Biology Chapter 10: Photosynthesis
___________, the main ingredient, in cell walls, is the most abundant organic molecule in the plant and possibly the world.
cellulose
By what process do the light reactions generate ATP?
chemiosmosis
Chloroplasts and mitochondria generate ATP by the same basic mechanism: _____________.
chemiosmosis
____________ is the green pigment that gives leaves their color.
chlorophyll
Each reaction-center complex has a special pair of ___________ molecules.
chlorophyll a
_______________ is the key light-capturing ingredient in the light reactions.
chlorophyll a
The first step of the light reactions is the solar-powered transfer of an electron from the reaction-center ______________ to the ______________.
chlorophyll a pair, primary electron acceptor
Each light-harvesting complex consists of various pigment molecules, which can include ___________________.
chlorophyll a, chlorophyll b, carotenoids
What are the three types of pigments in chloroplasts?
chlorophyll a, chlorophyll b, carotenoids
All green parts of a plant have __________.
chloroplasts
Where does the Calvin Cycle occur in C4 plants?
chloroplasts of bundle-sheath cells
On a hot, dry day, most plants __________ their stomata to conserve water.
close
In certain cases, photoexcited electrons can take an alternative path called ___________.
cyclic electron flow
The Calvin Cycle is often called ___________ or ____________ because none of it requires light directly.
dark reactions, light-independent
_______________ consume the remains of dead organisms by decomposing and feeding on organic litter such as carcasses, feces, and fallen leaves.
decomposers
Photorespiration __________ photosynthetic output; it is considered a(n) _____________ process.
decreases, wasteful
In cellular respiration, electrons go __________ the electron transport chain, an exergonic process; in photosynthesis, electrons go _____________ the electron transport chain, an endergonic process.
down, up
When is CO2 released from CAM plants?
during the day, when the light reactions can be completed to provide fuel for the Calvin Cycle
_____________ occurs during the light reactions and causes electrons to flow through through the photosystems.
linear electron flow
The light reactions occur in the ___________ of the chloroplast.
thylakoids
Within the bundle-sheath cells, the 4-carbon compounds release _________, which is reassimilated into organic material by rubisco and the Calvin Cycle. This generates _________, which is transported to mesophyll cells. There, _________ is used to convert pyruvate to _______, and the cycle continues.
CO2, pyruvate, ATP, PEP
Carbon enters the Calvin Cycle in the form of ____________ and leaves as ____________.
CO2, sugar
The entire range of radiation is called the _______________.
EM spectrum
In reduction, a pair of electrons donated from NADPH reduces 1,3-bisphosphoglycerate to _______________.
G3P
In the light reactions, _______________ are added to ___________ to produce NADPH.
H+ and electron pair, NADP+
Where does the O2 given off in photosynthesis come from (what reactant)?
H2O
_________ is the electron acceptor used in photosynthesis.
NADP+
In the light reactions, electrons are pushed from water to ____________, the process of which also generates _________.
NADPH, ATP
Light energy in the light reactions is converted into ___________ and ___________.
NADPH, ATP
The Calvin Cycle makes sugar with the help of __________ and ___________ produced by the light reactions.
NADPH, ATP
The light reactions produce ____________, ____________, and ______________.
NADPH, ATP, oxygen
Rubisco is capable of binding _______ in place of CO2.
O2
The light reactions generate ATP by adding ____________ to ___________.
P, ADP
The form of P680 that loses an electron to the primary electron acceptor is called ___________.
P680+
____________ is the strongest biological oxidizing agent known.
P680+
The reaction-center chlorophyll a of photosystem II is known as __________ because the pigment best absorbs light with a wavelength of __________ nm.
P680, 680
The reaction-center chlorophyll a of photosystem I is known as ______________ because the pigment best absorbs light with a wavelength of ___________ nm.
P700, 700
What is the enzyme present only in mesophyll cells?
PEP carboxylase
___________ can fix carbon efficiently when rubisco cannot.
PEP carboxylase
What photosystems can be found in bundle-sheath cells?
PSI
In carbon fixation, CO2 molecules are attached one at a time to a 5-carbon sugar called __________.
RuBP
_________ molecules of 3-phosphoglycerate are formed for each CO2 molecule fixed.
2
G3P requires _________ CO2 molecules.
3
The Calvin Cycle occurs _____________ times for every molecule of G3P.
3
________ ATP molecules are used in the regeneration of RuBP.
3
In the regeneration of the CO2 acceptor (RuBP), __________ molecules of G3P are rearranged into ________ molecules of RuBP.
3, 5
What is the direct sugar product of photosynthesis?
3-carbon sugar used to make glucose
Visible light is between ___________ and ____________ nm.
380, 750
C4 plants are so named because they preface the Calvin Cycle with an alternate mode of carbon fixation that forms a(n) ______________ as its first product.
4-carbon compound
About __________% of the organic material made by photosynthesis is consumed as fuel for cellular respiration in mitochondria.
50
Photorespiration drains away as much as ________% of the carbon fixed by the Calvin Cycle.
50
Of the __________ G3P molecules formed in the Calvin Cycle, ________ exits to be used by the plant cell, while the rest are recycled.
6, 1
What is the formula for photosynthesis?
6CO2+12H2O+light energy------>C6H12O6+6O2+6H2O
For the net synthesis of one G3P, the Calvin Cycle consumes _________ ATP molecules and ____________ NADPH molecules.
9, 6
Cyclic electron flow generates _________ but does not produce _________ or ____________.
ATP, NADPH, O2
A(n) ___________ spectrum plots a pigment's light absorption versus its wavelength.
absorption
A(n) ______________ spectrum plots the relative effectiveness of different wavelengths of radiation in driving the process.
action
Plants that fix carbon via rubisco are called _________ plants.
C3
In __________ plants, the initial steps of carbon fixation are separated from the Calvin Cycle, whereas in ___________ plants, the two steps occur at separate times in the same cell.
C4, CAM
What are the two alternate modes of carbon fixation and what do they do?
C4, CAM; minimize photorespiration and optimize the Calvin Cycle
The carbon fixation method of taking up CO2 at night and incorporating it into organic acids is called _________.
CAM
The closing of the stomata reduces photosynthetic yield by limiting access to ___________.
CO2
When rubisco replaces CO2 with O2, it begins feeding O2 into the Calvin Cycle, releasing __________.
CO2
PEP carboxylase adds ______ to PEP, forming the 4-carbon product _________________.
CO2, oxaloacetate
In reduction, each molecule of 3-phosphoglycerate receives ____________ from ATP, becoming 1,3-bisphosphoglycerate.
an additional phosphate
CAM plants open their stomata ___________ and close them ____________.
at night, during the day
Almost all plants are _________.
autotrophs
__________ are called the "producers" of the biosphere.
autotrophs
______________ sustain themselves without eating anything derived from other living beings; they produce their own organic molecules from CO2 and other inorganic raw materials.
autotrophs
_______________ are arranged into tightly packed sheaths around the veins of a leaf.
bundle-sheath cells
After the C4 plant fixes carbon, the mesophyll cells transport their 4-carbon products to _____________ through __________________.
bundle-sheath cells, plasmodesmata
What 2 types of photosynthetic cells are found in C4 plants?
bundle-sheath, mesophyll
The citric acid cycle is ___________, while the Calvin cycle is ___________.
catabolic, anabolic
The enzyme that catalyzes carbon fixation is called __________.
rubisco
______________ is the most abundant protein on Earth.
rubisco
Microscopic pores by which CO2 enters the leaves and O2 exits are called __________.
stomata
A chloroplast has an envelope of two membranes surrounding a dense fluid called the _____________.
stroma
The Calvin Cycle occurs in the ____________ of the chloroplast.
stroma
The mitochondrial matrix is comparable to the _____________ of the chloroplast.
stroma
The thylakoid membrane of the chloroplast pumps protons from the ____________ to the ____________.
stroma, thylakoid space
CAM plants include _____________ (water-storing) plants.
succulent
Neither the light reactions nor the Calvin Cycle alone can make ___________ from CO2.
sugar
The light reactions DO NOT PRODUCE ___________; this is produced in the Calvin Cycle.
sugar
Unlike photosynthesis, what does photorespiration not produce?
sugar
NAD+ and NADP+ differ only in ________________.
the additional phosphate group in NADP+
The distance between the crests of EM waves is called the ____________.
wavelength
Each pigment has a unique absorption spectrum because a particular compound absorbs only photons corresponding to specific ___________.
wavelengths
Can cyclic electron flow occur in species that possess both photosystems?
yes
Do plant cells complete cellular respiration and photosynthesis?
yes
When a molecule absorbs a photon of light, an electron is elevated to an orbital with more potential energy; this state is referred to as a(n) _____________ state of chlorophyll.
excited
In linear electron flow, electrons transfer from one photon to the next; when they are absorbed, they reach a(n) __________ state, falling back to their __________ state as their electrons are transferred to the next photon.
excited, ground
Cyclic electron flow occurs only in photosytem _________.
I
Photosytem _________ functions first in the light reactions.
II
Bundle-sheath cells carry out ____________ electron flow.
cyclic
_____________ participate in photoprotection by absorbing and dissipating excessive light energy that would otherwise be damaging to the cell.
carotenoids
CH2O is not an actual sugar; it represents the general formula for a(n) __________.
carbohydrate
The Calvin Cycle reduces fixed carbon to ____________ by the addition of electrons.
carbohydrates
______________ is the initial incorporation of CO2 into organic compounds.
carbon fixation
What are the 3 stages of the Calvin Cycle?
carbon fixation, reduction, regeneration of the CO2 acceptor
___________ broaden the spectrum of colors that can drive photosynthesis.
carotenoids
Heterotrophs can obtain nutrients in what ways?
eating plants or animals, decomposing
Light is a form of _____________ energy.
electromagnetic
Linear electron flow causes electrons to be transferred from PSII to PSI via a(n) ______________.
electron transport chain
Both cellular respiration and photosynthesis involve ____________ and _____________ as mechanisms for chemiosmosis.
electron transport chains, ATP synthases
When excited electrons fall back to their ground state, photons are given off, an afterglow called __________.
fluorescence
Mitochondria use chemiosmosis to transfer chemical energy from __________ to ATP, while chloroplasts transform ____________ into ____________ in ATP.
food molecules, light energy, chemical energy
The carbohydrate produced directly by the Calvin Cycle is not glucose, but ______________.
glyceraldehyde 3-phosphate (G3P)
A stack of thylakoids is called a(n) ____________.
granum (plural: grana)
The shorter the wavelength, the ____________ the energy of each photon of that light.
greater
_____________ are the "consumers" of the biosphere.
heterotrophs
________________ obtain organic materials by living on compounds produced by other organisms.
heterotrophs
Almost all ____________ are completely dependent, either directly or indirectly, on _______________ for food as well as oxygen.
heterotrophs, photoautotrophs
What is the difference between photophosphorylation in chloroplasts and oxidative phosphorylation in mitochondria?
in chloroplasts, electrons in transport chain come from water; in mitochondria, they're extracted from organic molecules
The ______________ in the mitochondrion serves as a reservoir of H+.
intermembrane space
What part of a plant is where photosynthesis occurs?
leaves
Each photosystem converts ___________ to ____________.
light energy to chemical energy
The ____________ stage of photosynthesis is what converts solar energy to chemical energy.
light reactions
What are the two stages of photosynthesis?
light reactions, Calvin Cycle
Chloroplasts are found mainly in the cells of the _____________.
mesophyll
______________ is the tissue in the interior of the leaf.
mesophyll
Loosely arranged ______________ are found between the bundle-sheath cells and leaf surface.
mesophyll cells
The ___________ cells of CAM plants store the organic acids they make during the night in their ____________ until morning, when the stomata close.
mesophyll, vacuoles
The inner membrane of the mitochondrion pumps protons from the _____________ to the _____________.
mitochondrial matrix, intermembrane space
Do chloroplasts need molecules from food to make ATP?
no; they only need sunlight and water
Electron transport chains transform ________ energy to a(n) _____________.
redox, proton-motive force
The Calvin Cycle begins by incorporating CO2 from the air into ___________ already present in the chloroplast.
organic molecules
_____________ use light as a source of energy to synthesize organic substances.
photoautotrophs
____________ are discrete particles of light.
photons
The addition of P to ADP, forming ATP in the light reactions, is called _____________.
photophosphorylation
There is a theory that cyclic electron flow still exists in plants despite it being evolutionarily unnecessary because it is __________.
photoprotective
The process of _____________ consumes O2 while producing CO2.
photorespiration
C4 photosynthesis spends ATP energy to minimize __________ and enhance ______________.
photorespiration, sugar production
The process of converting sunlight to chemical energy stored in sugar and other organic molecules is __________.
photosynthesis
A(n) ______________ is composed of a reaction-center complex surrounded by several light-harvesting complexes.
photosystem
There are two types of photosystems in the thylakoid membrane: _______________ and ____________.
photosystem II, photosystem I
In the thylakoid membrane, chlorophyll molecules are arranged into ___________.
photosystems
When a pigment molecule absorbs a photon, the energy is transferred from ___________ to ______________ within a light-harvesting complex, until it is passed into the _______________.
pigment molecule, pigment molecule, reaction-center complex
Substances that absorb visible light are called ___________.
pigments
What is proton-motive force?
potential energy stored in the form of an H+ gradient across a membrane
The reaction-center complex contains a molecule capable of accepting electrons and becoming reduced; this is called the _____________.
primary electron acceptor
In some cases, photorespiration plays a(n) ______________ role in plants, neutralizing the damage caused by the light reactions.
protective
Both cellular respiration and photosynthesis involve __________ reactions.
redox
What is the relationship between cellular respiration and photosynthesis?
the overall chemical change during photosynthesis is the reverse of the one that occurs during cellular respiration
What powers life on Earth?
the sun
In which part of the chloroplast is chlorophyll found?
thylakoid membranes
The _________________ in the chloroplast serves as a reservoir of H+.
thylakoid space
The intermembrane space of the mitochondrion is comparable to the ____________ of the chloroplast.
thylakoid space
Suspended within the stroma of a chloroplast is the membrane system made up of sacs called ____________.
thylakoids
_____________ segregate the stroma from the thylakoid space inside of the sacs.
thylakoids
___________ is the evaporative loss of water from leaves.
transpiration
The excited electron state is _________.
unstable
Photorespiration does not generate ATP; instead, it _____________.
uses it
Water absorbed by the roots is delivered to the leaves in _____________.
veins
___________ in leaves are used to deliver water from the roots to the leaves and to export sugar to roots.
veins
We see green when looking at a leaf because chlorophyll absorbs ____________ light while reflecting __________ light.
violet-blue and red, green
___________ light is what drives photosynthesis.
visible