Section 1
Cellular Energy
How Organisms Obtain Energy – Chapter 8
Transformation of Energy
 Energy is the ability to do work.
 Thermodynamics is the study of the flow and
transformation of energy in the universe.
Section 1
Cellular Energy
How Organisms Obtain Energy
Laws of Thermodynamics
 First law—energy can be converted from one
form to another, but it cannot be created nor
destroyed.
 Second law—energy cannot be converted
without the loss of usable energy.
Section 1
Autotrophs vs. Heterotrophs
Use light energy from
sun to make own food
Obtain energy from other
organisms
ALL ORGANISMS NEED ENERGY TO CARRY OUT
LIFE FUNCTIONS AND MUST RELEASE ENERGY
FROM SUGARS AND OTHER COMPOUNDS!!
Section 1
Cellular Energy
How Organisms Obtain Energy
 Metabolism - all of the chemical reactions in
a cell
 Two types of metabolic pathways
 1. Anabolic – Take in energy to build
large molecules
 2. Catabolic – Release energy when
breaking down large molecules
• Photosynthesis—light energy from the Sun
is converted to chemical energy for use by
the cell
• Cellular respiration—organic molecules are
broken down to release energy for use by
the cell
Adenosine Triphosphate (ATP)
One of principal chemical compounds that cells
use to store and release energy
Adenine
3 Phosphate groups
Ribose
(5-carbon sugar)
ATP
How is energy stored and released?
ATP
ADP
Energy
Adenosine Diphosphate
(ADP) + Phosphate
Partially
charged
battery
Energy
Adenosine Triphosphate (ATP)
Fully
charged
battery
What is ATP used for in the cell?
Photosynthesis
Process of turning light energy from the sun
into chemical energy
Section 2
Cellular Energy
Photosynthesis
Overview of Photosynthesis
 Photosynthesis occurs in two phases.
 Light-dependent reactions
 Light-independent reactions or the Calvin Cycle.
Photosynthesis: Overview
H2O
CO2
Light
NADP+
ADP + P
Lightdependent
reactions
Calvin
Calvin
cycle
Cycle
Chloroplast
O2
Sugars
Photosynthesis: Overview
LIGHT-DEPENDENT REACTIONS
Require light / use energy from light to produce oxygen
gas and convert ADP and NADP+ into the energy carriers
ATP and NADPH
CALVIN CYCLE
Does NOT require light / uses ATP and NADPH from
light-dependent reactions to produce high-energy sugars
that can be stored for a long time
Electron Carriers
When a potato is very hot, you wouldn’t dare grab it
with your bare hand, rather you use an oven mitt to
carry the potato. As the potato cools, you no longer
need the oven mitt.
This is similar to an electron carrier. Once an electron
receives energy from the sun, it is considered a “highenergy electron.” The electron does not travel on its
own from place to place. Another substance (in this case
NADP) carries the electron to its destination. As the
electron loses it’s high energy levels, it no longer needs
an electron carrier.
An electron carrier then is “a compound that can accept
a pair of high-energy electrons and transfer them, along
with most of their energy, to another molecule.”
Light-Dependent Reactions
ATP synthase
+ O2
2H2O
2 NADP+
2
ADP
2
NADPH
Calvin Cycle
12
6 ADP
12 ADP
12 NADPH
6
5-Carbon Molecules
Regenerated
12 NADP+
Section 2
Cellular Energy
Photosynthesis
Electron Transport
 Light energy excites electrons in the
photosystems and also causes a water
molecule to split, releasing an electron and
O2 is released as a waste product.
Section 2
Cellular Energy
Photosynthesis
Phase Two: The Calvin Cycle
 In the second phase of photosynthesis,
called the Calvin cycle, energy is stored
in organic molecules such as glucose.
Section 2
Cellular Energy
Photosynthesis
 CO2 molecules combine with a 6 carbon
molecule with an enzyme.
 The chemical energy stored in ATP and
NADPH is transferred to make a glucose
molecule.
Section 2
Cellular Energy
Photosynthesis
Alternative Pathways - in hot, dry environments
plants have adapted to a different way to
perform photosynthesis
 C4 plants – are able to make glucose in
different cells. Ex: Corn and sugarcane
 CAM plants – are able to make glucose at
different time of the day. Ex: Pineapples and
cati
Section 3
Cellular Energy
Cellular Respiration
Overview of Cellular Respiration
 Organisms obtain energy in a process called
cellular respiration.
 The equation for cellular respiration is the
opposite of the equation for photosynthesis.
Section 3
Cellular Energy
Cellular Respiration
 Cellular respiration occurs in three main parts.
 Glycolysis
 Krebs Cycle
 Electron Transport
Glycolysis
Process in which one molecule of glucose is
broken in half, producing pyruvic acid and
a small amount of energy in the cytoplasm
2 ATP
2 ADP
4 ADP
2NAD+
4 ATP
2
2 Pyruvic
acid
NET GAIN OF HOW MANY ATP MOLECULES?
Section 3
Cellular Energy
Cellular Respiration
Krebs Cycle
 Most of the energy from the glucose is still
contained in the pyruvate.
 The series of reactions in which pyruvate is
broken down into carbon dioxide is called the
Krebs cycle.
Section 3
Cellular Energy
Cellular Respiration
 The net yield from the Krebs cycle:
 6 CO2 molecules
 2 ATPs
 8 NADH
 2 FADH2
CoA
CoA
CO2
Krebs Cycle
NAD
FADH2
NADH
FAD
ATP
ADP
P
Section 3
Cellular Energy
Cellular Respiration
Electron Transport Chain
 Final step in the breakdown of glucose
 Point at which ATP is produced
 Produces about 24 ATP
Electron Transport Chain
Uses high-energy electrons from the Krebs
Cycle to convert ADP into ATP
Channel
ATP
synthase
ATP
Section 3
Cellular Energy
Cellular Respiration
Anaerobic Respiration
 The anaerobic pathway that follows glycolysis
 Two main types
 Lactic acid fermentation
 Alcohol fermentation
Cellular Respiration
Fermentation
Releases energy from food by producing
ATP in the absence of oxygen
WHY IS THIS IMPORTANT TO CELLS?
Two Types of Fermentation
ALCOHOLIC
Used by yeasts and microorganisms, producing alcohol
and carbon dioxide (as well as NAD+)
NO
OXYGEN!
NAD+
PRODUCED
LACTIC ACID
FOR BOTH!
Conversion of pyruvic acid into lactic acid (as well as
NAD+)
Chapter
Cellular Energy
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Chapter Diagnostic Questions
Formative Test Questions
Chapter Assessment Questions
Standardized Test Practice
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Chapter
Cellular Energy
Chapter Diagnostic
Questions
Which statement describes the law of
conservation of energy?
A.
B.
C.
D.
Energy cannot be converted or destroyed.
Energy can be converted and destroyed.
Energy can be converted but not destroyed.
Energy can be destroyed but not converted.
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Chapter Diagnostic
Questions
In which metabolic process are molecules
broken down to produce carbon dioxide and
water?
A. photosynthesis
B. cellular respiration
C. homeostasis
D. fermentation
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Chapter Diagnostic
Questions
At the end of the Calvin cycle, where is energy
stored?
A. NADPH
B. ATP
C. chloroplast
D. glucose
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Section 1 Formative
Questions
Which law of thermodynamics explains why the
ladybug receives the least amount of usable energy?
A. the first law of thermodynamics
B. the second law of thermodynamics
1.
2.
A
B
Chapter
Cellular Energy
Section 1 Formative
Questions
All of the energy from the
food you eat comes from
the sun.
A. true
B. false
1.
2.
A
B
Chapter
Cellular Energy
Section 1 Formative
Questions
Why is cellular respiration a catabolic pathway?
A. Energy is used to form glucose and oxygen.
B. Energy is converted from water to carbon
dioxide.
C. Energy that is lost is converted to thermal
1.
energy.
2.
3.
D. Energy is released by the breakdown of4.
molecules.
A
B
C
D
Chapter
Cellular Energy
Section 1 Formative
Questions
Why is adenosine triphosphate (ATP) such an
important biological molecule?
A. It captures light energy from the sun.
B. It is produced in anabolic pathways.
C. It stores and releases chemical energy.
D. It converts mechanical energy to thermal
energy.
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Section 2 Formative
Questions
Where in the plant cell does
photosynthesis take place?
A. chloroplasts
B. Golgi apparatus
C. mitochondria
D. vacuoles
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Section 2 Formative
Questions
Which range of
wavelengths is reflected
by chlorophylls a and b?
A. 400-500 nm
B. 500-600 nm
C. 600-700 nm
1.
2.
3.
A
B
C
Chapter
Cellular Energy
Section 2 Formative
Questions
Which mechanism of photosynthesis uses
the movement of hydrogen ions (H+) across
a concentration gradient to synthesize ATP?
A. absorption
B. chemiosmosis
C. electron transport
D. C2 pathway
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Section 2 Formative
Questions
How are the C4 pathway and the CAM pathway
an adaptive strategy for some plants?
A. They accelerate photosynthesis.
B. They release more oxygen.
C. They help the plant conserve water.
D. They reduce the requirement for ATP.
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Section 3 Formative
Questions
What is the overall purpose of cellular
respiration?
A. to make ATP
B. to process H2O
C. to store glucose
D. to deliver oxygen
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Section 3 Formative
Questions
Which represents the general sequence of
cellular respiration?
A. TCA cycle  chemiosmosis  glycolysis
B. glycolysis  Krebs cycle  electron transport
C. electron absorption  catalysis 
phosphorylation
D. aerobic pathway  anaerobic pathway 
fermentation
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Section 3 Formative
Questions
Which stage of cellular respiration is the
anaerobic process?
A. glycolysis
B. Krebs cycle
C. electron transport
1.
2.
3.
A
B
C
Chapter
Cellular Energy
Section 3 Formative
Questions
Which molecule
generated by the Krebs
cycle is a waste product?
A. CoA
B. CO2
C. FADH2
D. NADH
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Chapter Assessment
Questions
Look at the following figure.
Which part of the chloroplast
is a sac-like membrane
arranged in stacks?
A. grana
B. stroma
C. thylakoids
D. Golgi apparatus
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Chapter Assessment
Questions
During the Krebs cycle,
pyruvate is broken down
into what compound?
A. H2O
B. O2
C. CO
D. CO2
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Chapter Assessment
Questions
Look at the following figure.
Which molecule is released
when ATP becomes ADP?
A. phosphate group
B. water molecule
C. ribose sugar
D. energy cells
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Standardized Test
Practice
Which metabolic process is photosynthesis?
A
1.
2.
B
A
B
Chapter
Cellular Energy
Standardized Test
Practice
At the beginning of photosynthesis, which
molecule is split to produce oxygen (O2) as
a waste product?
A. CO2
B. H2O
C. C6H12O6
D. 3-PGA
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Standardized Test
Practice
Which molecule helps provide the energy that
drives this cycle?
A. 3-PGA
B. CO2
C. NADPH
D. rubisco
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Standardized Test
Practice
Which product of the Calvin cycle is used for
the production of glucose and other organic
compounds?
A. ADP
B. CO2
C. G3P
D. NADP+
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Standardized Test
Practice
What is the final step of cellular respiration?
A. O2 and H+ form H2O.
B. Electrons and H2O generate ATP.
C. C6H12O6 is broken down into CO2.
D. NADH and FADH2 gain electrons.
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Standardized Test
Practice
What prevents pyruvate from
entering the Krebs cycle and
instead results in this pathway?
A. a buildup of CO2
B. a lack of oxygen
C. an excess of glucose
D. an increased demand for ATP
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Standardized Test
Practice
Which is not a process that occurs in both
cellular respiration and glycolysis?
A. chemiosmosis
B. electron transport
C. glycolysis
D. production of G3P
1.
2.
3.
4.
A
B
C
D
Chapter
Cellular Energy
Glencoe Biology Transparencies
Chapter
Cellular Energy
Image Bank
Section 1
Cellular Energy
Vocabulary
Section 1
energy
thermodynamics
metabolism
Photosynthesis
cellular respiration
adenosine triphosphate (ATP)
Section 2
Cellular Energy
Vocabulary
Section 2
thylakoid
granum
stroma
pigment
NADP+
Calvin cycle
rubisco
Section 3
Cellular Energy
Vocabulary
Section 3
anaerobic process
aerobic respiration
aerobic process
glycolysis
Krebs cycle
fermentation
Chapter
Cellular Energy
Animation
 ATP
 The Calvin Cycle
 Visualizing Electron Transport
 The Krebs Cycle (Citric Acid Cycle)
Chapter
Cellular Energy
Chapter
Cellular Energy
Chapter
Cellular Energy