Chapter 8 smartbook
If chloroplasts are isolated from a plant cell and exposed to light they release
Oxygen
When photosynthesis in the alga Chlorella was studied, scientists determined that the production of one molecule of ____ from water requires several thousand chlorophyll molecules.
Oxygen
On the following diagram of photosynthesis in the chloroplast, the thick arrow labeled with the letter A points to:
Photosystem I
Which photosystem's main function is to generate high-energy electrons for the synthesis of ATP?
Photosystem II
Recent studies with the atomic force microscope have shown that PSI and the ATP synthase are not randomly distributed in thylakoid membranes, rather, they seem concentrated ______
Primarily in the connections between grana (the stroma lamellae)
At low light intensities, how is the output of photosynthesis related to the intensity of illumination?
The output of photosynthesis increases linearly with increases in the intensity of illumination.
The following diagram shows the change in the rate of photosynthesis as a function of the intensity of light under varying conditions. Which of the following statements can be concluded based on the graph?
The rate of photosynthesis is limited by the concentration of CO2 at high light intensities. The rate of photosynthesis is limited by light at low light intensities. The rate of photosynthesis is limited by temperature at high light intensities.
Which of the following is an accurate description of carotenoids?
They are made of carbon rings connected to carbon chains with alternating single and double bonds.
Which of the following statements accurately compares the ATP synthase enzymes of chloroplasts and mitochondria?
They have similar structure and are evolutionarily related.
What is the net gain of the Calvin cycle?
Two molecules of G3P
Jan Baptista ___________ ___________ performed an experiment for which he grew a willow tree in a pot for several years, during which time he kept an exact record of changes in the weight of the soil.
Van Helmont
The _____ diagram describes the energy transitions of electrons as they move through the _____ reactions.
Z ; light-dependent
The role of light-harvesting complex is to
absorb photons of light
A graph depicting the efficiency of photon absorption by a pigment molecule as a function of photon wavelength is known as the
absorption spectrum of the pigment
Which of the following are the two components of a photosystem?
an antenna complex and a reaction center
In a photosystem, the _____ complex captures light energy and passes it to the _____ center where electrons are transferred out of the photosystem.
antenna; reaction
Reduced plastoquinone is a strong electron donor that passes a pair of electrons to ______.
b6-f complex
Review the diagram of photosynthesis in the chloroplast. What does the thick arrow labeled with the letter A point to?
b6-f complex
The ATP needed in the Calvin cycle comes from
both cyclic and noncyclic photophosphorylation
A C3 plant
can only fix carbon using the Calvin cycle
What molecule is released during photorespiration?
carbon dioxide
The two most important classes of pigments in chloroplasts are chlorophylls and ______.
carotenoids
_____ are accessory photosynthetic pigments that consist of carbon rings linked to chains with alternating single and double bonds.
carotenoids
Green plants utilize _____ a and b to absorb light energy in photosynthesis.
chlorophyll
In chloroplasts, the light-harvesting complex is composed of a web of _____ molecules linked together and held tightly in the thylakoid membrane by a matrix of proteins.
chlorophyll
Which of the following are used by green plants to absorb light energy?
chlorophyll a and chlorophyll b
Which are the two most important kinds of pigments in chloroplasts?
chlorophylls and carotenoids
In the reaction center of a photosystem, which of the following excited subatomic particles are transferred to an acceptor?
electrons
In the light-harvesting complex of the chloroplast, it is excitation _______, not the electrons themselves, that pass from one pigment molecule to the next.
energy
The ATP synthases of chloroplasts and mitochondria are
evolutionary related
The iron-sulfur protein ______ accepts electrons from photosystem I.
ferredoxin
In a green plant, the majority of photosynthesis takes place in
leaves
In a leaf, the thick layer of cells that are rich in chloroplasts is called the
mesophyll
In chloroplasts, when the two photosystems work in series, electrons ejected from the photosystems do not return to them, which is known as
noncyclic photophosphorylation
The process in which electrons from water move through PSII and PSI and ultimately to NADPH is also known as ___________
noncyclic photophosphorylation
Anoxygenic bacteria have how many photosystems?
one
The enzyme rubisco has more than one activity. Because of this, most plants also perform _________, which consumes oxygen and liberates carbon dioxide. This process can lower the net benefit from photosynthesis.
photorespiration
Almost all photosynthetic organisms capture light using
photosystems
In all photosynthetic organisms studied to date, except one class of photosynthetic bacteria, light is captured by clusters of chlorophyll and accessory pigment molecules, which together are called
photosystems
The primary electron acceptor for the excited electron leaving photosystem II is a _________ molecule.
plastoquinone
A chlorophyll molecule is made of a ____ ring and a ______ tail.
porphyrin, hydrocarbon
The range and efficiency of photons that a pigment molecule is capable of absorbing constitute its characteristic absorption
spectrum
What is the ultimate source of energy for almost all living cells on Earth?
sun
Once a photon is captured by the light harvesting complex, the pigments in it transfer
the energy of excited electrons but not electrons themselves
The energy used by most living cells comes ultimately from the ____ and is captured through the process of _____
the sun (photosynthesis)
The production of one molecule of O2 during photosynthesis requires how many chlorophyll molecules?
thousands
The function of the b6-f complex is to pump protons into the ______ space.
thylakoid
The inner (internal) membrane of the chloroplast is also called the ____ membrane.
thylakoid
The internal membrane of the chloroplast is also known as the
thylakoid membrane
Where do the light-dependent reactions of photosynthesis occur in the chloroplast?
thylakoid membrane
A Z diagram illustrates how many electron-energizing steps?
two
Chloroplasts have __ membrane(s).
two
How many different types of photosystems are found in chloroplasts?
two
Typically, it is considered that the net gain of the Calvin cycle is(are) ______________ molecule(s) of G3P.
two
Photosystem I passes electrons to
Ferredoxin
The role of the _____-harvesting complex in a photosystem is to directly absorb photons of light.
Light
The light-harvesting complex of a photosystem in a green plant contains a large number of _____
Pigments
What is the function of the b6-f complex?
To pump protons in the thylakoid space
The light- ______ reactions of photosynthesis occur on membranes.
dependent
The C4 pathway has a cost to plants, because the conversion of _________ to PEP requires the expenditure of ATP
pyruvate
Which of the following wavelengths of light are preferentially absorbed by chlorophyll molecules?
red, violet, and blue
A leaf that appears to be green to the human eye contains pigment molecules that are
reflecting green light
When light strikes a pigment, some wavelengths are absorbed and some are reflected. For instance, a leaf that appears green to the eye _____ green wavelengths of light.
reflects
Light has properties of both
waves and particles
Which of the following represents the phases of the Calvin cycle?
(1) carbon fixation; (2) reduction and carbohydrate production; (3) regeneration of ribulose bisphosphate
Consider the net equation that describes the Calvin cycle. How many NADPH are needed to synthesize the two net G3P molecules that can be used to make a glucose molecule?
12
The reaction center of photosystem I consists made of
12-14 protein subunits and 2 bound P700 chlorophyll molecules
When you take into account the net equation of the Calvin cycle, how many ATP molecules are needed to synthesize two G3P molecules?
18
The following diagram represents light absorption as a function of wavelength of various pigments. The pigment represented by the dotted line will absorb most strongly light with which of the following wavelengths?
470 nm
Which of the following are parts of a chlorophyll molecule?
A hydrocarbon tail A porphyrin ring
Chlorophyll _____ is the main photosynthetic pigment in plants as it converts light energy into chemical energy; chlorophyll _____ acts as an accessory pigment.
A;b
If chloroplasts are isolated from a plant and exposed to light in the absence of carbon dioxide, they accumulate
ATP
Photophosphorylation produces _______, which stores chemical energy that can be used for the Calvin cycle. Carbon fixation also requires reducing power, which is provided by ______ produced by photosystem I.
ATP and NADPH
Compared to the C3 pathway, the C4 pathway has an additional cost to a plant, because
ATP is required to convert pyruvate to PEP
The electron transport chain directly associated with photosystem II is used to generate _____, while the electron transport chain directly associated with photosystem I is used to generate ______.
ATP; NADPH
Which of the following organisms have only one photosystem?
Anoxygenic bacteria
A photosystem consists of two components, a(n) ______ complex and a(n)_______ center.
Antenna; reaction
Why is this Calvin cycle also known as C3 photosynthesis?
Because the first molecule in the cycle has 3 carbon atoms.
How do carotenoids assist in the photosynthetic process?
By capturing light wavelengths that are not efficiently absorbed by chlorophylls.
Plants that only fix carbon using the Calvin cycle are also known as ______ plants
C3
The Calvin cycle is also known as ________ photosynthesis because the first intermediate of the cycle contains three carbon atoms.
C3
The Calvin cycle is also known as __________ photosynthesis because the first intermediate of the cycle contains three carbon atoms.
C3
Plants that use _______ photosynthesis avoid water loss by closing their stomata during the day and opening them at night.
CAM
How do CAM plants avoid water loss?
CAM plants close their stomata during the day and open them at night.
According to the generalized equation for photosynthesis proposed by van Niel, CO2+2H2A+light energy yields which of the following?
CH2O+H2O+2A
Which of the following are phases of the Calvin cycle?
Carbon fixation Reduction and carbohydrate production Regeneration of ribulose bisphosphate
In photosynthesis, _____ molecules preferentially absorb violent-blue and red light.
Chlorophyll
Which of the following accurately describes pigments in the chloroplast?
Chlorophyll a is the main photosynthetic pigment in plants.
On the following diagram of the absorption spectra of various pigments, the dotted line shows the absorption spectrum of
Chlorophyll b
In van Niel's generalized equation of photosynthesis, which of the following is the donor of electrons?
H2A
Which of the following describes van Helmont's experiment?
He grew a willow in a pot keeping an exact record of the weight of the soil and the tree over several years.
The reaction center of photosystem ______ consists of a core transmembrane complex made of 12-14 protein subunits and two bound P700 chlorophyll molecules.
I (one)
According to recent studies, where are PSII and the b6-f complexes located?
In the grana and in borders between the grana and the stroma lamellae
Which of the following statements best describes the properties of light?
Light has properties of both a particle and a wave.
Similar to other pigments, carotenoids assist photosynthesis by capturing energy from ______, however, they absorb wavelengths that are not efficiently absorbed by ________. In addition, they scavenge _____ _______.
Light; Chlorophylls; Free radicals
How is the output of photosynthesis related to the amount of light available at different light intensities?
Linear increase at low light intensities and saturation at high light intensities