Chapter 5 photosynthesis
What is the 3 carbon compound called that happens after the reaction of CO2 and RuBP?
3- PGA
The 6 carbon compound in the first stage of the calvin cycle is immediately converted to
3-PGA
ATP uses its stored energy to convert ________ into ________, which is called a reduction reaction because of the gain in electrons.
3-PGA/ G3P
Plants did not move on land until
3.5 million years ago
Plants with C4 photosynthesis produce ______ as much glucose
3x
How many G3P molecules stay behind to regenerate RuBP
5
How many carbons does RuBP have?
5
How many G3P molecules regenerate RuBP
5 G3P
How is RuBP structured?
5 atoms of carbon and a phosphate group on each end
How much NADH is used in EACH cycle of the Calvin cycle?
6
In total, how many G3Ps are there in each cycle of the Calvin cycle? How many carbons?
6 G3Ps/ 18 carbons
How much ATP and NADH is required to split the 3-carbon compounds called 3-PGA into G3P?
6 of each
What is the regular photosynthesis called?
C-3 photosyntehsis
The purpose of the Calvin cycle is to allow the plant to produce ______ from glyceraldehyde 3-phosphate
G3P
What is the molecule that leaves the Calvin Cycle to be converted into glucose?
G3P
What molecule is produced and used to make glucose during the Calvin cycle?
G3P
Why won't C3 photosynthesis work in hot, arid environments?
Because the water will evaporate when stomata is open, but it needs to be open to prevent the build up of oxygen in the system
In plants with C4 photosynthesis, the rest of the Calvin cycle (not CO2 fixation) takes place in ______
Bundle sheath cells
How does RuBisCO catalyze the fixation reaction?
By combining CO2 with RuBP creating a 6 carbon compound
What are 2 types of energy carrier molecules
NADPH and ATP
What does photosystem I generate?
NADPH from NADP+
What is the name of enzyme involved in the carbon fixation stage of the Calvin cycle?
RuBisCO
ATP synthase is a
enzyme
The reduction reaction involves the ___________ of ____.
gain of electrons
Xanthophyls absorb _______ can't absorb _______
green/ red
When the hydrogen ions go through ATP synthase, they move from an area of _______ to an area of _____.
high concentration/ low concentration
Where is the chlorophyll molecule located in eukaryotic, photosynthetic organisms?
The thylakoid
What happens when the water is split?
There is Oxygen (O2) and hydrogen ions (H+) in the thylakoid space. OXygen is released
What do the membrane pumps do in the ETC?
They actively move hydrogen ions against their concentration gradient, from the stroma to the thylakoid space
What happens to the 6 carbon compounds?
They are broken down into two 3 carbon compounds called 3PGA The energy from ATP and NADPH is used to convert those molecules into G3P
What happens to the oxygen molecules when water is split?
They find their way to the surrounding environment
Where do light dependent reactions occur?
Thylakoid membrane
What happens to the electron after it is energized in the light dependent reaction?
Travels through electron transport chain → transferred into electrochemical gradient -→ picked up by NADH
The visible spectrum is a small sliver between ________ and _______
UV and infrared
thylakoid
a disc-shaped membranous structure inside a chloroplast where the light-dependent reactions of photosynthesis take place using chlorophyll embedded in the membranes
photon
a distinct quantity or "packet" of light energy
photosystem
a group of proteins, chlorophyll, and other pigments that are used in the light-dependent reactions of photosynthesis to absorb light energy and convert it into chemical energy
ATP synthase uses the energy from chemiosmosis to attach ______ to ____ creating _______
a phosphate group/ ADP/ ATP
granum
a stack of thylakoids located inside a chloroplast
Which statement correctly describes carbon fixation?
a. conversion of CO2 to an organic compound*** b. Use of RUBISCO to form 3-PGA c. Production of carbohydrate molecules from G3P d. formation of RUBP from G3P molecules
What does the chlorophyll do after its electron is replaced?
responds to another photon
C4 photosynthesis is a ________ for drier biomes
secondary adaptation
The stroma is the
space surrounding the granum
Plants produce oxygen when they photosynthesize. Where does the oxygen come from?
splitting water molecules
A double membrane surrounds the
stroma
The light dependent reactions occur in the membrane of the thylakoids and the Calvin cycle occurs in the _______ of the chloroplast
stroma
Where in plant cells does the Calvin cycle take place?
stroma
The membrane pump moves the hydrogen ions from the _______ to the ______.
stroma/ thylakoid space
C4 photosynthesis uses _______ to reduce water exposure
structural partitioning
What happens after RuBP is regenerated?
system starts carbon fixation all over again
In CAM photosynthesis the Calvin Cycle
takes place at night
In plants with C4 photosynthesis, mesophyll cells only fix CO2 because
that is separate from where water is held
If a mutation occurred in the ATP synthase complex, this would have an immediate effect on what photosynthetic process
the calvin cycle
stroma
the fluid-filled space surrounding the grana inside a chloroplast where the Calvin cycle reactions of photosynthesis take place
chlorophyll a
the form of chlorophyll that absorbs violet-blue and red light and does most of the work
Where is light trapped?
the grana
Where is the chlorophyll found on prokaryotes?
the infolding of the plasma membrane
What are the electrons in photosystem I replenished by?
the next electron in the chain
stoma
the opening that regulates gas exchange and water regulation between leaves and the environment; plural: stomata
chloroplast
the organelle where photosynthesis takes place
How many G3P molecules leave the Calvin Cycle to turn into flucose?
1
What 3 chemicals initiates the carbon dioxide formation?
1. CO2 2. enzyme RuBisCO 3. the molecule RuBP
The Calvin cycle is organized into three phases. They are:
1. Carbon dioxide fixation 2. Carbon dioxide reduction 3. Regeneration of RuBP
Describe the pathway of energy in light dependent reactions?
1. The energy is present initially as light. 2. A photon of light hits chlorophyll, causing an electron to be energized. 3. The free electron travels through the electron transport chain 4. Energy of the electron used to pump hydrogen ions into the thylakoid space / lumen 5. The energy is transferred into the electrochemical gradient 6. The energy of the electrochemical gradient is used to power ATP synthase 7. That energy adds a phosphate to ADP and makes ATP 8. Also, energy from another photon can be used to create a high-energy bond in the molecule NADPH
What are the two steps in photosynthesis
1. light dependent reaction 2. calvin cycle
4 integral membrane proteins found in the thylakoid are
1. photosystems I and II 2. Ctochrome b6f complex 3. ATP synthase
How much NADH is used to make one full molecule of glucose?
12
How many carbons are there when CO2 and RuBP react with each other
15 carbons from RuBP + 3 carbons from CO2 = 18 carbons/ 6 in one compound
How many ATP is used to make one full molecule of glucose?
18
How many "turns" of the Calvin cycle are needed to make one 6-carbon sugar?
2
Each breaking of a water molecule replaces ______ electrons, which can replace _____ donated electrons in the chlorophyll.
2/2
Over last 8,000 years, we lost _______ of the vegetation on this planet
2/3
How many RuBps are there in one cycle of the Calvin cycle
3
How much molecules of CO2 is used at a time in each Calvin cycle?
3
What energy molecule is used in the regeneration of RuBP? How many ?
3 ATP/ cycle
How much ATP is used in EACH cycle of the Calvin cycle?
9
How many molecules of ATP and NADPH are consumed in the Calvin Cycle?
9 molecules of ATP 6 molecules of NADPH
How is the electron in the chlorophyll replaced?
A molecule of H2O is split
How is photosynthesis initiated?
A photon strikes photosystem 2
Both the light reaction and the Calvin cycle use the carrier molecules ___________ to transport the energy from one to the other
ATP and NADH
What happens in carbon dioxide reduction
ATP and NADPH is used to convert the 3 carbon compound 3-PGA into another 3-carbon compound called G3P
What do photosystems do?
Act as an antenna to gather solar energy
Most grasses are ______
C4
In what type of photosynthesis does the plant separate the process by time of day?
CAM
Most succulents in the desert use
CAM photosynthesis
__________ are more stable and efficient reservoirs for chemical energy than _____
Carbohydrates/ ATP
photophosphorylation
In photosynthesis, when the ATP synthase uses the energy from the concentration gradient to attach a 3rd phosphate to ADP
What happens when the photon reaches chlorophyll?
It absorbs it and passes it along the pathway to other chlorophyll molecules
What does the electron in the chlorophyll molecule do after it becomes energized?
It breaks free from the atom of the chlorophyll
What happens when the energy culminates in the chlorophyll in the reaction center?
It causes an electron in the chlorophyll to become excited, or energize and leave that chlorophyll
What happens when the membrane pump moves the hydrogen ions?
It creates an electrochemical gradient
What happens to the electron after it breaks free from the chlorophyll?
It is transferred to a nearby primary electron acceptor
What happens to one of the G3P molecules?
It leaves the cycle so that it can contribute to the formation of the carbohydrate molecule
Which part of the Calvin cycle would be affected if a cell could not produce the enzyme RuBisCO?
None of the cycle could take place, because RuBisCO is essential in fixing carbon dioxide.
Describe the flow of the hydrogen ions
Pumped into thylakoid space → flow through electrochemical gradient → flow through ATP synthase → flow through stroma
What molecule attaches to CO2 in the beginning of the Calvin cycle?
RuBP
What molecule starts the Calvin Cycle? What molecule ends it?
RuBP
Which part of the Calvin cycle would be affected if a cell could not produce the enzyme RuBisCO?
Stage 1 - carbon fixation
What forms the electrochemical gradient in photosynthesis?
The build up of hydrogen ions in the thylakoid space
Prokaryotes do not have chloroplasts, so where does photosynthesis occur in protokaryotic organisms such as cyanobacteria
The plasma membranes of prokaryotes have in-foldings where chlorophyll molecules can be found
The hydrogen ions in photosynthesis is moved (against/with ) the concentration gradient
against
What can be determined by measuring wavelength
amount of energy
Plants that do CAM are
cactus and pineapple
Carbohydrate molecules have a backbone of
carbon atoms
If mutation occurs in rubisco, it would have an immediate effect on
carbon fixation
Plants are capable of both ________ and _____________ since they contain both __________ and _________.
cellular respiration & photosynthesis chloroplasts & mitochondria
Which molecule absorbs the energy of a photon in photosynthe
chlorophyll
What is the most common and abundant pigment?
chlorophyll A
Photosynthesis occurs in the ______ of plant cells, which is mostly found in the _________
chloroplast, mostly found in the leaves
Photosynthesis probably evolved from
cyanobacteria
What types of bacteria are autotrophs?
cyanobacteria
The hydrogen ions move ____________ through the enzyme _________ to create ATP
down their concentration gradient/ ATP synthase
In CAM photosynthesis the light reaction takes place
during the day
As energy travels through the electron transport chain, pumping hydrogen ions into the thylakoid space, an ___________ is formed
electrochemical gradient
The ______ in the pigment becomes energized when a photon hits it?
electron
What is the energy of a photon first used to do in photosynthesis?
energize an electron
Where do hydrogen ions build up during light-dependent reactions?
inside the thylakoid membrane
Chemiosmosis
ions flow through ATP synthase from the thylakoid space into stroma to form molecules of ATP
After the energy is released, the empty energy carriers return to _____________ to __________.
light dependent reactions/obtain more energy
In which part of the leaf does photosynthesis occur?
mesophyll
the middle layer of cells in a leaf
mesophyll
In plants with C4 photosynthesis, __________ cells only fix CO2
mesophyll cells
CO2 enters the ______ layer through __________and then diffuses into ________
mesophyll layer / stomata/ stroma of chloroplasts
Most photosynthetic organisms have a ________________ of pigments.
mixture
What happens to the 3 carbon molecules G3P
one leaves the cycle to become part of the carbohydrate molecule the other remains in the cycle to be formed back into RuBP, which then reacts with more CO2
The pigment molecules absorb ___ _______ of light energy at a time.
one photon
Cartenoids can't absorb ____, _______, _____ but can absorb ______ and _______.
orange, red, yellow/ greens and blues
CAM photosynthesis uses
partitioning in time
What type of autotroph uses sunlight and carbon to synthesize carbohydrates?
photoautotrophs
By what process does ATP synthase generate ATP from ADP?
photophosphorylation
After going through photosystem II and the ETC, the electron is accepted by a ______ in ____.
pigment / photosystem I
By opening stomata at night
plants eliminate potential evaporation
What is the molecule called that takes the electron in the ETC in the light dependent reaction?
primary electron acceptor
What happens if oxygen is built up in the photosynthesis system?
production of RuBP will shut down
Carbon dioxide reduction is also called a ________________
reduction reaction
Where are sugars made
the stroma
Metabolism is
the sum of all reactions in the body
What happens to ADP and NAD+ after the carbon dioxide reduction?
they return to the light dependent reaction to be reenergized
The membrane pouch where photosynthesis begins is the _________.
thylakoid
The thylakoid membrane encloses an internal space, called the
thylakoid space or lumen
A third membrane in the chlorplast forms the
thylakoids
What does ATP synthase do in light dependent reactions?
transfers energy (from electrochemical gradient) into a bond in the ATP molecule
Plants with C4 photosynthesis have a _________ output of energy
very high
The fraction of the electromagnetic spectrum which humans can see is called
visible light
Which type of electromagnetic radiation would be used by plants?
visible light
To replace the electron donated by the chlorophyll molecule in photosystem I, ______ is split and O2 and H+ ions are left in the thylakoid space
water
What is the term used to describe the measurement of the amount of energy in light?
wavelength
Absorption spectrum is the
wavelength that the pigment absorbs from the visible light
hydrolysis of water
when water is split into oxygen and hydrogen
Roots input water, which goes up into the plant in a system called
xylem
Chemiosmosis in photosynthesis
• The hydrogen ions are moved down their electrochemical gradient, through ATP synthase • The energy from the electrochemical gradient is harvested and stored as ATP
Adaptations for an increase in temp and reduction in moisture
• closing stomata to limit water loss • More efficient use of CO2 to allow plants to photosynthesize when CO2 is in short supply