounts of ATP from
NADH and FADH2.
 Chemiosmosis is the coupling of the movement of electrons down the electron
transport chain with the formation of ATP using the driving force provided by the
proton gradient.
 During glycolysis, know the reactants (glucose, ADP + Pi, NAD+) and products (two
pyruvate, two NADH, and net gain of two ATP molecules). Understand that the net
gain of 2 ATP is a result of substrate-level phosphorylation are available for cellular
work, and the NADH can be converted to ATP in the mitochondria.
 In the oxidation of pyruvate, understand that the process occurs twice per glucose
molecule, that the NADH can be converted to ATP, and that the CO2 is released
from the cell and ultimately from the organism.
 In the Krebs cycle (citric acid cycle), understand what goes into the cycle and what
comes out and that the process occurs twice per glucose. Each pyruvate dropped
into the Krebs cycle produces: 4NADH, 1 FADH2, 1 ATP, and 2 CO2. Therefore, all
the pyruvate obtained from the original glucose molecule produces: 8 NADH, 2
FADH2, and 2 ATP. Understand that the NADH and FADH2 can be converted to
ATP by chemiosmosis, and that the CO2 is released from the cell and ultimately
from the organism.
 Each NADH  3 ATP
 Each FADH2  2 ATP
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½ O2 is the final electron acceptor of the electron transport chain, and the chain will
not function in the absence of oxygen.
Oxidative phosphorylation serves the important function of regenerating NAD+ so
that glycolysis and the Krebs cycle can continue.
Chemiosmosis occurs in photosynthesis as well as respiration.
During fermentation understand why fermentation occurs, as well as what goes in
and what comes out. Be able to explain why fermentation produces less ATP than
aerobic respiration. Yeast, fungi, and bacteria produce ethanol; humans produce
lactic acid (only during O2 deficit).
ATP is continually hydrolyzed and regenerated in a cell so that energy is available
for various cellular processes.
Both H+ and electrons are transferred to electron carriers in most redox reactions;
the exception to this is the electron transport chain.
Describe the synthesis of ATP by chemiosmosis and understand that most ATP in
cells is generated by oxidative phosphorylation.
Explain the relationship between cellular respiration and photosynthesis, and the
role of ATP and coenzymes in both processes.
While carbohydrates are a major source of starting molecules for ATP synthesis,
proteins, lipids, and nucleic acids can also be broken down into intermediates, that
can enter cellular respiration and contribute to ATP synthesis, though to a lesser
extent.
Big Ideas
 Big Idea 2: Biological systems utilize free energy and molecular building blocks to
grow, to reproduce, and to maintain dynamic homeostasis.
Enduring Understandings
 EU 2.A: Growth, reproduction and maintenance of the organization of living
systems require free energy and matter.
 EU 2.B: Growth, reproduction and dynamic homeostasis require that cells create
and maintain internal environments that are different from their external
environments.
 EU 4.A: Interactions within biological systems lead to complex properties.
Essential Knowledge
 EK 2.A.1: All living systems require constant input of free energy.
 EK 2.A.2: Organisms capture and store free energy for use in biological processes.
 EK 2.B.2: Growth and dynamic homeostasis are maintained by the constant
movement of molecules across membranes.
 EK 4.A.1: The subcomponents of biological molecules and their sequence determine
the properties of that molecule.
Learning Objectives
 LO 2.1: The student is able to explain how biological systems use free energy based
on empirical data that all organisms require constant energy input to maintain
organization, to grow and to reproduce. (SP 6.2)
 LO 2.2: The student is able to justify a scientific claim that free energy is required
for living systems to maintain organization, to grow or to reproduce, but that
multiple strategies exist in different living systems. (SP 6.1)
 LO 2.3: The student is able to predict how changes in free energy availability affect
organisms, populations, and ecosystems. (see SP 6.4)
o Can you describe the use of biological processes to offset entropy and
maintain or increase order?
 Coupling of cellular processes that increase entropy with those that
decrease entropy
 Energy input must exceed free energy lost to maintain order and
power cells.
 ATP ADP coupled with other processes
 Krebs cycle
 Glycolysis
 Calvin cycle
 Fermentation
o Can you explain how free energy is used to maintain organization, growth,
and reproducing?
 Endothermy (maintaining homeostasis)
 Ectothermy (maintaining body temperature)
 Elevated floral temperature in some plant species
 Seasonal reproduction in animals and plants
 Life –history strategies (biennial, reproductive diapause)
 Size of an organisms verseus metabolic rate
 Energy storage
o Can you explain how changes in available energy can effect population size or
disrupt an ecosystem?
 Energy pyramid
 Number of producers
 Trophic levels
 Available resources such as sunlight
 LO 2.4: The student is able to use representations to pose scientific questions about
what mechanisms and structural features allow organisms to capture, store, and use
free energy. (SP 1.4, 3.1)
 LO 2.5: The student is able to construct explanations of the mechanisms and
structural features of cells that allow organisms to capture, store, or use free energy.
(SP 6.2)
o Can you give examples and describe how organisms capture, store, and use
free energy?
Photosynthesis (know the detailed steps of light reactions,
Photosystem I and II, locations, know general process of Calvin Cycle
but not all steps and the only enzyme needed is ATP synthase.
 Chemosynthesis
 Heterotrophs hydrolysis of carbohydrates, lipids, and proteins.
 Fermentation (names of enzymes and intermediates of the pathway
are not necessary)
 Electron acceptors (NADP+ in photosynthesis and oxygen in cellular
respiration)
o Can you explain the role of photosynthetic prokaryotes (bacteria) in creating
an oxygenated atmosphere and as the pathway of eukaryotic photosynthesis?
 Endosymbiotic theory
o Can you describe in detail the process of cellular respiration from the
breakdown of carbohydrates, to the enzyme-catalyzed reactions that harvest
energy?
 Glycolysis, Krebs Cycle and ETC (memorization of the steps in
glycolysis and Krebs cycle, structure of molecules and names of
enzymes are not necessary, for ETC know details).
 ATP ADP coupled reaction
LO 2.12: The student is able to use representations and models to analyze
situations or solve problems qualitatively and quantitatively to investigate whether
dynamic homeostasis is maintained by the active movement of molecules across
membranes. (SP 1.4)
LO 4.1: The student is able to explain the connection between the sequence and the
subcomponents of a biological polymer and its properties. (SP 7.1)
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