CyberEd® Student Study Guide
Photosynthesis
CyberEd® Student Study Guide: Photosynthesis
The following National Science Education Life Science Content Standards specifically relate to this
study guide:
o
o
o
PHOTOSYNTHESIS
Plant cells contain chloroplasts, the site of photosynthesis.
Plants and many microorganisms use solar energy to combine molecules of carbon dioxide and
water into complex, energy rich organic compounds and release oxygen to the environment.
This process of photosynthesis provides a vital connection between the sun and the energy
needs of living systems.
Table of Contents
Introduction to Photosynthesis ...................................................................................................................... 2
Properties of Light and Photosynthetic Pigments ......................................................................................... 4
Photosynthesis: The Process....................................................................................................................... 7
Photosynthesis Alternatives ........................................................................................................................ 13
Photosynthetic Products ............................................................................................................................. 16
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© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Introduction to Photosynthesis
Introduction to Photosynthesis
Now load the CyberEd Biology Course Title: Photosynthesis
View scenes 1 –5 and complete the exercise below.
Multimedia
Presentation
A review of autotrophs, producers, photosynthesis, and aerobic
respiration.
Scene 2
1. Define autotroph. What is another name for autotrophs?
An autotroph is an organism that produces its own food, also known as a producer.
2. What is a consumer?
A consumer is an organism that gets its food from other organisms, either other consumers or producers.
Scene 3
3. Answer the following questions on energy conversion by photosynthetic organisms.
STEP 1
STEP 2
STEP 3
Photosynthetic organisms use what form of available energy?
Photosynthetic organisms transfer gathered energy to what other form
of energy?
What is the molecule that contains this energy?
What compounds do photosynthetic organisms use the transferred
energy to form?
Sun (light)
Chemical energy
ATP
Glucose mainly
Scene 4
4. Identify the following in the diagram of the leaf: stomata, O2, H2O, and CO2.
A.
B.
C.
D.
5. Where do plants acquire…
water?
glucose?
CO2?
6. Why is glucose important in plants?
Glucose is an energy storage molecule for the plant that enables it to grow and survive. Also used in the
formation of ATP.
Page 2
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Scene 5
7. Why is glucose important in aerobic respiration?
Glucose is broken down to produce ATP that provides energy for a variety of cellular tasks.
8. Fill the table comparing Photosynthesis and Aerobic Respiration.
Photosynthesis
INPUT
(Substrates)
OUTPUT
(Products)
Aerobic Respiration
Required molecules
Carbon dioxide
Water
Oxygen
Required Energy Source
ATP and/or light
Glucose
Released molecules
Oxygen
Carbon dioxide
Water
End Energy Product
Glucose
ATP
Quiz: Plants and Photosynthesis
Please take the quiz provided by your teacher.
Quiz
Page 3
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Properties of Light and Photosynthetic Pigments
Properties of Light and Photosynthetic Pigments
Now load the CyberEd Biology Course Title: Photosynthesis
View scenes 6 – 10 and complete the exercises below.
Multimedia
Presentation
Scene 6
1. What is the visible spectrum? Why does it appear white?
The visible spectrum is all the wavelengths that can be detected by the naked eye. The light appears
white because it is a blend of all the wavelengths and until light is absorbed by, reflected off, or refracted
through an object, no color can be seen.
2. What are photons?
Photons are particles of light, delivering a discrete quantity of energy.
3. What is the relationship between the wavelength of light and the amount of energy it contains?
The shorter the wavelength, the more energy in the photons.
4. Which line has more energy?
5. Put the following colors in order by wavelength, starting with highest energy to the lowest: Red, Blue,
Green, Yellow, Violet, and Orange.
Violet, Blue, Green, Yellow, Orange, Red
Scene 7
6. As demonstrated in the following illustrations, what are the possible outcomes when light meets an
object? Which one is necessary for photosynthesis to occur?
A.
B.
C.
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© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Scene 8
7. Name the three main photosynthetic pigments.
Chlorophyll a, Chlorophyll b, carotenoids
8. Why do leaves appear green?
The photosynthetic pigment chlorophyll reflects light in the green part of the visible spectrum and absorbs
light from the red, blue and violet part of the spectrum.
Scene 9
9. Why is it beneficial for a plant to contain different photosynthetic pigments?
It allows the plant to exploit a variety of wavelengths for energy absorption.
Scene 10
10. Where are the photosynthetic pigments found in plant cells?
Chloroplasts, thylakoid membrane
11. Identify the following structures of the chloroplast: thylakoid lumen, inner chloroplast membrane,
outer chloroplast membrane, granum, stroma, and thylakoid.
A.
B.
C.
D.
E.
F.
Light and Pigments
Please load the CyberEd Biology Course Title: Photosynthesis
Complete Interactive Lessons #1 – 3.
Interactive
Lesson
A review of the properties of light, photosynthetic pigments, and the
role of chloroplasts.
Page 5
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Pigments, Absorption, and Spectra
Now load the MSS Intermediate Biology Simulation: Photosynthesis
View section A: screens #1 – 6.
Computer
Simulation
Quiz: Characteristics of Light
Please take the quiz provided by your teacher.
Quiz
Quiz: Chloroplasts and Pigments
Please take the quiz provided by your teacher.
Quiz
Quiz: The Antenna Complex
Please take the quiz provided by your teacher.
Quiz
Page 6
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Photosynthesis: The Process
Photosynthesis Overview and Light Reactions
Now load the CyberEd Biology Course Title: Photosynthesis
View scenes 11 –17 and complete the exercises below.
Multimedia
Presentation
Scene 11
1. Fill in the table comparing the light and dark reactions of photosynthesis.
Light Reaction
Dark Reaction
Also Known As
Light Dependent Reaction
Light Independent Reaction
Within the chloroplast, where do
the reactions occur?
Thylakoid membranes
Stroma
What molecules are required?
Water
Carbon Dioxide, ATP,
NADPH
What molecules are produced?
Oxygen, ATP, NADPH
Glucose
2. True/False.
The dark reactions must take place in the dark.
The light reactions must take place in the light.
Both reactions occur in the chloroplast.
Scene 12
3. Identify each structure in the diagram and describe its function. Choose from the following:
Chlorophyll a, Reaction Center, Antenna Assembly, Photosystem, and Primary Electron Acceptor.
Structure
A
Primary Electron
Acceptor
B
Reaction Center
C
Antenna
Assembly
D
Chlorophyll a
E
Photosystem
Page 7
Function
Structure that receives the first
electron released from
chlorophyll a.
A special pigment structure that
receives energy and relays an
electron.
A structure of hundreds of
photosynthetic pigments within
the thylakoid membrane.
Pigment found in the thylakoid
membrane.
Made up of three structures that
absorb and relay energy and
electrons.
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Scene 13
4. What is the difference in the electron path between Photosystem I and Photosystem II? In which
photosystem does non-cyclic electron flow originate?
The path of electrons leaving the primary electron acceptor is cyclic in Photosystem I and non-cyclic in
Photosystem II. Non-cyclic electron flow uses both photosystems, but the electron originates in
Photosystem II.
5. What happens to the components of water (H2O) during Photosystem II activity? Which components
are required for Photosystem II to function and which components are by-products?
The hydrogen and oxygen atoms are split by light energy. Electrons are removed from water and used to
replace electrons in the reaction center. Hydrogen ions, or protons, remain in the lumen. Oxygen is
released from the plant via stomata. Electrons are required by Photosystem II, and protons and water are
by-products.
Scene 14 - 15
6. In the diagram of noncyclic electron flow, identify the following structures and answer the questions
related to each structure:
A.
How is the proton gradient produced within this space?
Electron transport chain, as electrons drop through the chain, they give off little bits of energy that are
used to pump protons from the stroma into the lumen.
Splitting water also produces protons.
How do the protons reduce the gradient?
Protons move across the membrane through proton channels.
B.
What is the function of this protein? How does it work?
This enzyme acts as a channel for protons to diffuse back into the stroma. The movement of protons
through the channel helps power the enzyme to produce ATP from ADP.
C.
What is the function of this protein? How does it work?
This enzyme converts NADP+ to NADPH. It receives an electron from Photosystem I and attaches it to
the NADP+ molecule.
Page 8
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Scene 15
7. Where do the electrons come from that will replace those liberated in the reaction center of
Photosystem II?
Water
8. In noncyclic electron flow, Photosystem I donates an electron when light energy is passed to the
reaction center. Where do the electrons come from that will replace the electrons donated in
Photosystem I reaction center?
Electrons come from Photosystem II and the electron transport chain.
9. Noncyclic electron flow produces what two molecules?
ATP and NADPH
Scene 16
10. In cyclic electron flow where does the electron come from that will fill the electron vacancy in the
reaction center of Photosystem I?
The electron is from the reaction center of Photosystem I.
11. In the following diagram of cyclic electron flow identify the following components: lumen, stroma,
ATP synthase, proton pump, and electron transport chain.
A.
B.
C.
D.
E.
Scene 17
12. Fill in the table comparing cyclic and noncyclic electron flow.
Noncyclic Electron Flow
Cyclic Electron Flow
Molecules produced
ATP and NADPH
ATP
Enzymes to produce molecules
ATP synthase & NADPH
reductase
ATP synthase
Photosystems involved
Photosystems I and II
Photosystem I
Source of electron replacements in
photosystems
Water, Reaction Center of
Photosystem II
Reaction Center of
Photosystem I
Does the process use water?
Yes
No
Page 9
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Light Dependent Reactions (Light Reactions)
Now load the MSS Intermediate Biology Simulation: Photosynthesis
View section B: screens 1 - 5.
Computer
Simulation
Light Reactions
Please load the CyberEd Biology Course Title: Photosynthesis
Complete Interactive Lessons #4 and 5.
A review of the flow of electrons in the Light Reactions.
Interactive
Lesson
Quiz: The Light Reactions
Please take the quiz provided by your teacher.
Quiz
Quiz: Light Reactions and Electron Flow
Please take the quiz provided by your teacher.
Quiz
Photosynthesis: Dark Reactions
Now load the CyberEd Biology Course Title: Photosynthesis
View scenes 18 – 21 and complete the exercises below.
You will learn the process of the Calvin Cycle (Dark Reactions).
Multimedia
Presentation
Page 10
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Scene 19
1. Describe the path carbon dioxide typically takes from the atmosphere into the chloroplast where it will
be used in the dark reactions.
Atmosphere  enters leaf via stomata  enters mesophyll cells  enters the stroma
Scene 20 - 21
2. What is the product of the Calvin cycle?
Glucose or other organic molecules (sugars)
3. What is a C3 plant?
A plant that immediately converts carbon dioxide in leaves to the three carbon PGA.
4. Use the diagram to answer questions about the Calvin Cycle in the following table.
How many carbon atoms enter the Calvin cycle as CO 2?
How many carbon atoms are in one molecule of PGA?
How many carbon atoms are in one molecule of PGAL?
3
3
3
How many carbon atoms are in a molecule of glucose?
How many cycles must the Calvin cycle go through to produce one molecule of glucose?
6
2
5. Answer the following questions about the origin and fate of molecules during photosynthesis.
5a) Which molecule donates the carbon to glucose (C6H12O6)?
5b) Which molecule donates the oxygen to glucose (C6H12O6)?
5c) Which molecule donates the oxygen to molecular oxygen (O 2)?
Light Independent Reactions (Dark Reactions)
Now load the MSS Intermediate Biology Simulation: Photosynthesis
View section C: screens #1 – 6.
Computer
Simulation
Page 11
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Dark Reactions
Now load the CyberEd Biology Course Title: Photosynthesis
Complete Interactive Lessons #2 and 6.
Interactive
Lesson
A review of the light and dark reactions, and the path of carbon
molecules.
Quiz: The Dark Reactions
Please take the quiz provided by your teacher.
Quiz
Note from
the teacher
Although the Calvin cycle ultimately leads to the production of
glucose, in a single cycle only one molecule of the 3-carbon PGAL is
produced for 3 CO2 molecules entering the cycle. It takes two
complete turns of the Calvin cycle to convert the two newly produced
3-carbon PGALs to a single 6-carbon glucose molecule.
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© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Photosynthesis Alternatives
Photosynthesis: Alternatives
Now load the CyberEd Biology Course Title: Photosynthesis
View scenes 22 – 27 and complete the exercises below.
Multimedia
Presentation
You will examine photorespiration, and pathways that plants use to
avoid photorespiration.
Scene 22
1. What is photorespiration? What is the importance of the amount of oxygen versus carbon dioxide in
the leaf?
Photorespiration can occur during the Calvin cycle where oxygen is combined with RuBP instead of
carbon dioxide., thus no ATP or glucose is produced. If the air within the leaf is higher in oxygen than
carbon dioxide, the oxygen will out-compete carbon dioxide for attachment to the RuBP molecule.
Scene 23 – 24
2. Use this diagram of a C4 plant’s leaf cells to answer the following questions.
In which cell do C4 plants acquire CO2 initially?
Mesophyll cell
Acquired CO2 combines with PEP to form oxaloacetic
acid. How many carbons are in this molecule?
4
In which cell does the Calvin cycle take place?
Bundle Sheath cell
How does this process avoid photorespiration?
C4 plants acquire CO2 in the mesophyll cell
(which lacks rubisco) by binding with the PEP
molecule (phosphoenolypyruvic acid). The
new 4-carbon compound is oxaloacetic acid,
which is converted to malic acid and shipped
to the bundle sheath cell for conversion to
glucose in the Calvin cycle. This process
acquires CO2 and moves it to a secured cell
for further processing.
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© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Scene 25
3. Check one column per process that occurs in CAM plants.
Day
Stomata open
Calvin cycle
Light reactions
Glucose produced
Rubisco acquires CO2
CO2 is stored
ATP and NADPH is generated
Dark reactions
Night








4. What type plants tend to be CAM plants? In what kind of environment are you likely to find these
plants?
Succulents, like cacti or other desert plants. Hot, dry climates.
Scene 26
5. Where is CO2 kept after the plant has acquired and converted it into a 4-carbon storage molecule? In
what cell does this structure exist?
Vacuole, mesophyll cell
Scene 27
6. Fill in the summary table on C3, C4, and CAM plants.
C3
C4
CAM
In which cell is rubisco found?
Mesophyll
cell
Bundle
Sheath
Cell
Mesophyll
cell
Is photorespiration an issue that the plant must
actively work against?
Yes
No
No
When does CO2 enter the leaves? (Day or Night)
Day
Day
Night
When does the Calvin Cycle occur?
Anytime
Anytime
Day
In which cell does the Calvin Cycle occur?
Mesophyll
Bundle
sheath
cells
Mesophyll
cells
What is the initial carbon molecule that CO2 will
bind to?
RuBP
PEP
How many carbons are in the compound formed
after CO2 is bound to the initial carbon molecule?
3
4
N/A
4
7. If photorespiration didn’t occur, is it likely there would be C4 or CAM plants? Why or why not?
CAM plants likely, because CAM offers an alternative to water loss in hot, dry environments.
Page 14
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Review of C3, C4, and CAM plants
Now load the CyberEd Biology Course Title: Photosynthesis
Complete Interactive Lesson # 7.
Interactive
Lesson
Review how different plants can avoid photorespiration through
different pathways.
Page 15
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
Photosynthetic Products
Products of Photosynthesis
Now load the CyberEd Biology Course Title: Photosynthesis
View scenes 28 – 31 and complete the exercises below.
Multimedia
Presentation
Learn the benefits of glucose production for plants, and the impact of
photosynthesis on the global climate.
Scene 28
1. Name three ways that a plant can use glucose.
a) Glucose contains energy within the bonds to generate ATP for cellular functions
b) Glucose can be modified to form building materials, e.g., cellulose
c) Glucose can be stored as starch for later use.
Scene 29
2. This graph displays local atmospheric CO2 measurements taken over several years at Mauna Loa,
Hawaii. The graph is approximately divided by seasons: Fall/Winter and Spring/Summer. Use the graph
to answer the questions pertaining to photosynthetic rates by season.
a) When is CO2 use by plants the
highest?
Spring/Summer
b) When is the rate of
photosynthesis the highest?
Spring/Summer
c) When is glucose production the
highest?
Spring/Summer
d) When is oxygen production the
highest?
Spring/Summer
Scene 30 - 31
3. What is one possible cause of the increase in global temperatures?
Increase in CO2, due to industrialization, burning substances such as wood, oil, gas, coal
4. What is the Greenhouse Effect?
The greenhouse effect is due to presence of gases, such as CO 2, in the atmosphere that trap heat from
the sun, prevent it from radiating back out to space, and increase the overall temperature of the planet
5. How can photosynthetic organisms counteract the build up of CO 2 in the atmosphere?
Photosynthetic organisms can act as CO2 reservoirs, pulling CO2 out of the atmosphere, converting it to
glucose and other carbon storage molecules, and holding onto to the carbon for an extended period of
time.
Page 16
© 2003 Cyber Ed, Inc.
CyberEd® Student Study Guide: Photosynthesis
6. A wildfire spreads to a large forest of long-living pine trees. What immediately happens to CO 2 in the
atmosphere in that region?
Lots of CO2 will be released when the plants burn increasing the amount of CO 2 in the atmosphere locally
for a brief period.
7. An oil spill in the ocean darkens the water. What impact does this have on photosynthetic organisms
living in those waters? What is the effect on CO2 in the area?
The photosynthetic organisms can’t undergo photosynthesis without light so no CO2 will be taken up.
Levels of CO2 in the environment
Now load the CyberEd Biology Course Title: Photosynthesis
Complete Interactive Lesson # 8.
Interactive
Lesson
Review how photosynthesis influences carbon dioxide levels in the
environment.
Quiz: ATP Generation
Please take the quiz provided by your teacher.
Quiz
Comprehensive Exam: Photosynthesis
Please take the exam provided by your teacher.
Test
Page 17
© 2003 Cyber Ed, Inc.