Photosynthesis is a two-stage process by which plants use sunlight, carbon dioxide, and water to produce oxygen and sugars like glucose. In the light reactions, chlorophyll in plant leaves absorbs sunlight to provide energy to convert carbon dioxide and water into oxygen and energy carriers like ATP. In the dark reactions, the energy carriers are used to produce sugars from carbon dioxide. Photosynthesis is essential for plants to survive and produces oxygen for other living things to survive.

1. PHOTOSYNTHESIS
Victoria Johnson
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2. What is photosynthesis?
• The process by which plants and some bacteria use the
energy from sunlight to produce sugar, which then cellular
respiration converts into ATP, the "fuel" used by all living
things.
• 6H2O + 6CO2 ----------> C6H12O6+ 6O2
• The conversion of unusable sunlight energy into usable
chemical energy, is associated with the actions of the green
pigment chlorophyll. Most of the time, the photosynthetic
process uses water and releases the oxygen that we
absolutely must have to stay alive. (Wiley&).

3. Leaves and their structure:
• The raw materials of photosynthesis, water and carbon dioxide, enter the
cells of the leaf, and the products of photosynthesis, sugar and oxygen,
leave the leaf.(PhotoBritannica)
• important to the study of photosynthesis: stoma, guard cell, mesophyll
cells, and vein. google.images.com

4. • Water enters the root and is transported up to the leaves
through specialized plant cells known as xylem. Land plants
must guard against drying out and so have evolved
specialized structures known as stomata to allow gas to
enter and leave the leaf. Carbon dioxide cannot pass
through the protective waxy layer covering the leaf
(cuticle), but it can enter the leaf through an opening
flanked by two guard cells. Which is something we have all
seen many times in biology lab. Likewise, oxygen produced
during photosynthesis can only pass out of the leaf through
the opened stomata (Photo columbia).
C02 enters through the guard cells
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5. Chlorophyll:
Thecockeyedregister.com Google.images.com

6. • A pigment is any substance that absorbs light.
The color of the pigment comes from the
wavelengths of light reflected (in other
words, the ones not absorbed)
(Cronquist, Arthur).
• Black pigments absorb all of the wavelengths that
strike them. White pigments/lighter colors reflect
all or almost all of the energy striking
them, (Cronquist, Arthur).
• Chlorophyll, the green pigment common to all
photosynthetic cells, absorbs all wavelengths of
light except green, which is why it reflects green
in our eyes, (Cronquist, Arthur).

7. Other pigments
• Chlorophyll is a complex molecule.
• All photosynthetic organisms contain
chlorophyll a.
San Luis

8. • Accessory pigments include chlorophyll b
(c, d, and e in algae and
protistans), xanthophylls, and carotenoids
(such as beta-carotene).
(Bonner, James)
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9. Stages of photosynthesis:
• Photosynthesis is a two stage process.
• The Light Reactions occur in the grana and the
Dark Reactions take place in the stroma of the
chloroplasts, (Gasexchange).
Wikipedia.com

10. Light reaction:
• light strikes chlorophyll a in such a way as to
excite electrons to a higher energy state. In a
series of reactions the energy is converted into
ATP and NADPH. Water is split in the process,
releasing oxygen as a by-product of the reaction.
The ATP and NADPH are used to make C-C bonds
in the other process, dark reaction, (Bonner,
James).
• The first process is the Light Dependent Process
(light reaction), requires the direct energy of light
to make energy carrier molecules that are used in
the second process, (Bonner, James).

11. Dark reaction
• Dark reactions occurs when the products of
the Light Reaction are used to form C-C
covalent bonds of carbohydrates. The Dark
Reactions can usually occur in the dark, if the
energy carriers from the light process are
present.

12. How does any of this happen?
• “This occurs when the electrons from water are excited by the
light in the presence of P680, (Gasexchange).
• “ Light energy causes the removal of an electron from a
molecule of P680. The P680 requires an electron, which is
taken from a water molecule, breaking the water into H+ ions
and O-2 ions. These O-2 ions combine to form the diatomic O2
that is released” (Solarenergy).

13. • The electron is then "boosted" to a higher
energy state and attached to a primary
electron acceptor, which begins a series of
redox reactions, passing the electron through
a series of electron carriers
Put domino picture here

14. • The electron is then passed again through a
series of redox reactions, eventually being
attached to NADP+ and H+ to form NADPH, an
energy carrier needed in the dark reaction.
• The electron from Photosystem II replaces the
excited electron in the P700 molecule. There is
thus a continuous flow of electrons from
water to NADPH… This energy is used in
Carbon Fixation.
(Solarenergy)

15. summary
• Sunlight
• Produce sugar
• Two stage process-dependency
• Sugar converts to ATP
• ATP= “fuel” for all living things
• Sunlight turned into chemical energy
• chlorophyll

16. Benefits: Plants
• Photosynthesis is the process by which plants
use energy from the sun (along with carbon
dioxide and water) to create its own food.
Without photosynthesis, plants would die.
Bettysoriginalembroideries.com

17. • “Photosynthesis is responsible for the
conversion of carbon from carbon dioxide
into organic compounds in plants. It allows
the plant to make organic building blocks,
new cells, starch, and proteins. Without this
process, life as we know it would not exist on
earth. Plants provide, directly or indirectly,
food for all animals and all of our
atmospheric oxygen” (San Luis).

18. Benefits: Earth and its people
• Photosynthesis is the process by which plants
make their own food. Plants use sunlight and
light energy to make their own food in order
to survive; without photosynthesis, there
would be no plants, and without plants there
would be no oxygen and therefore the world
could not survive either.
123RF.com

19. WORK CITED
• Wiley and Sons, Inc, John. "Interactive Concepts in Biochemistry - Photosynthesis." Wiley: Home.
2002. Web. 04 Oct. 2011.
<http://www.wiley.com/legacy/college/boyer/0470003790/animations/animations.htm>.
• "Photosynthesis." The Columbia Encyclopedia. New York: Columbia UP, 2008. Credo Reference. 7
Nov. 2008. Web. 7 Oct. 2011. <http://www.credoreference.com/entry/columency/photosynthesis>.
• "Photosynthesis." Dictionary of Microbiology & Molecular Biology. Hoboken: Wiley, 2006. Credo
Reference. 18 Mar. 2010. Web. 7 Oct. 2011.
<http://www.credoreference.com/entry/wileymicrob/photosynthesis>.
• "Photosynthesis." Britannica Concise Encyclopedia. Chicago: Encyclopaedia Britannica, 2009. Credo
Reference. 3 Sept. 2010. Web. 7 Oct. 2011.
<http://www.credoreference.com/entry/ebconcise/photosynthesis>.
• "Gas Exchange." The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide. Abington:
Helicon, 2010. Credo Reference. 4 Jan. 2011. Web. 7 Oct. 2011.
<http://www.credoreference.com/entry/heliconhe/gas_exchange>.
• Bonner, James. "Chlorophyll." Encyclopedia Americana. Grolier Online, 2011. Web. 7 Oct. 2011.
• Cronquist, Arthur. "Leaf." Encyclopedia Americana. Grolier Online, 2011. Web. 7 Oct. 2011.
• Bassham, James A. "Calvin, Melvin (1911–1997)." Encyclopedia Americana. Grolier Online, 2011.
Web. 7 Oct. 2011.
• "Solar Energy." Encyclopedia Americana. Grolier Online, 2011. Web. 7 Oct. 2011.
• Sinnott, Edmund W. "Botany." Encyclopedia Americana. Grolier Online, 2011. Web. 7 Oct. 2011.

20. Pictures..
• 123RF.com
• Betty’s original embroideries
• Thecockeyedregister.com
• google.images.com
• SanLuisObispo
• wikipedia