Biology 9
Unit 7 :Photosynthesis
Created by: Jeff Wolf and Mike Graff
Objectives: After completing this
Learning Quest the student will…
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Compare the differences
between autotrophs and
heterotrophs.
Describe the basic
processes of
photosynthesis.
Describe how light
influences the light
reactions.
Describe the importance
of the Calvin Cycle.
Directions
1.
2.
3.
4.
Follow the instructions in
the Anticipation Guide
found in this PowerPoint
Presentation.
Follow the instructions
and answer all questions
found in the Learning
Guide.
Follow the instructions in
the Conclusion Guide.
ALL THREE GUIDES
CAN BE FOUND IN THIS
LEARNING
POWERPOINT QUEST.
Anticipation Guide (Page 1)
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During the
Anticipation Guide
we will focus on the
dependence on plants
for much of our
nutrition and energy.
Plants are said to be
autotrophs which
means “self-feeders”.
Anticipation Guide (Page 2)
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Autotrophs use inorganic
material: carbon dioxide from
the air, and minerals and water
from the soil to make their own
organic materials, including
carbohydrates, lipids, proteins,
and nucleic acids.
On the other hand,
heterotrophs, meaning “other
feeders”, cannot make organic
materials from inorganic
materials. That is why we
must eat fruits, vegetables,
meats, and grains.
Anticipation Guide (Page 3)
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Heterotrophs depend on
autotrophs for nutrients.
Autotrophs depend on a
process called
photosynthesis for
nutrition.
We will examine the
process of photosynthesis
in the following Learning
Guide slides.
Learning Guide (Page 1)
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Photosynthesis is the
process in which light
energy is used to create
organic material.
Photosynthesis cannot
occur without the help of
chloroplasts.
Chloroplasts are disc
shaped organelles found
in certain plant cells that
carry out the process of
photosynthesis.
Learning Guide (Page 2)
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Chloroplasts are located
within the mesophyll of the
leaf. The mesophyll, is the
green tissue found inside the
interior of the leaf.
Also an important part to the
photosynthetic processes are
tiny pores located on the leaf
surface called stomata.
The stomata allow carbon
dioxide to enter the leaf and
allows oxygen to exit the
leaf.
Learning Guide (Page 3)
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Found throughout the leaves and
body of the plant are vital
components called xylem and
phloem.
Xylem consists of dead cells
designed for transporting water
and minerals from roots to
leaves.
Phloem cells consist of living
cells that distribute sugars from
the leaves to roots and other
parts of the plant that are not
photosynthetic.
Learning Guide (Page 4)
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Another important
component of the
photosynthesis process
is the ability of plants to
receive water through
precipitation.
As seen in the diagram
to the right, the water
cycle plays a vital role
in delivering a vital
resource to all plants.
Learning Guide (Page 5)
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The chemical equation below provides a look at
the reactants and products of photosynthesis. You
will notice that the reactants of photosynthesis,
carbon dioxide and water, are also the waste
products of cellular respiration.
Learning Guide (Page 6)
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Photosynthesis is a very
complex process.
The process of
photosynthesis has two
stages. The two stages
include the Light
Reactions and the Dark
Reactions/Calvin Cycle.
Refer to pages 102 –115.
Learning Guide (Page 7)
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Sunlight, a type of energy
produces an assortment of
wavelengths. The full
range of the electromagnetic spectrum is
shown to the right. Note:
plants only use the band of
energy referred to as visible
light.
Visible light, is only a small
portion of this spectrum. It
consists of those
wavelengths that our eyes
see as different colors.
Electromagnetic Spectrum
Learning Guide (Page 8)
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In the first step called the Light
Reaction, sunlight shines on
pigmented materials called
chlorophyll a and chlorophyll b
found within the chloroplasts.
Chlorophyll a - absorbs the blueviolet and red wavelengths
produced by sunlight.
Whereas, Chlorophyll b primarily
absorbs the blue and orange wave
lengths and reflects the yellowgreen wavelengths. This is the
reason why most plants are green
in color.
Learning Guide (Page 9)
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When a pigment
molecule, like
that of
chlorophyll,
gains energy, it
will not only
absorb this
energy it will
also emit light
and heat.
Learning Guide (Page 10)
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The light reaction
generates ATP,
oxygen and
hydrogen by
splitting water.
This step creates
the necessary
energy and
hydrogen that is
required for the
second step of
photosynthesis.
Learning Guide (Page 11)
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Energized electrons
from the watersplitting photosystem
pass down an electron
transport chain to the
NADPH-producing
photosystem (2) .
The chloroplast uses
the energy released
by this electron “fall”
to make ATP.
Learning Guide (Page 12)
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* Light reaction process taken from
Campbell and Reece’s Essential Biology
textbook. 2001
The NADPHproducing
photosystem transfers
its photo-excited
electrons to NADP ,
reducing it to NADPH
(3) .
The electron transport
chain replaces the
electrons lost from the
photosystem’s
chlorophyll.*
Learning Guide (Page 13)
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Plants then make
sugar molecules
during the second
stage of
photosynthesis
using carbon
dioxide during a
process known as
the Calvin cycle
or the Dark
Reaction.
Learning Guide (Page 14)
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In the first step of the
Calvin cycle, Carbon
atoms (three gray
CO2 balls enter the
cycles (1) .
An enzyme adds the
CO2 to RuBP (a
ribulose bisposphate, a
five-carbon sugar
already present in
chloroplast. The
product created is now
called 3PGA or 3phosphoglyceric acid)
Learning Guide (Page 15)
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In step two of the
Calvin cycle, ATP
and NADPH from the
light reactions
provide energy and
electrons (2) .
Enzymes use the ATP
energy and highenergy electrons from
NADPH to convert
the 3-PGA to threecarbon sugar, G3P
(glyceraldehyde-3phosphate).
Learning Guide (Page 16)
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In step three of the
Calvin cycle, Carbon
exits the cycle as sugar
(Glucose) (3) .
Therefore, three CO2
molecules have been
converted to one
molecule of sugar G3P.
This is the direct product
of photosynthesis but
plant cells can use the
G3P to make glucose
and other organic
compounds for growth
and fuel.
Learning Guide (Page 17)
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In the fourth and final step
of the Calvin cycle, the
cycle regenerates its starting
material. Note that of the
six G3P molecules produced
in step 3 only one of them
represents net sugar output
(4) . That’s because we
started with a total of 15
sugar carbons in the three
RuBP molecules that
accepted CO2 back in step
one.
Enzymes now regenerate the
RuBP by rear-ranging the
five G3P molecules that are
left after one of those sugars
exits the cycle.*
*Explanation
of Calvin cycle
taken from
Campbell and
Reece’s
Essential
Biology
textbook. 2001
Learning Guide (Page 18)
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Throughout the evolution of plants natural
selection has forced plants to adapt their
photosynthesis capabilities.
Plants that use CO2 directly from the air are
called C3 plants because the first organic
compound produced, by these plants, is a
three-carbon compound called 3-PGA.
Learning Guide (Page 19)
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Another type of plant,
a C4 plant has special
adaptations that save
water without shutting
down the process of
photosynthesis.
These C4 plants keep
their stomata/pores
closed during the
daytime to conserve
water, yet at the same
time continue to make
sugar.
Examples of these
plants include -
Learning Guide (Page 20)
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Cacti, ice plants, and jade
plants are classified as
CAM plants.
CAM plants conserve
water by opening its
stomata and taking in
CO2 at night.
The CO2 is released
during the day through
the Calvin cycle.
Pineapple plant
Works Cited
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http://www.chagres.com/ae-rainforest-1.jpg
http://pantransit.reptiles.org/images/1996-07-28/washington-rain-forest.png
http://www.free-desktop.net/wallpapers/wa/tall-forest.jpg
http://wuarchive.wustl.edu/aminet/pix/views/forest.jpg
http://www.bio.umass.edu/biology/conn.river/plant_images/forest2.jpg
After completing the test, move onto Unit #8.