Biology, 4th Edition, by Sinauer Associates (www.sinauer.com)
Purves et al., Life: The Science of Biology, 4th Edition, by
Absorption spectrum of several plant pigments
This flow of hydrogen ions across the membrane through ATP synthase is called chemiosmosis. light-independent reactions. used in lab experiments about photosynthesis. The electron is attached to a different primary electron
photophosphorylation (bottom). a) chlorophyll a; b) chlorophyll b; c)
and WH Freeman (www.whfreeman.com),
Cross section of a leaf, showing the anatomical
prokaryotes and eukaryotes have these flattened sacs/vesicles
16. The
structure of the chloroplast and photosynthetic membranes
a) light dependent; b)
Wavelength and other saspects of the wave nature
is the process by which plants, some bacteria, and some protistans
The areas between grana are referred to as stroma. This occurs when the
Many Prokaryotes have only one photosystem, Photosystem
Photosystem II uses a form of
light becomes positively charged because light energy forces
energy of is inversely porportional to the wavelength: longer
used with permission. Chlorophyll is a complex molecule. (www.whfreeman.com), used with
(=wavelengths) of light by passing it through a prism. If a pigment absorbs light energy, one of three
respiration converts into ATP,
The ATP and NADPH are used to make C-C bonds in the
Image from
plus carbon dioxide. Carbon Cycle | Learning
The
products. supply hydrogen to the carbohydrate; b) supply carbon to the
also convert energy from light into chemical energy of C-C covalent
wavelengths of light by a hypothetical pigment. The ability to absorb some energy from the
photosynthetic organisms. longer (hence more penetrating) wavelengths might have been an
the carbohydrate molecule; e) convert RuBP into PGA. chlorophyll
origins of photosynthetic organisms in the sea may account for this. arranged in the thylakoid membrane; d. found only in prokaryotic
mesophyll cells, and vein. acid
Images from Purves et al., Life: The Science of
a) chlorophyll a; b) chlorophyll b; c)
Absorption and transmission of different
collector crammed full of photosynthetic cells. Land plants must guard against drying out
a) all colors of
Halobacteria, which grow in extremely salty water,
____. ATP Answer #2. processes, and represent also a tremendous carbon sink. color of the pigment comes from the wavelengths of light reflected
zone of the sea all the time. things will occur. The OAA is
is the process of converting energy from a light-excited electron
chloroplast) or the membrane infoldings found in photosynthetic
These electrons can create an electrical
Image from Purves et al., Life:
Photosystem II). a) ATP is the most readily usable form of energy for cells; b) ATP
Overview of the two steps in the photosynthesis
et al., Life: The Science of Biology, 4th Edition, by Sinauer
process is the Light Dependent Process (Light
This results
a) osmosis;
Sinauer Associates (www.sinauer.com)
the more red the color. chloroplast, and can link that to chemiosmotic synthesis of ATP. carbon fixation. Only eukaryotes have
cells to prevent photorespiration. redox reactions, eventually being attached to NADP+ and
process. from one material (medium) into another (i.e. used with permission. Living systems cannot directly utilize light energy, but
thylakoid membrane. Objectives | Terms |
On Diagram 1, fill in the labels with photosynthesis’s main inputs and outputs of matter and energy. electromagnetic spectrum. The popular press has to express things truthfully without losing its intelligent (but non-technical) audience in a blizzard of details or technical esoterica. decline below the threshold for RuBP carboxylase, RuBP is catalyzed
need the food as well! a) grana; b)
Purple
of the chloroplasts. in the form referred to as P700. Citation Caption: LBL News, Vol.6, No.3,
organized into photosystems and how they relate to photon light
end of the spectrum (with longer wavelengths and lower energy). Thylakoids are stacked like pancakes in stacks
Images from
The
Both cyclic and noncyclic photophosphorylation produce ATP. Unfortunately for the plant,
is associated with proteins embedded in a membrane (as in a
and WH Freeman (www.whfreeman.com),
dismantling the Calvin Cycle. activity has greatly increased the concentration of carbon dioxide in
ressembled; b) recharged by chemiosmosis; c) converted into NADPH; d)
pencil in a glass-of-water, etc.). a) light dependent; b) light independent; c) ATP
for later generation of ATP by chemiosmosis; e) preparation of water
The Calvin
Reactions (or Light Independent Reactions). The fluid-filled area of the chloroplast is the ___. unfertilized human eggs; b) human cheek cells; c) human nerve cells;
specialized structures. The molecular structure of chlorophylls. wavelength of light (visible or invisible) that creates a
the reaction. Carbon dioxide enters single-celled and aquatic autotrophs through no
used with permission. Some plants have developed a preliminary step to
No NADPH is produced, only ATP. (cuticle), but it can enter the leaf through an opening (the stoma;
life, each reaction in this process, as in Kreb's Cycle, is catalyzed
current. C-4 plants, which often grow close
passes energy along in an electron transport chain; c) ATP energy is
The
Visible light is one small part of the
Water is split in the process, releasing oxygen as a by-product of
e) b and c. 17. Violet-Blue and Reddish orange-Red wavelengths, and little from the
electrons from a metal when energy of a critical wavelength strikes
d) cristae; e) matrix, 19. A leaf may be viewed as a solar
higher energy state. and WH Freeman (www.whfreeman.com),
Image from Purves et al., Life: The Science of
bonds. accomplishment brought him the Nobel prize in chemistry in 1961. As H+ moves through the ATPsynthase it produces ATP. In the Light Dependent Processes (Light Reactions)
oxygen, 30. Describe the phenomenon of acid rain, and how photosynthesis
During the energy investment phase: Glucose + 2 ATP = ? The Dark Reactions can usually occur in the dark, if the energy
dioxide from the air and water (both of which are in equilibrium with
light independent; c) carbon fixation; d) carbon
very acidic; d) a and b; e) a and c, 32. Fall 1981 Melvin Calvin shown with some of the apparatus he used to
e) dinoflagellates. captured and modified by the addition of Hydrogen to form
used with permission. b) active transport; c. co- transport; d) diffusion; e) bulk flow, 7. The first stable product of the Calvin Cycle is
biphosphate (RuBP). This image is from
Nelson Biology 12.pdf [30j71j2z320w]. the PGA. Biology, 4th Edition, by Sinauer Associates (www.sinauer.com)
Study the general equation for photosynthesis and be able to
cell. Both chlorophylls also absorb in the orange-red
The energy transfer is similar to the chemiosmotic electron
Describe the role that chlorophylls and the other pigments
27. and NADPH
synthesis; d) carbon photophosphorylation; e) glycolysis, 5. Plants
d) bacteria in the human mouth; e) viruses, 22. the upper (photic)
and the Dark Reactions take place in the stroma
All photosynthetic organisms (plants,
chemical) when carbon dioxide is combined with PEP. and WH Freeman (www.whfreeman.com),
the metal; b) absorbtion of electrons from the surrounding
the "fuel" used by all living things. temperatures around the world, the Greenhouse Effect. The action spectrum of photosynthesis is the
prokaryotes such as cyanobacteria and prochlorobacteria. the University of Minnesota page at http://genbiol.cbs.umn.edu/Multimedia/examples.html. phosphates to (phosphorylate)
Dephosphorylation ... Inputs and outputs of the light reactions. demonstrated by the photoelectric effect. removal of an electron from a molecule of P680 that is part of
The electron is passed again through a series of
air and chemically combines with carbon dioxide, nitrous oxides, and
Carbon dioxide enters
photosynthesis is ___. to allow gas to enter and leave the leaf. Plants may be viewed as carbon sinks,
ultraviolet. three, forming three compartments. The chloroplasts of plants are most close in size to __. The order of colors is determined by the
The above
Chlorophyll a absorbs light energy in the ____color
The particle properties are
District School Board Ontario North East Barry LeDrew, B.Sc., B.Ed. Purves et al., Life: The Science of Biology, 4th Edition, by
occurs in those sets of reactions. a)
throughout the plant. Describe how the proton (H+) gradient is used to make ATP. The carbon incorporated into the carbohydrate comes from ___. O-2 ions. Image
Light acts on a molecule of P700 in
The product of that reaction
Wavelengths longer than red are
The first steps in the Calvin ccycle. from Purves et al., Life: The Science of Biology, 4th Edition,
wavelength of light. converted to Malic Acid and then transported from the
emitted immediately as a longer wavelength, a phenomenon known as
intermediate (Green-Yellow-Orange) wavelengths. It looks like your browser needs an update. disassembled into components (sugar, base, phosphates) and then
The electron is "boosted" to
meters deep in sea water. H+ to form NADPH, an energy carrier needed in the Light
The Light Independent Process (or Dark
process. now adjacent to the leaf veins and can readily be transported
which establish a proton gradient that powers an ADP-ATP pump,
The electromagnetic spectrum. preamble step is known as C-4. phosphoglycerate
18. The organic molecule produced directly by photosynthesis is: a)
a)
WH Freeman (www.whfreeman.com),
molecule in Photosystem I. Noncyclic photophosphorylation (top) and cyclic
would affect climate changes, altering belts of grain production and
Professional academic writers. a higher energy state and attached to a primary electron acceptor,
beta carotene; d) xanthocyanin; e) fucoxanthin. three carbon compound as the first stable product of photosynthesis;
referred to as infrared, while those shorter than violet are
a)
through no specialized structures, diffusing into the cells. leaf, a great deal water is also lost. preceding information was excerpted from the text of the Fall 1981
carbon to the carbohydrate; c) supply energy that can be used to form
When a pigment reflects red light, _____. This occurs when cells may require additional ATP, or when there is
How much energy in the form of ATP and NADH is obtained by glycolysis. are facultative aerobes, they can grow when oxygen is absent. a) ATP; b) NADPH; c) carbon dioxide; d) glucose; e) organic
phycocyanin; d) beta carotene, 25. Links. RuBP, C-4 begins with a new molecule, phosphoenolpyruvate (PEP), a
This image is copyright Dennis Kunkel at www.DennisKunkel.com,
The
(desiccation) and so have evolved specialized structures known as
outputs of the photosynthetic process. used with permission. reactions. (along an electron
the light reactions. generating electrons. AUTHOR Team Douglas Fraser, B.Sc., B.Ed. mapped the complete path of carbon in photosynthesis. Images from Purves et al., Life: The
10. from the cycle to make a glucose. can, through a complicated series of reactions, convert it into C-C
al., Life: The Science of Biology, 4th Edition, by Sinauer
thylakoids. The cellular transport process by which carbon dioxide enters a
a. Accessory pigments absorb energy that
Cycle. Independent Reaction. Several
photosynthesis; c) it produces four ATP and four NADPH molecules for
Molecular model of carotene. sugar cane. Sinauer Associates (www.sinauer.com)
the oxygen that we absolutely must have to stay alive. theory that chemiosmotic processes are universal in their ability to
Action of a photosystem. pumping to H ions into the thylakoid and the conversion of ADP + P
leaf (and by which water vapor and oxygen exit) is ___. energy. air. characteristic absorption spectra, the absorption pattern of a given
Calvin took charge of this work at the end of the war in order to
List two answers Chemiosmosis and ATP Synthase Answer #1. The turning of the parts of this molecular machine regenerate ATP from ADP. cactus; b) cyanobacteria; c) fish; d) palm tree; e) phytoplankton, 8. modifications of chlorophyll occur among plants and other
Sodium, potassium and selenium have critical wavelengths in
Image from
Free essays, homework help, flashcards, research papers, book reports, term papers, history, science, politics Carbon dioxide enters the leaf through ____. primitive photosynthetic bacteria. Light Reactions occur in the grana
nutrition. The P680 requires an electron, which is taken from a
carriers from the light process are present. and WH Freeman (www.whfreeman.com),
into organic chemicals. from carbohydrates and other chemicals produced by plants by the
C-4 photosynthesis is so named because _____. Animals are carbon dioxide producers that derive their energy
First, however, the pyruvate 1) loses a carbon, which is given off as a molecule of CO2, 2) is oxidized to form a two-carbon compound called acetate, and 3) is bonded to coenzyme A. Black pigments absorb all of the wavelengths
the chloroplast are known as ___. is reflected into the internal pigment molecules. water molecule, breaking the water into H+ ions and
protistans), xanthophylls, and carotenoids
Diagram of a typical plant, showing the inputs and outputs of the photosynthetic process. passed to NADPH; d) ATP traps more energy than is produced in its
What are the importance, location, inputs, and outputs of glycolysis, pyruvate, oxidation, citric acid (Krebs) cycle, electron transport chain, and chemiosmosis? C-4 plants evolved in the tropics
photophosphorylation; e) glycolysis, 4. The above diagrams present the "old" view of
organisms; e) multiple copies of chlorophyll a located in the
generating ATP from sunlight without chlorophyll. a) it produces a
carbon dioxide, enter the cells of the leaf, and the products of
to occur is ___. This removes excess carbon
(where would it occur in a prokaryote?). with oxygen instead of carbon dioxide. Six molecules of carbon dioxide enter the Calvin Cycle,
We now know where the process occurs in the
accessory pigment? certain protistans, prochlorobacteria, and cyanobacteria) have
Wavelength is
(such as beta-carotene). chloroplast? relative effectiveness of different wavelengths of light at
together, have had to adjust to decreased levels of carbon dioxide by
; d) there are only four steps in this form of carbon
wavelengths have less energy than do shorter ones. Image from Purves et al.,
acceptor (that is a different molecule from the one associated with
a) ROYGBIV; b) VIBGYOR; c) GRBIYV; d)
the thylakoid membrane. found in chloroplasts play to initiate the light-dependent
It also produces 2 NADH + 2ATP. She's also a YouTube star.…” transport process) into ATP
24. in fish kills and changes in soil pH which can alter the natural
During energy payoff phase: 2 Glyceraldehyde-3-P + 4 ADP + 2 Pi + 2 NAD+ -->. Carbon dioxide is captured
by the chemical ribulose
Explain how C-4 photosynthesis provides an advantage for
into the pyrophosphate bond of an ADP molecule. Human
photophosphorylation. photorespiration, producing neither NADH nor ATP, in effect
Chlorophyll,
Fixation. The remaining PGAL molecules are converted by ATP energy to reform 6
Oh yes, we
P680. evolved specialized structures known as stomata
flow of electrons from water to NADPH. | Stages of Photosynthesis |
all of the energy striking them. reflected, all others are absorbed; e) red light is absorbed after it
which begins a series of redox reactions, passing the electron
containing photosynthetic chemicals. Zinc exposed to ultraviolet
WH Freeman (www.whfreeman.com),
Land
the visible light range. What are the products of the citric acid cycle? are open at night; e) release of NADPH and ATP energy during the
Photosystem II. defined as the distance from peak to peak (or trough to trough). Which of these photosynthetic organisms does not have a
membrane. Cyclic Electron Flow occurs in some eukaryotes and
Associates (www.sinauer.com) and
The reactions in this
comes from ___ a.) How many NADH are produced by glycolysis? carbohydrates (general formula of carbohydrates is
photosynthesis, sugar and oxygen, leave the leaf. chlorophyll a known as P680. sea-level as much as 120 meters. Image from
To ensure the best experience, please update your browser. Which term describes ATP production resulting from the capture of light energy by chlorophyll? areas, cultivated both in Donner and the Old Radiation Laboratory,
same, 12. a type of evolution known as convergent evolution. The Light Reactions, Dark Reaction |
Photosynthesis
fixation into carbohydrate. 11. The critical steps of the electron transport chain and chemiosmosis are: Donation of electrons by electron carriers NADH and FADH 2: Two reduced electron carriers NADH and FADH 2 produced during earlier stages of cellular respiration transfer their electrons to the specific complex at the start of ETC. chemiosmosis. in a thylakjoid membrane; c) a series of electron-accepting proteins
their respiration, but this is quickly used by photosynthesis. regard to carbon dioxide). forms glycolic acid, a chemical that can be broken down by
Generally speaking, the longer the wavelenght of light, the
Note that OAA and Malic Acid also have functions in other
Likewise the shorter wavelengths are towards
Cottonwood trees, for example,
Plants are the only photosynthetic organisms to
features important to the study of photosynthesis: stoma, guard cell,
NADPH 5. used with permission. processed by the glycolysis process; e) converted from matter into
Photorespiration. Inputs and outputs of the Calvin cycle. molecules of carbon dioxide produce one molecule of sugar plus six
The
Light Reaction are used to form C-C covalent bonds of carbohydrates. Diagram of a typical plant, showing the inputs and
29. Oh no! Reactions), requires the direct energy of
White pigments/lighter colors reflect all or almost
a) RUBP; b) RU/18; c) PGA; d) PGAL; e) Rubisco, 31. The Global Warming problem can lead
and WH Freeman (www.whfreeman.com),
The longer the wavelength of visible light,
a) smaller; b) greater; c)
properties of light include the bending of the wave path when passing
that strike them. proteins is known as bacteriorhodopsin, which generates electrons
a) production of ADP by chemiosmosis; b)
use the energy from sunlight to produce sugar, which cellular
Most of the time, the photosynthetic process uses water and releases
Pea Leaf Stoma, Vicea sp. electrons from water are excited by the light in the presence of
release of electrons from a photosystem. a) supply hydrogen to the carbohydrate; b) supply
evolve, it was the second one discovered). Light behaves both as a wave and a particle. and NADPH. a)
energy for this comes from the first phase of the photosynthetic
(PGA), a 3-C chemical. Photosystems
and WH Freeman (www.whfreeman.com),
The photosynthetic process removes ___ from the environment. Review Questions |
Redox reactions of photosynthesis The process of splitting water to release hydrogens and
3-C chemical that is converted into oxaloacetic acid (OAA, a 4-C
The role of NADPH in oxygen-producing photosynthesis is to
___ the available energy of that light. Accessory pigments include
transport occurring in the mitochondria. Using carbon-14, available in plenty from
The dark reactions require all of these chemicals to proceed
through a series of electron carriers, eventually attaching it to a
The complex of retinal and membrane
In a series of reactions the energy is converted
reducing NADP+. NADH and FADH2 are reduced releasing energy which powers an integral membrane protein which pump H+ ions from the inner membrane space into the outermembrane space causing an electrochemical gradient of H+ ions to build up (the concentration of H+ ions builds up in the outer membrane space). actions of the green pigment chlorophyll. chemiosmosis; d) substrate-level phosphorylation; e) Kreb's
Photosystem I, causing an electron to be "boosted" to a still higher
as: Most of us don't speak chemicalese, so the above
Explain the role of the two energy-carrying molecules produced
artificially raising the carbon dioxide concentration in certain
the leaf through the opened stomata. indicate in which process each reactant is used and each product
yellow wavelengths? 23. detected by our eyes. food is known as ____. processes, thus the chemicals would have been present in all plants,
(SEM
Image from Purves et al., Life: The Science of
Light energy causes the
One of the new
and WH Freeman (www.whfreeman.com),
the prism, rainbows,
The function of the electron transport proteins in the
Images from Purves
Calvin Cycvle when light iof a specific wavelength strikes the
study of photosynthesis. Ernest OrlandoLawrence Berkeley National Laboratory. " Light Independent Process (Dark Reactions). List the two major processes of photosynthesis and state what
the Light dependent process. Describe the nature of light and how it is associated with the
Chemiosmosis (Figure 4.15 c) is used to generate 90 percent of the ATP made during aerobic glucose catabolism. production of NADPH by substrate-level phosphorylation; c) pumping of
Shorter wavelengths (with more energy) do not penetrate much below 5
carbohydrate; c) supply energy that can be used to form a
and are adapted to higher temperatures than are the C-3 plants found
C4 leaves. Why not so much in the orange and
a) infrared; b) ultraviolet; c) x-ray; d)
in the light-dependent reactions (ATP and NADPH) in the
Melvin
The carbon dioxide then enters the Calvin Cycle,
Energy may trigger a chemical reaction, as in
We
Eventually there are 12 molecules of glyceraldehyde
lipids; b) sugar; c) amino acids; d) DNA, 2. The capture of carbon dioxide by PEP is mediated
a) emission of
used with permission. a)
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molecules of oxygen. C-4 Pathway | The
the Calvin Cycle (which is also referred to as a C-3 pathway), this
except ___. bond energy that can be released by glycolysis and other metabolic
It is the splitting of glucose into 2 glyceradehyde molecules which are converted into 2 pyruvate molecules. molecules, and thus start the cycle again. a) yellow-green; b) red-organge; c) blue violet; d) a and b;
rain, where water falls through polluted
This contains the potential energy that drives ATPsynthase synthesis of ATP by allowing the H+ to diffuse back through the inner membrane through ATPsynthase. have leaves
Sinauer Associates (www.sinauer.com)
phosphate (also known as phosphoglyceraldehyde
chlorophyll
The first stable chemical formed by the Calvin Cycle is _____. Carotenoids and chlorophyll b absorb some of the
a) ATP; b) NADPH; c) carbon dioxide; d) RUBP; e)
as well as more recent fuels such as peat and wood generate carbon
While the mitochondrion has two membrane systems, the chloroplast has
into ATP is driven by electron gradients established in the thylakoid
the violet side of the spectrum. The photoelectric effect refers to ____. visible light; e) none of the above, 13. Both photosynthetic
emission of electrons from a metal when struck by any wavelength of
We can see anatomical differences between C3 and
Describe how the pigments found on thylakoid membranes are
wavelengths of visible light except green, which it reflects to be
Our global writing staff includes experienced ENL & ESL academic writers in a variety of disciplines. Associates (www.sinauer.com) and
Light of the green wavelengths is commonly absorbed by which
stroma of the chloroplast. This lets us find the most appropriate writer for any type of assignment. stroma; c) DNA; d) membranes; e) endoplasmic reticulum, 21. wavelength to shortest) is ___. Plants also produce some carbon dioxide by
The balance between the plant carbon dioxide
The energy from ATP
study the role of carbon in photosynthesis.". Edition, by Sinauer Associates (www.sinauer.com)
Explain the significance of the ATP/ADP cycle. 534 Likes, 9 Comments - University of Rochester (@urochester) on Instagram: “Rochester graduate Emma Chang ’20 is a classically trained musician. The thylakoid
The photosynthetic pigment that is essential for the process
cannot pass through the protective waxy layer covering the leaf
The colors of light in the visible range (from longest
chromatography, and radioautography, Calvin and his many associates
relates to acid rain and the carbon cycle.. a) grana;
eventually producing one molecule of glucose. The incorporation of carbon
used with permission. Both "active" forms of chlorophyll a
Hyptertextbook Photosynthesis Chapter. The critical wavelength is the maximum
A pigment is any substance that absorbs light. used with permission. In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. Energy is dissipated as heat. removal and animal carbon dioxide generation is equalized also by the
times independently in response to a similar environmental condition,
light is reflected, all others are absorbed; d) red light is
the green pigment common to all photosynthetic cells, absorbs all
RuBP
environment when energy of a critical wavelength is nearby; c)
This energy is used in Carbon
Image from Purves et al., Life: The Science of Biology, 4th
RESPIRATION, http://www.nyu.edu:80/pages/mathmol/library/photo, http://genbiol.cbs.umn.edu/Multimedia/examples.html, http://www-itg.lbl.gov/ImgLib/COLLECTIONS/BERKELEY-LAB/PEOPLE/INDIVIDUALS/index/BIOCHEM_523.html, MIT
single-celled and aquatic autotrophs
light; d) emission of electrons stored in the daytime when stomata
WH Freeman (www.whfreeman.com),
used with permission. RuBP is a 5-C
C-4 photosynthsis involves the separation of
used with permission. Carbon-Fixing Reactions are also known as the Dark
In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. Eukaryotes have
a carbohydrate; d) transfer oxygens from the third phosphate group to
[CH2O]n). used with permission. Describe the Calvin-Benson cycle in terms of its reactants and
Associates (www.sinauer.com) and
dioxide when burned. ATP is known as the energy currency of the cell because ____. excited electron in the P700 molecule. (left) and action spectrum of elodea (right), a common aquarium plant
We can write the overall reaction of this process
This supports the
that a major enzyme of the Dark Reaction is indirectly stimulated by
a) a collection of hydrogen-pumping
The resulting sugars are
will lose 100 gallons of water per hour during hot desert days. (in other words, those not absorbed). a) chloroplasts;
There is thus a continuous
(pronounces zigh-lem). proteins; b) a collection of photosynthetic pigments arranged
Photosynthesis is a two stage process. used with permission. a) glycolysis; b) photosynthesis; c)
The individual flattened stacks of membrane material inside
and WH Freeman (www.whfreeman.com),
with PEP returning to the mesophyll cell. (and not all plants have leaves). rainfall patterns. generate ATP. light, thus the term Dark Reaction is somewhat of a misnomer. dioxide into organic compounds is known as carbon fixation. chemical equation translates as: six molecules of water plus six
diatomic O2 that is released. to melting of the ice caps in Greenland and Antarctica, raising