ch 10 mb photosynthesis
Which of the following statements is not true of most cellular redox reactions? A) The electron acceptor is reduced, acting as a reducing agent. B) The electron acceptor is reduced, acting as an oxidizing agent. C) The reactant that is reduced gains electrons. D) The reactant that is oxidized loses electrons, acting as a reducing agent.
The electron acceptor is reduced, acting as a reducing agent.
he overall function of the Calvin cycle is _____
making sugar
The ultimate source of energy to support most life on Earth is _____
sunlight
Which wavelengths of light drive the highest rates of photosynthesis? Select the two best answers.
400-450 nm and 670-680 nmLight in the violet-blue and red portions of the spectrum is most effective in driving photosynthesis.
Which of these equations best summarizes photosynthesis?
6 CO2 + 6 H2O → C6H12O6 + 6 O2
Identify the chloroplast.
green dots
Which process produces oxygen?
photosynthesis
CO2 is unusable until ______________ have "fixed" this carbon into sugar.
plants
The light reactions of photosynthesis supply the Calvin cycle with
ATP and NADPH.
Using the ATP and NADPH made during the light reactions, carbon is reduced in the ________ ______ and sugar is made.
Calvin cycle
______________ pathways build molecules, require energy, and are endergonic.
Anabolic
What is the basic role of CO2 in photosynthesis?
CO2 is fixed or incorporated into organic molecules.
The photosynthetic membranes are found in the _____ in plant cells.
Chorolplast
The net reaction of the Calvin cycle is the conversion of CO2 into the three-carbon sugar G3P. Along the way, reactions rearrange carbon atoms among intermediate compounds and use the ATP and NADPH produced by the light reactions. In this exercise, you will track carbon atoms through the Calvin cycle as required for the net production of one molecule of G3P. For each intermediate compound in the Calvin cycle, identify the number of molecules of that intermediate and the total number of carbon atoms contained in those molecules. As an example, the output G3P is labeled for you: 1 molecule with a total of 3 carbon atoms. Labels may be used once, more than once, or not at all.
Counting carbons—keeping track of where the carbon atoms go in each reaction—is a simple way to help understand what is happening in the Calvin cycle. To produce 1 molecule of G3P (which contains 3 carbons), the Calvin cycle must take up 3 molecules of CO2 (1 carbon atom each). The 3 CO2 molecules are added to 3 RuBP molecules (which contain 15 total carbon atoms), next producing 6 molecules of 3-PGA (18 total carbon atoms). In reducing 3-PGA to G3P (Phase 2), there is no addition or removal of carbon atoms. At the end of Phase 2, 1 of the 6 G3P molecules is output from the cycle, removing 3 of the 18 carbons. The remaining 5 G3P molecules (15 total carbon atoms) enter Phase 3, where they are converted to 3 molecules of R5P. Finally, the R5P is converted to RuBP without the addition or loss of carbon atoms.
What happens along an electron transport chain?
Electrons are passed from a reducing agent to an oxidizing agent, releasing free energy at each step.
Select the correct molecule that is the main product of the Calvin cycle. a) NADPH b) G3P c) Glucose
G3P
The electrons derived from the oxidation reaction in the Calvin cycle are used to reduce CO2 to ____________
G3P.
Which of the following sequences correctly represents the flow of electrons during photosynthesis? A. H2O > NADPH > Calvin Cycle B. NADPH > Chlorophyll > Calvin Cycle C. NADPH > Electron transport chain > O2 D. NADPH > O2 > CO2 E. H20 > Photosystem 1 > Photosystem 2
H2O > NADPH > Calvin Cycle
From the following choices, identify those that are the inputs and outputs of the light reactions. (Recall that inputs to chemical reactions are modified over the course of the reaction as they are converted into products. In other words, if something is required for a reaction to occur, and it does not remain in its original form when the reaction is complete, it is an input.)
Input: light, water, NADP+, ADP Output: O2, ATP, NADPH not input or output: glucose, CO2,G3P
From the following choices, identify those that are the inputs and outputs of the Calvin cycle.
Input:ATP, NADPH, CO2 Output:ADP, NADP+, G3P not input or output: light, glucose, O2 In the Calvin cycle, the energy outputs from the light reactions (ATP and NADPH) are used to power the conversion of CO2 into the sugar G3P. As ATP and NADPH are used, they produce ADP and NADP+, respectively, which are returned to the light reactions so that more ATP and NADPH can be formed.n the light reactions, light energy is used to oxidize H2O to O2.
The Calvin cycle oxidizes the light-reactions product NADPH to __________
NADP+
The __________ produced by photosystem I is used to supply energy for the production of sugars during photosynthesis.
NADPH
Which of the following products of the light reactions of photosynthesis is consumed during the Calvin cycle?
NADPH
The electrons derived from the oxidation reaction in the light reactions are used to reduce NADP+ to _________
NADPH.
Which of the following molecules is the primary product of photosystem I?
Nadph
Why are plants classified as producers?
Plants are classified as producers because they fix inorganic carbon into organic molecules.
Select the most accurate statement describing the basic function of the light reactions of photosynthesis.
The basic function of the light reactions of photosynthesis is the conversion of solar energy to chemical energy.
Which set of reactions uses H2O and produces O2? a) light independent reactions b) light dependent reactions
The light-dependent reactions
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 the light-independent reactions to form sugars
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. i.e plants
The rate of O2 production by the light reactions varies with the intensity of light because light is required as the energy source for O2 formation. Thus, lower light levels generally mean a lower rate of O2 production. In addition, lower light levels also affect the rate of CO2 uptake by the Calvin cycle. This is because the Calvin cycle needs the ATP and NADPH produced by the light reactions. In this way, the Calvin cycle depends on the light reactions. But is the inverse true as well? Do the light reactions depend on the Calvin cycle? Suppose that the concentration of CO2 available for the Calvin cycle decreased by 50% (because the stomata closed to conserve water). Which statement correctly describes how O2 production would be affected? (Assume that the light intensity does not change.)
The rate of O2 production would decrease because the rate of ADP and NADP+ production by the Calvin cycle would decrease
True or false? The light-dependent reactions of photosynthesis use water and produce oxygen.
True
During the Calvin cycle electrons stored in NADPH are used to reduce ________________
carbon
An elaborate system of interconnected thylakoid membranes segregates the stroma from the thylakoid space in the ___________
chloroplast.
in the light reactions, light energy is used to oxidize H2O to _______.
o2
Photosynthesis is a redox reaction. This means that H2O is _____ during the light reactions and CO2 is _____ during the Calvin cycle
oxidized and reduced
Which of the following is a product of the light reactions of photosynthesis?
oxygen, ATP, and NADPH
In the electromagnetic spectrum, the type of radiation that we call visible light occurs between
ultraviolet radiation and infrared radiation
The light reactions of photosynthesis use _____ and produce _____.
water to produce nadph
_____ has a longer wavelength than _____. - Yellow ... red - Blue ... green - Green ... yellow - Red ... green - Violet ... blue
Red.... green
Which molecule is regenerated in the regeneration phase of the Calvin cycle? Without regeneration of this molecule, the Calvin cycle would stop.
Regeneration of RuBP
Which of the following does not occur during the Calvin cycle? Carbon fixation Release of oxygen Oxidation of NADPH Regeneration of the CO2 acceptor Consumption of ATP
Release of oxygen
The regeneration of _________ ensures that the Calvin cycle can proceed indefinitely, since it fixes carbon dioxide into an organic molecule that is used to produce sugar.
RuBP
The net reaction of the Calvin cycle is the conversion of CO2 into the three-carbon sugar G3P. Along the way, reactions rearrange carbon atoms among intermediate compounds and use the ATP and NADPH produced by the light reactions. In this exercise, you will track carbon atoms through the Calvin cycle as required for the net production of one molecule of G3P. For each intermediate compound in the Calvin cycle, identify the number of molecules of that intermediate and the total number of carbon atoms contained in those molecules. As an example, the output G3P is labeled for you: 1 molecule with a total of 3 carbon atoms. Labels may be used once, more than once, or not at all.
The Calvin cycle requires a total of 9 ATP and 6 NADPH molecules per G3P output from the cycle (per 3 CO2 fixed). In Phase 2, six of the ATP and all of the NADPH are used in Phase 2 to convert 6 molecules of PGA to 6 molecules of G3P. Six phosphate groups are also released in Phase 2 (derived from the 6 ATP used). In the first part of Phase 3, 5 molecules of G3P (1 phosphate group each) are converted to 3 molecules of R5P (also 1 phosphate group each). Thus there is a net release of 2 Pi. In the second part of Phase 3, 3 ATP molecules are used to convert the 3 R5P into 3 RuBP. Note that in the entire cycle, 9 ATP are hydrolyzed to ADP; 8 of the 9 phosphate groups are released as Pi, and the ninth phosphate appears in the G3P output from the cycle.
What is the biological significance of the light-independent reactions of photosynthesis?
They convert carbon dioxide to sugar (All organisms use the sugars produced by photosynthesis to generate energy)
Identify the stroma.
E (space between thylakoid and membrane)
In eukaryotes, all the reactions of photosynthesis occur in various membranes and compartments of the chloroplast. Identify the membranes or compartments of the chloroplast by dragging the blue labels to the blue targets. Then, identify where the light reactions and Calvin cycle occur by dragging the pink labels to the pink targets.
a) stroma-the dense fluid surrounded between the inner envelope membrane and the thylakoid membranes b) thylakoid membrane-the third membrane system; surrounds the thylakoid; chrorophyll resides in the thylakoid membrane c)cytosol-the fluid portion of cytoplasm surrounding (outside) the chloroplast d) location of Calvin Cycle-the calvin cycle occurs in the stroma e) thylakoid space-the space within the thylakoid sacs f)location of light reactions-the light reactions occur in the thylakoids of the chloroplast g) envelope membranes-the inner and outer membranes of the chloroplast The chloroplast is enclosed by a pair of envelope membranes (inner and outer) that separate the interior of the chloroplast from the surrounding cytosol of the cell. Inside the chloroplast, the chlorophyll-containing thylakoid membranes are the site of the light reactions. Between the inner envelope membrane and the thylakoid membranes is the aqueous stroma, which is the location of the reactions of the Calvin cycle. Inside the thylakoid membranes is the thylakoid space, where protons accumulate during ATP synthesis in the light reactions.
When light strikes chlorophyll molecules, they lose electrons, which are ultimately replaced by _____
splitting water The electrons removed from water are transferred to P680.
The Calvin cycle occurs in the
stroma
