Download Photosynthesis

Photosynthesis
Do Now: Complete both columns.
What do you think you know What do you want to know
about photosynthesis?
about photosynthesis?
• What do plants need for survival?
• 6H2O + 6CO2 ----------> C6H12O6+ 6O2
• Glucose is a ubiquitous fuel in biology. It is
used as an energy source in most organisms,
from bacteria to humans. Glucose is the
human body's key source of energy, through
aerobic respiration, providing approximately
3.75 kilocalories(16 kilojoules) of food
energy per gram.
• How do we know there is “glucose” in
plants?
• Glucose is soluble in water, hydrophilic, binds
with water and then takes up much space and
is osmotically active; glucose in the form of
starch, on the other hand, is not soluble,
therefore osmotically inactive and can be
stored much more compactly.
Activity time!!
• Photosynthesis is the process of converting
light energy to chemical energy and storing it
in the bonds of sugar. This process occurs in
plants and some algae (Kingdom Protista).
Plants need only light energy, CO2, and H2O to
make sugar. The process of photosynthesis
takes place in the chloroplasts, specifically
using chlorophyll, the green pigment involved
in photosynthesis.
• Chloroplasts were once bacteria
• Lynn Margulis- (Endosymbiotic theory)
• Thylakoids- membrane bound compartment
inside the chloroplast; the chlorophyll is built
into the membranes of the thylakoids; site of
photosynthesis.
A: What is the process of
photosynthesis used for?
• What do plants do in the winter for energy?
HW
• Create a one page summary of what you
learned today… use illustrations and/or
diagrams to help you.
S.A.
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1. The organic molecule produced directly by photosynthesis is: a) lipids; b) sugar;
c) amino acids; d) DNA
2. What is used and produced during photosynthesis? Can you write the
equation?
3. What organelle is responsible for photosynthesis?
4. What is the endosymbiotic theory?
5. How do you know plants have glucose?
6. Where is glucose stored? How?
7. What pigment is involved in photosynthesis?
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Starch or amylum is a carbohydrate consisting of a large number of glucose units .
The glucose is stored mainly in the form of starch granules, in plastids such as chloroplasts and
especially amyloplasts. Toward the end of the growing season, starch accumulates in twigs of trees
near the buds. Fruit, seeds, rhizomes, and tubers store starch to prepare for the next growing
season.
Glucose is soluble in water, hydrophilic, binds with water and then takes up much space and is
osmotically active; glucose in the form of starch, on the other hand, is not soluble, therefore
osmotically inactive and can be stored much more compactly.
When starch is mixed with iodine in water, an intensely colored starch/iodine complex is formed.
Many of the details of the reaction are still unknown. But it seems that the iodine (in the form of I5ions) gets stuck in the coils of beta amylose molecules (beta amylose is a soluble starch). The starch
forces the iodine atoms into a linear arrangement in the central groove of the amylose coil. There is
some transfer of charge between the starch and the iodine. That changes the way electrons are
confined, and so, changes spacing of the energy levels. The iodine/starch complex has energy level
spacings that are just so for absorbing visible light- giving the complex its intense blue color. The
complex is very useful for indicating redox titrations that involve iodine because the color change is
very sharp. It can also be used as a general redox indicator: when there is excess oxidizing agent,
the complex is blue; when there is excess reducing agent, the I5- breaks up into iodine and iodide
and the color disappears.
Starch Test: Add Iodine-KI reagent to a solution or directly on a potato or other materials such as
bread, crackers, or flour. A blue-black color results if starch is present. If starch amylose is not
present, then the color will stay orange or yellow. Starch amylopectin does not give the color, nor
does cellulose, nor do disaccharides such as sucrose in sugar.
Iodine Test: When following the changes in some inorganic oxidation reduction reactions, iodine
may be used as an indicator to follow the changes of iodide ion and iodine element. Soluble starch
solution is added. Only iodine element in the presence of iodide ion will give the characteristic blue
black color. Neither iodine element alone nor iodide ions alone will give the color result.
• Photosynthesis takes place primarily in plant leaves, and
little to none occurs in stems, etc. The parts of a typical leaf
include the upper and lower epidermis, the mesophyll,
the vascular bundle(s) (veins), and thestomates. The upper
and lower epidermal cells do not have chloroplasts, thus
photosynthesis does not occur there. They serve primarily
as protection for the rest of the leaf. The stomates are holes
which occur primarily in the lower epidermis and are for air
exchange: they let CO2 in and O2 out. The vascular bundles
or veins in a leaf are part of the plant's transportation
system, moving water and nutrients around the plant as
needed. The mesophyll cells have chloroplasts and this is
where photosynthesis occurs.
• As you hopefully recall, the parts of a chloroplast include the outer
and inner membranes, intermembrane space, stroma,
and thylakoids stacked in grana. The chlorophyll is built into the
membranes of the thylakoids.
• Chlorophyll looks green because it absorbs red and blue light,
making these colors unavailable to be seen by our eyes. It is the
green light which is NOT absorbed that finally reaches our eyes,
making chlorophyll appear green. However, it is the energy from
the red and blue light that are absorbed that is, thereby, able to be
used to do photosynthesis. The green light we can see is not/cannot
be absorbed by the plant, and thus cannot be used to do
photosynthesis.
• The overall chemical reaction involved in photosynthesis is: 6CO2 +
6H2O (+ light energy) C6H12O6 + 6O2. This is the source of the O2 we
breathe, and thus, a significant factor in the concerns about
deforestation
• There are two parts to photosynthesis:
• The light reaction happens in the thylakoid membrane and
converts light energy to chemical energy. This chemical
reaction must, therefore, take place in the light. Chlorophyll
and several other pigments such as beta-carotene are
organized in clusters in the thylakoid membrane and are
involved in the light reaction. Each of these differentlycolored pigments can absorb a slightly different color of
light and pass its energy to the central chlorphyll molecule
to do photosynthesis. The central part of the chemical
structure of a chlorophyll molecule is a porphyrin ring,
which consists of several fused rings of carbon and nitrogen
with a magnesium ion in the center.
• The energy harvested via the light reaction is
stored by forming a chemical called ATP
(adenosine triphosphate), a compound used
by cells for energy storage. This chemical is
made of the nucleotide adenine bonded to a
ribose sugar, and that is bonded to three
phosphate groups. This molecule is very
similar to the building blocks for our DNA.
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http://biology.clc.uc.edu/courses/bio104/photosyn.htm
• The dark reaction takes place in the stroma
within the chloroplast, and converts CO2 to sugar.
This reaction doesn't directly need light in order
to occur, but it does need the products of the
light reaction (ATP and another chemical called
NADPH). The dark reaction involves a cycle called
the Calvin cycle in which CO2 and energy from
ATP are used to form sugar. Actually, notice that
the first product of photosynthesis is a threecarbon compound called glyceraldehyde 3phosphate. Almost immediately, two of these join
to form a glucose molecule.
• Most plants put CO2 directly into the Calvin cycle. Thus the first stable
organic compound formed is the glyceraldehyde 3-phosphate. Since that
molecule contains three carbon atoms, these plants are called C3 plants.
For all plants, hot summer weather increases the amount of water that
evaporates from the plant. Plants lessen the amount of water that
evaporates by keeping their stomates closed during hot, dry weather.
Unfortunately, this means that once the CO2 in their leaves reaches a low
level, they must stop doing photosynthesis. Even if there is a tiny bit of
CO2 left, the enzymes used to grab it and put it into the Calvin cycle just
don't have enough CO2 to use. Typically the grass in our yards just turns
brown and goes dormant. Some plants like crabgrass, corn, and sugar
cane have a special modification to conserve water. These plants capture
CO2 in a different way: they do an extra step first, before doing the Calvin
cycle. These plants have a special enzyme that can work better, even at
very low CO2 levels, to grab CO2 and turn it first into oxaloacetate, which
contains four carbons. Thus, these plants are called C4 plants. The CO2 is
then released from the oxaloacetate and put into the Calvin cycle. This is
why crabgrass can stay green and keep growing when all the rest of your
grass is dried up and brown.
• There is yet another strategy to cope with very hot, dry,
desert weather and conserve water. Some plants (for
example, cacti and pineapple) that live in extremely hot,
dry areas like deserts, can only safely open their stomates
at night when the weather is cool. Thus, there is no chance
for them to get the CO2needed for the dark reaction during
the daytime. At night when they can open their stomates
and take in CO2, these plants incorporate the CO2 into
various organic compounds to store it. In the daytime,
when the light reaction is occurring and ATP is available
(but the stomates must remain closed), they take the
CO2from these organic compounds and put it into the
Calvin cycle. These plants are called CAM plants, which
stands for crassulacean acid metabolism after the plant
family, Crassulaceae (which includes the garden
plant Sedum) where this process was first discovered.
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http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookps.html
• 6H2O + 6CO2 ----------> C6H12O6+ 6O2
• Water enters the root and is transported up to the leaves through
specialized plant cells known as xylem (pronounces zigh-lem). Land
plants must guard against drying out (desiccation) 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 (the stoma; plural = stomata; Greek for
hole) flanked by two guard cells. Likewise, oxygen produced during
photosynthesis can only pass out of the leaf through the opened
stomata. Unfortunately for the plant, while these gases are moving
between the inside and outside of the leaf, a great deal water is
also lost. Cottonwood trees, for example, will lose 100 gallons of
water per hour during hot desert days. Carbon dioxide enters
single-celled and aquatic autotrophs through no specialized
structures.
• Photosynthesis is the process by which plants, some bacteria,
and some protists use the energy from sunlight to produce
sugar, which cellular respiration converts into ATP, the "fuel"
used by all living things. 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. Oh yes, we
need the food as well!
• Chlorophyll is a complex molecule. Several modifications of chlorophyll
occur among plants and other photosynthetic organisms. All
photosynthetic organisms (plants, certain protistans, prochlorobacteria,
and cyanobacteria) have chlorophyll a. Accessory pigments absorb energy
that chlorophyll a does not absorb. Accessory pigments include chlorophyll
b (also c, d, and e in algae and protistans), xanthophylls,
and carotenoids (such as beta-carotene). Chlorophyll a absorbs its energy
from the Violet-Blue and Reddish orange-Red wavelengths, and little from
the intermediate (Green-Yellow-Orange) wavelengths.
http://www.nyu.edu:80/pages/mathmol/library/photo
http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookps.html
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1. The organic molecule produced directly by photosynthesis is: a) lipids; b) sugar; c) amino acids; d)
DNA
2. The photosynthetic process removes ___ from the environment. a) water; b) sugar; c) oxygen; d)
chlorophyll; e) carbon dioxide
3. The process of splitting water to release hydrogens and electrons occurs during the _____
process. a) light dependent; b) light independent; c) carbon fixation; d) carbon
photophosphorylation; e) glycolysis
4. The process of fixing carbon dioxide into carbohydrates occurs in the ____ process. a) light
dependent; b) light independent; c) ATP synthesis; d) carbon photophosphorylation; e) glycolysis
5. Carbon dioxide enters the leaf through ____. a) chloroplasts; b) stomata: c) cuticle; d) mesophyll
cells; e) leaf veins
6. The cellular transport process by which carbon dioxide enters a leaf (and by which water vapor
and oxygen exit) is ___. a) osmosis; b) active transport; c. co- transport; d) diffusion; e) bulk flow
7. Which of the following creatures would not be an autotroph? a) cactus; b) cyanobacteria; c) fish;
d) palm tree; e) phytoplankton
8. The process by which most of the world's autotrophs make their food is known as ____. a)
glycolysis; b) photosynthesis; c) chemosynthesis; d) herbivory; e) C-4 cycle
9. The process of ___ is how ADP + P are converted into ATP during the Light dependent process. a)
glycolysis; b) Calvin Cycle; c) chemiosmosis; d) substrate-level phosphorylation; e) Kreb's Cycle
10. Once ATP is converted into ADP + P, it must be ____. a) disassembled into components (sugar,
base, phosphates) and then ressembled; b) recharged by chemiosmosis; c) converted into NADPH;
d) processed by the glycolysis process; e) converted from matter into energy.
11. Generally speaking, the longer the wavelenght of light, the ___ the available energy of that
light. a) smaller; b) greater; c) same
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12. The section of the electromagnetic spectrum used for photosynthesis is ___. a) infrared; b)
ultraviolet; c) x-ray; d) visible light; e) none of the above
13. The colors of light in the visible range (from longest wavelength to shortest) is ___. a) ROYGBIV;
b) VIBGYOR; c) GRBIYV; d) ROYROGERS; e) EBGDF
14. The photosynthetic pigment that is essential for the process to occur is ___. a) chlorophyll a; b)
chlorophyll b; c) beta carotene; d) xanthocyanin; e) fucoxanthin
15. When a pigment reflects red light, _____. a) all colors of light are absorbed; b) all col;ors of light
are reflected; c) green light is reflected, all others are absorbed; d) red light is reflected, all others
are absorbed; e) red light is absorbed after it is reflected into the internal pigment molecules.
16. Chlorophyll a absorbs light energy in the ____color range. a) yellow-green; b) red-organge; c)
blue violet; d) a and b; e) b and c.
17. A photosystem is ___. a) a collection of hydrogen-pumping proteins; b) a collection of
photosynthetic pigments arranged in a thylakjoid membrane; c) a series of electron-accepting
proteins arranged in the thylakoid membrane; d. found only in prokaryotic organisms; e) multiple
copies of chlorophyll a located in the stroma of the chloroplast.
18. The individual flattened stacks of membrane material inside the chloroplast are known as ___.
a) grana; b) stroma; c) thylakoids; d) cristae; e) matrix
19. The fluid-filled area of the chloroplast is the ___. a) grana; b) stroma; c) thylakoids; d) cristae; e)
matrix
20. The chloroplast contains all of these except ___. a) grana; b) stroma; c) DNA; d) membranes; e)
endoplasmic reticulum
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21. The chloroplasts of plants are most close in size to __. a) unfertilized human
eggs; b) human cheek cells; c) human nerve cells; d) bacteria in the human mouth;
e) viruses
22. Which of these photosynthetic organisms does not have a chloroplast? a)
plants; b) red algae; c) cyanobacteria; d) diatoms; e) dinoflagellates
23. The photoelectric effect refers to ____. a) emission of electrons from a metal
when energy of a critical wavelength strikes the metal; b) absorbtion of electrons
from the surrounding environment when energy of a critical wavelength is nearby;
c) emission of electrons from a metal when struck by any wavelength of light; d)
emission of electrons stored in the daytime when stomata are open at night; e)
release of NADPH and ATP energy during the Calvin Cycvle when light iof a specific
wavelength strikes the cell.
24. Light of the green wavelengths is commonly absorbed by which accessory
pigment? a) chlorophyll a; b) chlorophyll b; c) phycocyanin; d) beta carotene
25. The function of the electron transport proteins in the thyakoid membranes is
___. a) production of ADP by chemiosmosis; b) production of NADPH by substratelevel phosphorylation; c) pumping of hydrogens into the thylakoid space for later
generation of ATP by chemiosmosis; d) pumping of hydrogens into the inner
cristae space for later generation of ATP by chemiosmosis; e) preparation of water
for eventual incorporation into glucose
26. ATP is known as the energy currency of the cell because ____. a) ATP is the
most readily usable form of energy for cells; b) ATP passes energy along in an
electron transport chain; c) ATP energy is passed to NADPH; d) ATP traps more
energy than is produced in its formation; e) only eukaryotic cells use this energy
currency.
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27. Both cyclic and noncyclic photophosphorylation produce ATP. We can infer that the purpose of
ATP in photosynthesis is to ____. a) supply hydrogen to the carbohydrate; b) supply carbon to the
carbohydrate; c) supply energy that can be used to form a carbohydrate; d) transfer oxygens from
the third phosphate group to the carbohydrate molecule; e) convert RuBP into PGA
28. The role of NADPH in oxygen-producing photosynthesis is to ____. a) supply hydrogen to the
carbohydrate; b) supply carbon to the carbohydrate; c) supply energy that can be used to form a
carbohydrate; d) transfer oxygens from the third phosphate group to the carbohydrate molecule; e)
convert RuBP into PGA.
29. The dark reactions require all of these chemicals to proceed except ___. a) ATP; b) NADPH; c)
carbon dioxide; d) RUBP; e) oxygen
30. The first stable chemical formed by the Calvin Cycle is _____. a) RUBP; b) RU/18; c) PGA; d)
PGAL; e) Rubisco
31. The hydrogen in the carbohydrate produced by the Calvin Cycle comes from ___ a.) ATP; b)
NADPH; c) the environment if the pH is very acidic; d) a and b; e) a and c
32. The carbon incorporated into the carbohydrate comes from ___. a) ATP; b) NADPH; c) carbon
dioxide; d) glucose; e) organic molecules
33. C-4 photosynthesis is so named because _____. a) it produces a three carbon compound as the
first stable product of photosynthesis; b) it produces a four carbon compound as the first stable
produc of photosynthesis; c) it produces four ATP and four NADPH molecules for carbon fixation.; d)
there are only four steps in this form of carbon fixation into carbohydrate.