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46 terms

Photosynthesis: Light Reactions and The Calvin Cycle

Exam #2
STUDY
PLAY
Which of these equations best summarizes photosynthesis?
6 CO2 + 6 H2O → C6H12O6 + 6 O2
The light reactions of photosynthesis use _____ and produce _____.
water and NADPH
If photosynthesizing green algae are provided with CO2 synthesized with heavy oxygen (18O), later analysis will show that all but one of the following compounds produced by the algae contain the 18O label. That one is...
O2
Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
ATP and NADPH
Where does the Calvin cycle take place?
stroma of the chloroplasts
When oxygen is released as a result of photosynthesis, it is a by-product of which of the following
splitting the water molcules
Which term describes ATP production resulting from the capture of light energy by chlorophyll?
photophosphorylation
True or false? The chemiosmotic hypothesis states that the synthesis of ATP generates a proton gradient that leads to electron flow through an electron transport chain.
false
According to the chemiosmotic hypothesis, what provides the energy that directly drives ATP synthesis?
proton gradient
Which of the following particles can pass through the ATP synthase channel?
protons
True or false? The region of ATP synthase that catalyzes the production of ATP from ADP and inorganic phosphate spans the chloroplast membrane.
false
Chloroplast membrane vesicles are equilibrated in a simple solution of pH 5. The solution is then adjusted to pH 8. Which of the following conclusions can be drawn from these experimental conditions?
ATP will not be produced because there is no ADP and inorganic phosphate in the solution
Which process produces oxygen?
photosynthesis
Which set of reactions uses H2O and produces O2?
light-dependent reactions
What is the importance of the light-independent reactions in terms of carbon flow in the biosphere?
the light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars
True or false? The light-dependent reactions of photosynthesis use water and produce oxygen.
true
Which of the following molecules is the primary product of photosystem I?
NADPH
What is the biological significance of the light-independent reactions of photosynthesis?
they convert CO2 into sugar
Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis?
the light-dependent reactions produce ATP and NADPH, which are then used by light-independent reactions
Which of the following reactions ensures that the Calvin cycle can make a continuous supply of glucose?
regeneration of RuBP
The reaction-center chlorophyll of photosystem I is known as P700 because
this pigment is best at absorbing light with a wavelength of 700 nm
Which statement describes the functioning of photosystem II?
the electron vacancies in P680 are filled by electrons derived from water
Which of the following are directly associated with photosystem I?
receiving electrons from plastocyanin
What are the products of linear photophosphorylation?
ATP and NADPH
As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find 30,000 molecules of ATP consumed, but only 20,000 molecules of NADPH. Where did the extra ATP molecules come from?
cyclic electron flow
Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?
the synthesis of ATP
What does the chemiosmotic process in chloroplasts involve?
establishment of a proton gradient
In a plant cell, where are the ATP synthase complexes located?
thylakoid membrane and inner mitochondrial space
In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis translocates protons from
the stroma to the thylakoid space
Where are the molecules of the electron transport chain found in plant cells?
thylakoid membranes of chloroplasts
Synthesis of ATP by the chemiosmotic mechanism occurs during
both photosynthesis and respiration
Reduction of oxygen which forms water occurs during
respiration
Reduction of NADP+ occurs during
photosynthesis
Generation of proton gradients across membranes occurs during
both photosynthesis and respiration
Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?
they dissipate excessive light energy
Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?
the light reactions provide ATP and NADPH to the calvin cycle, and the cycle returns ADP, Pi, and NADP+ to the light reactions
Where do the enzymatic reactions of the Calvin cycle take place?
stroma of the chloroplast
What is the primary function of the Calvin cycle?
synthesize simple sugars from carbon dioxide
In the carbon fixation phase of the Calvin cycle, Rubisco attaches a molecule of carbon dioxide to a molecule containing five carbons. The resulting six-carbon compound is then split into two three-carbon molecules. After the reduction phase (including the exit of a single glyceraldehyde-3-phosphate molecule), what needs to happen next to complete a turn of the Calvin cycle?
regeneration of the five-carbon-containing molecule
The pH of the inner thylakoid space has been measured, as have the pH of the stroma and of the cytosol of a particular plant cell. Which, if any, relationship would you expect to find?
the pH within the thylakoid is less of that within the stroma
The light reactions of photosynthesis supply the Calvin cycle with
ATP and NADPH
Which of the following sequences correctly represents the flow of electrons during photosynthesis?
H2O > NADPH > calvin cycle
In mechanism, photophosphorylation is most similar to
oxidative phosphorylation is cellular respiration
Which process is most directly driven by light energy?
removal of electrons from chlorophyll molecules
Which of the following statements is a correct distinction between autotrophs and heterotrophs?
Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic
Which of the following does not occur during the Calvin cycle?
release of oxygen