BIO 101: Chapter 8

In mechanism, photophosphorylation is most similar to __________. substrate-level phosphorylation in glycolysis carbon fixation oxidative phosphorylation in cellular respiration reduction of NADP+ the Calvin cycle

oxidative phosphorylation in cellular respiration

_____ has a longer wavelength than _____. Yellow ... red Green ... yellow Violet ... blue Red ... green Blue ... green

Red ... green

Leaves appear green because

chlorophyll reflects and transmits green light and thus green light is not used for photosynthesis.

Which set of reactions uses H2O and produces O2? light dependent reactions light independent reactions

light dependent reactions

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? Protons will not diffuse toward the outside of the vesicles. ATP will not be produced because there is no ADP and inorganic phosphate in the solution. ATP will be produced because the proton gradient favors proton movement through the ATP synthase channels. The change in the solution's pH results in a gradient across the chloroplast membranes such that there is a lower concentration of protons inside the vesicles and a higher concentration outside.

ATP will not be produced because there is no ADP and inorganic phosphate in the solution.

Identify a thylakoid.

D

Identify the stroma.

E

Where does the Calvin cycle occur?

E-stroma

Which of these phosphorylates ADP to make ATP?

E. ATP synthase phosphorylates ADP.

Photosynthesis is a redox process in which

H2O is oxidized and CO2 is reduced -Photosynthesis is an endergonic process. Sunlight provides the energy required to power this

Which of the following sequences correctly represents the flow of electrons during photosynthesis? NADPH → chlorophyll → Calvin cycle H2O → NADPH → Calvin cycle NADPH → electron transport chain → O2 H2O → photosystem I → photosystem II NADPH → O2 → CO2

H2O → NADPH → Calvin cycle

Which of the following sequences correctly represents the flow of electrons during photosynthesis? NADPH → electron transport chain → O2 NADPH → O2O2 → CO2 H2O → NADPH → Calvin cycle NADPH → chlorophyll → Calvin cycle H2O → photosystem I → photosystem II

H2O → NADPH → Calvin cycle

How is photosynthesis similar in C4C4 plants and CAM plants? a. In both cases, only photosystem I is used. b. Both types of plants make sugar without the Calvin cycle. c. In both cases, rubisco is not fixed to carbon initially. d. Both types of plants make most of their sugar in the dark. e. In both cases, thylakoids are not involved in photosynthesis.

In both cases, rubisco is not used to fix carbon initially.

CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they

fix CO2 into organic acids during the night.

You could distinguish a granum from a crista because the granum, but not the crista, would __________. have photosynthetic pigments function in energy transformation contain protein but not lipids All of the listed responses are correct. be inside a mitochondrion

have photosynthetic pigments

electromagnetic radiation

light is a form of electromagnetic energy aka electromagnetic radiation

stomata

microscopic pores where CO2 enters and O2 exits the leaf

heterotroph

organism that obtains energy from the foods it consumes; also called a consumer -Almost all heterotrophs depend directly or indirectly on photoautotrophs for food and O2

In mechanism, photophosphorylation is most similar to __________. carbon fixation oxidative phosphorylation in cellular respiration reduction of NADP+ substrate-level phosphorylation in glycolysis the Calvin cycle

oxidative phosphorylation in cellular respiration

In mechanism, photophosphorylation is most similar to __________. oxidative phosphorylation in cellular respiration reduction of NADP+ carbon fixation the Calvin cycle substrate-level phosphorylation in glycolysis

oxidative phosphorylation in cellular respiration

Which of the following are directly associated with photosystem I? extraction of hydrogen electrons from the splitting of water generation of molecular oxygen passing electrons to the thylakoid membrane electron transport chain harvesting of light energy by ATP receiving electrons from the thylakoid membrane electron transport chain

passing electrons to the thylakoid membrane electron transport chain

Which of the following terms refers to organisms that sustain themselves in the ecosystem by transferring light energy from the sun to chemical energy stored in the bonds of sugar molecules? chemoautotrophs photoautotrophs heterotrophs

photoautotrophs

In C3 plants the conservation of water promotes _____. photosynthesis a shift to C4 photosynthesis the light reactions the opening of stomata photorespiration

photosynthesis

Which of the following does NOT occur during the Calvin cycle? carbon fixation regeneration of the CO2 acceptor oxidation of NADPH release of oxygen consumption of ATP

release of oxygen

When oxygen is released as a result of photosynthesis, it is a direct by-product of: chemiosmosis. the electron transfer system of photosystem I. reducing NADP+. splitting water molecules. the electron transfer system of photosystem II.

splitting water molecules.

The Calvin cycle occurs in the __________. thylakoid space stroma thylakoid membrane matrix stomata

stroma

Where does the Calvin cycle take place?

stroma of the chloroplast

Pigments

substances that absorb visible light -Different pigments absorb different wavelengths -Wavelengths that are not absorbed are reflected or transmitted

In C3 photosynthesis, the reactions that require ATP take place in

the Calvin cycle alone.

Wavelength

the distance between crests of waves -Like other electromagnetic energy, light travels in rhythmic waves -Wavelength determines the type of electromagnetic energy

Rubisco is __________. the enzyme in C3 plants that first captures CO2 to begin the Calvin cycle the enzyme responsible for splitting H2O to produce O2 in photosynthesis the first stable intermediate in C4 photosynthesis the enzyme that forms a 4-carbon compound in CAM photosynthesis the 5-carbon sugar molecule that reacts with CO2 to begin the Calvin cycle

the enzyme in C3 plants that first captures CO2 to begin the Calvin cycle

Photosynthesis

the process that converts solar energy into chemical energy

When chloroplast pigments absorb light, __________. their photons become excited the Calvin cycle is completed they lose potential energy they become reduced

their electrons become excited

During photosynthesis in a eukaryotic cell, an electrochemical gradient is formed across the ___________. stomata thylakoid membrane chloroplast inner membrane cristae chloroplast outer membrane

thylakoid membrane

The source of the oxygen produced by photosynthesis has been identified through experiments using radioactive tracers. The oxygen comes from __________. radioisotopes water glucose light carbon dioxide

water

Which of the following molecules is the primary product of photosystem I? NADPH O2 ATP CO2

NADPH

What does the chemiosmotic process in chloroplasts involve?

establishment of a proton gradient across the thylakoid membrane

Various photosynthetic pigments are:

-Chlorophyll a is the main photosynthetic pigment -Chlorophyll b is an accessory pigments and it broadens the spectrum used for photosynthesis -Accessory pigments called carotenoids absorb excessive light that would damage chlorophyll

A Comparison of Chemiosmosis in Chloroplasts and Mitochondria:

-Chloroplasts and mitochondria generate ATP by chemiosmosis but use different sources of energy -Mitochondria transfer chemical energy from food to ATP; chloroplasts transform light energy into the chemical energy of ATP -Both use energy generated by an electron transport chain to create a proton (H+) gradient across a membrane. -Both rely on the diffusion of protons through ATP synthase to drive synthesis of ATP -In mitochondria, protons are pumped to the intermembrane space and drive ATP synthesis as they diffuse back into the mitochondrial matrix -In chloroplasts, protons are pumped into the thylakoid space and drive ATP synthesis as they diffuse back into the stroma

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle? ADP, i, and NADP+ electrons and H+ H2O and O2 CO2 and glucose ATP and NADPH

ATP and NADPH

Chloroplasts

-are found mainly in cells of the mesophyll, region in the interior tissue of the leaf -site of photosynthesis -solar-powered chemical factories -Each mesophyll cell contains 30-40 chloroplasts

Visible light

-consists of the wavelengths from 380 nm to 750 nm and can be detected as colors by the human eye -Photosynthesis is powered by visible light

light-harvesting complexes transfer the

-energy of photons to the reaction center

Linear Electron Flow steps:

1. A photon hits a pigment in the light-harvesting complex of PSII and its energy is passed among pigment molecules until it reaches P680 2. An excited electron from P680 is transferred to the primary electron acceptor (we now call it P680+) 3. H2O is split; two electrons reduce to P680, two are released into the thylakoid space, and oxygen atoms combine to form O2 4. Electrons are passed down an electron transport chain from PS II to PS I, releasing energy used to form a proton gradient across the thylakoid membrane 5.Potential energy from the proton gradient is used to power chemiosmosis and the production of ATP 6. In PS I, energy from a photon reaches P700, which transfers an electron to the primary electron acceptor-P700+ accepts an electron from P S II via the electron transport chain 7. Electrons are passed down an electron transport chain from the primary electron acceptor of PS I to the protein ferredoxin (Fd) 8. NADP+ reductase catalyzes the transfer of electrons and H+ to NADP+; NADPH carries electrons to the reactions of the Calvin cycle

In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?

3

_____ splits water into 1/2 O2, H+, and e- .

A. Photosystem II splits water into 1/2 O2, H+, and e- .

How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?

6

Which of these equations best summarizes photosynthesis? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy 6 CO2 + 6 H2O → C6H12O6 + 6 O2 H2O → 2 H+ + 1/2 O2 + 2e- 6 CO2 + 6 O2 → C6H12O6 + 6 H2O C6H12O6 + 6 O2 → 6 CO2 + 12 H2O

6 CO2 + 6 H2O → C6H12O6 + 6 O2

Identify the chloroplast.

A

Chlorophyll can be found in _____.

A and C. The photosystems contain chlorophyll.

The light reactions of photosynthesis supply the Calvin cycle with __________. H2O and NADPH light energy CO2 and ATP sugar and O2 ATP and NADPH

ATP and NADPH

What are the products of linear electron flow?

ATP and NADPH

Glyceraldehyde-3-phosphate (G3P) is produced in the stroma of chloroplasts. Which of the following statements about this compound is most true? It is a three-carbon sugar. For every three molecules of CO2, six molecules of G3P are formed but five molecules must be recycled to regenerate three molecules of RuBP. All of the listed responses are correct. For every three molecules of CO2, six molecules of G3P are formed but only one molecule exits the cycle to be used by the plant cell. It is produced from glucose during glycolysis.

All of the listed responses are correct.

autotroph

An organism that makes its own food -"self-feeders"; they get energy and carbon entirely from nonliving sources -All plants that do photosynthesis are autotrophs

Which of the following statements is a correct distinction between autotrophs and heterotrophs? Only heterotrophs require oxygen. Cellular respiration is unique to heterotrophs. Only heterotrophs require chemical compounds from the environment. Only heterotrophs have mitochondria. Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.

Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.

What portion of the electromagnetic spectrum is most absorbed by the chlorophyll pigments in the thylakoid membranes? Blue-violet and red light The same range absorbed by carotenoids The entire spectrum of white light The infrared Green, which is why plants are green

Blue-violet and red light

What portion of the electromagnetic spectrum is most absorbed by the chlorophyll pigments in the thylakoid membranes? The entire spectrum of white light The infrared Blue-violet and red light The same range absorbed by carotenoids Green, which is why plants are green

Blue-violet and red light

ATP synthesis in chloroplasts is very similar to that in mitochondria: Electron transport is coupled to the formation of a proton (H+) gradient across a membrane. The energy in this proton gradient is then used to power ATP synthesis. Two types of processes that contribute to the formation of the proton gradient are: processes that release H+ from compounds that contain hydrogen, and processes that transport H+ across the thylakoid membrane. Drag the labels to the appropriate locations on the diagram of the thylakoid membrane.

Bottom Left Red Box: Site of H+ release First Blue Box: H+ pumped across membrane Third/Last Blue Box: H+ diffuse across membrane Last red box (at the top right) :site of ATP synthesis

Energized electrons from ____ are used to reduce NADP+.

C. Energized electrons from photosystem I are used to reduce NADP+.

What is the basic role of CO2 in photosynthesis? CO2 is a source of electrons in the formation of organic molecules. CO2 is fixed or incorporated into organic molecules. CO2 is taken in by plants as a form of inverse respiration, in which carbon dioxide is "breathed in" and oxygen is "breathed out."

CO2 is fixed or incorporated into organic molecules.

Step 2 of photosynthesis:

Carbon from CO2 of air and 'H' from water that got split are fixed together to give sugar. -The direct product of photosynthesis is not glucose. But a three-carbon simple sugar that is used further to make glucose ( a six-carbon sugar).

Select the correct molecule that is the main product of the Calvin cycle.

G3P

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.

F

True or false? The region of ATP synthase that catalyzes the production of ATP from ADP and inorganic phosphate spans the chloroplast membrane.

F

From the following choices, identify those that are the inputs and outputs of the Calvin cycle. Drag each item to the appropriate bin. If the item is not an input to or an output from the Calvin cycle, drag it to the "not input or output" bin.

Input: NADPH ATP CO2 Output: ADP NADP+ G3P Not Input or Output: O2 Glucose Light

Choose light reactions or Calvin cycle: Produces oxygen Produces sugar Split water. Uses carbon dioxide as a source of carbon. Produces ATP and NADPH. Uses chlorophyll molecules to absorb energy from the sun.

Light reactions Calvin cycle Light reactions Calvin cycle Light reactions Light reactions

In 1883, Theodor W. Engelmann conducted a classic experiment in which he illuminated a filament of photosynthetic algae with light that passed through a prism, thus exposing different segments of the algae to different wavelengths of light. He then added aerobic, nonphotosynthetic bacteria, and noted that the largest groups of bacteria were found in the areas illuminated by the red and blue light. Using what you know about photosynthesis and cellular respiration, which of the following would best explain the reason for the bacteria congregating in the regions with red and blue light?

More bacteria congregated in the red and blue light regions because the algae in those regions produced the most oxygen. Submit

After 3-PGA is phosphorylated, it is reduced by _____. CO2 NADPH ADP NADP+ ATP

NADPH

What compound provides the reducing power for the Calvin cycle reactions?

NADPH

In the parts of the investigation that follow, we conduct experiments using leaf disk samples to test whether they are undergoing photosynthesis based on whether they float in solution. What gives the leaf disks their buoyancy?

Oxygen accumulating in the air spaces within the mesophyll.

Which term describes ATP production resulting from the capture of light energy by chlorophyll? Dephosphorylation Photophosphorylation Substrate-level phosphorylation Oxidative phosphorylation

Photophosphorylation

Which of the following statements best describes the relationship between photosynthesis and respiration?

Photosynthesis stores energy in complex organic molecules, whereas respiration releases it.

Why are plants classified as producers? Plants are classified as producers because they fix inorganic carbon into organic molecules. Plants are classified as producers because they are at the bottom of the food chain. Plants are classified as producers because they produce oxygen.

Plants are classified as producers because they fix inorganic carbon into organic molecules.

Which of the following particles can pass through the ATP synthase channel? ATP Protons Inorganic phosphate ADP

Protons

How is photosynthesis similar in C4 plants and CAM plants? In both cases, only photosystem I is used. Rubisco in not the enzyme that catalyzes the initial fixation of carbon. In both cases, thylakoids are not involved in photosynthesis. Both types of plants make sugar without the Calvin cycle. Both types of plants make most of their sugar in the dark.

Rubisco in not the enzyme that catalyzes the initial fixation of carbon.

the first step of the light reactions

Solar-powered transfer of an electron from a chlorophyll a molecule to the primary electron acceptor

T/F: If higher the oxygen column is produced then more photosynthesis is taking place.

T

T/F: Oxygen is released at the end of the photosynthesis.

T

True or false? The light-dependent reactions of photosynthesis use water and produce oxygen.

T

Which statement describes the functioning of photosystem II? The electron vacancies in P680+ are filled by electrons derived from water. The P680 chlorophyll donates a pair of protons to NADP+, which is thus converted to NADPH. The splitting of water yields molecular carbon dioxide as a by-product. Photons are passed along to a reaction-center chlorophyll. Light energy excites electrons in the thylakoid membrane electron transport chain.

The electron vacancies in P680+ are filled by electrons derived from water.

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.

What is the importance of the light-independent reactions in terms of carbon flow in the biosphere? a. The light-independent reactions use CO2 to make ATP. b. The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars. c. The light-independent reactions turn sugar into ATP for energy. d. The light-independent reactions turn glucose, a sugar, into CO2 gas.

The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars.

What is the biological significance of the light-independent reactions of photosynthesis? They make oxygen. They generate ATP and NADPH. They convert ATP to sugar. They convert carbon dioxide to sugar.

They convert carbon dioxide to sugar.

Why are C4 plants able to photosynthesize with no apparent photorespiration?

They use PEP carboxylase to initially fix CO2.

How does carbon dioxide enter the leaf? Through the stomata Through the roots Through the thylakoids Through the vascular system Through the chloroplasts

Through the stomata

Why are C4 plants more suited to hot climates than C3 plants? The same cells that bind carbon dioxide perform the Calvin cycle. They do not close their stomata in hot, dry weather. They suspend photosynthesis during the hottest part of the day. Unlike C3 plants, they keep fixing carbon dioxide even when the concentration of carbon dioxide in the leaf is low. They are an older lineage and have had longer to adapt.

Unlike C3 plants, they keep fixing carbon dioxide even when the concentration of carbon dioxide in the leaf is low.

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 b) thylakoid membrane c) cytosol d) location of Calvin Cycle e) thylakoid space f)location of light reactions g) envelope membranes

The Calvin cycle depends on inputs of chemical energy (ATP) and reductant (NADPH) from the light reactions to power the conversion of CO2 into G3P. In this exercise, consider the net conversion of 3 molecules of CO2 into 1 molecule of G3P. Drag the labels to the appropriate targets to indicate the numbers of molecules of ATP/ADP, NADPH/NADP+, and Pi (inorganic phosphate groups) that are input to or output from the Calvin cycle.

a. 6 ATP 6 ADP b. 6 NADPH 6 NADP+ c. 6pi d. 2pi e. 3 ADP 3 ATP

Select the correct statement about the Calvin cycle. a. The Calvin cycle has three phases: carbon fixation, reduction, and regeneration of RuBP. b. The Calvin cycle takes place primarily in the dark. c. The basic function of the Calvin cycle is the conversion of solar energy to chemical energy.

a. The Calvin cycle has three phases: carbon fixation, reduction, and regeneration of RuBP.

The phylogenetic distribution of the enzyme rubisco is limited to

all known photoautotrophs, both bacterial and eukaryotic.

A photon of which of these colors of light would carry the most energy? Green Yellow Blue Red Orange

blue

In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during

both photosynthesis and respiration.

decomposers

break down and absorb energy and nutrients from nonliving remains or wastes of other organisms

In C4 and CAM plants carbon dioxide is fixed in the _____ of mesophyll cells. stroma stomata thylakoids cytoplasm grana

cytoplasm

During photosynthesis, an electron transport chain transports __________. excited electrons from P680 to an electron acceptor excited electrons from P700 to an electron acceptor NADPH from the light reactions to the Calvin cycle electrons from photosystem II to photosystem I excited electrons from P700 to an electron acceptor and transport excited electrons from P680 to an electron acceptor

electrons from photosystem II to photosystem I

The light reactions (in the thylakoids):

-Split H2O -Release O2 -Reduce the electron acceptor, NADP+, to NADPH -Generate ATP from ADP by adding a phosphate group, photophosphorylation

two types of photosystems in the thylakoid membrane

-Photosystem II (PS II) functions first (the numbers reflect order of discovery) and is best at absorbing a wavelength of 680 nm -Photosystem I (PS I) is best at absorbing a wavelength of 700 nm

The light reactions require the cooperation of two photosystems to power linear electron flow from water to NADP+. Drag each item into the appropriate bin depending on whether the process is associated with Photosystem II (PS II) only, Photosystem I (PS I) only, or both PS II and PS I. Note that "electron transport chain" here refers to the electron transport chain between the two photosystems, not the one that functions after PS I.

-Photosystem II: oxidation of water reduction of electron transport chain between the two photosystems - Photosystem I: reduction of NADP+ oxidation of electron transport chain between the two photosystems - Both: light absorption reduction of primary electron acceptor

photoautotrophs

-Plants use sunlight or solar energy for this process hence are called photoautotrophs -Plants are producers that make organic molecules using CO2 from air and inorganic nutrients from soil

thylakoids

-the chlorophyll is in the membranes -connected sacs in the chloroplast -may be stacked in columns called grana / granum. -transform light energy into the chemical energy of ATP and NADPH

For each step of photosynthetic electron flow from water to NADP+, drag the appropriate label to indicate whether or not that step requires an input of energy. 1) Water to P680+ 2) P680 to Pq (plastoquinone) 3) Pq to P700+ 4) P700 to Fd (ferredoxin) 5) Fd to NADP+

1) Water to P680+: No energy input required 2) P680 to Pq (plastoquinone): Energy input required 3) Pq to P700+: No energy input required 4) P700 to Fd (ferredoxin): Energy input required 5) Fd to NADP+: No energy input required

In photosynthesis, a redox compound that is produced in the light reactions is required to drive other redox reactions in the Calvin cycle, as shown in this figure along with other components of photosynthesis. Drag the terms to the appropriate blanks to complete the following sentences summarizing the redox reactions of photosynthesis. Terms may be used once, more than once, or not at all. 1. In the light reactions, light energy is used to oxidize ______ to _______. 2. The electrons derived from this oxidation reaction in the light reactions are used to reduce _______ to _______. 3. The Calvin cycle oxidizes the light-reactions product ______ to ______. 4. The electrons derived from this oxidation reaction in the Calvin cycle are used to reduce _____ to _____.

1. In the light reactions, light energy is used to oxidize H2O to O2. 2. The electrons derived from this oxidation reaction in the light reactions are used to reduce NADP+ to NADPH. 3. The Calvin cycle oxidizes the light-reactions product NADPH to NADP+. 4. The electrons derived from this oxidation reaction in the Calvin cycle are used to reduce CO2 to G3P.

_____ releases energy that is used to pump hydrogen ions from the stroma into the thylakoid compartment.

B. The energy released as electrons are passed along the electron transport chain is used to pump protons into the thylakoid compartment.

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.) Drag each item to the appropriate bin. If the item is not an input to or an output from the light reactions, drag it to the "not input or output" bin.

Input: NADP+ ADP water light Output: ATP NADPH O2 Not Input or Output: CO2 G3P glucose

What is the role of NADP+ in photosynthesis? It is reduced and then carries electrons to the Calvin cycle. It is the pigment that captures light energy. It donates electrons to the electron transport chain linking photosystems II and I. It replaces the electrons donated by P680. As part of the process of chemiosmosis, it manufactures ATP.

It is reduced and then carries electrons to the Calvin cycle.

According to the chemiosmotic hypothesis, what provides the energy that directly drives ATP synthesis? Temperature gradient Osmotic gradient Proton gradient Electrons

Proton gradient

Which of the following does not occur during the Calvin cycle? Regeneration of the CO2 acceptor Consumption of ATP Release of oxygen Carbon fixation Oxidation of NADPH

Release of oxygen

Which process is most directly driven by light energy? Carbon fixation in the stroma ATP synthesis Reduction of NADP+ molecules Creation of a pH gradient by pumping protons across the thylakoid membrane Removal of electrons from chlorophyll molecules

Removal of electrons from chlorophyll molecules

Carbon fixation involves the addition of carbon dioxide to _____. NADPH Rubisco RuBP 3-PGA G3P

RuBP

Which molecule is regenerated in the regeneration phase of the Calvin cycle? Without regeneration of this molecule, the Calvin cycle would stop. 3-phosphoglycerate RuBP G3P ATP

RuBP

Step 1 of photosynthesis:

Splitting of Water to hydrogen (H) and oxygen. -Oxygen is released as gas.

The reactions of the Calvin cycle are not directly dependent on light, but they usually do not occur at night. Why? Plants usually open their stomata at night. Carbon dioxide concentrations decrease at night. The Calvin cycle requires products only produced when the photosystems are illuminated. At night, no water is available for the Calvin cycle. It is often too cold at night for these reactions to take place.

The Calvin cycle requires products only produced when the photosystems are illuminated.

Which of the following statements correctly describes the relationship between the light reactions and the Calvin cycle? The light reactions produce carbon dioxide and water, both of which are used in the Calvin cycle. The light reactions produce ADP and NADP+, both of which are used in the Calvin cycle. The light reactions produce carbon dioxide, ATP, and NADPH, all of which are used in the Calvin cycle. The light reactions produce water, ATP, and NADPH, all of which are used in the Calvin cycle. The light reactions produce ATP and NADPH, both of which are used in the Calvin cycle.

The light reactions produce ATP and NADPH, both of which are used in the Calvin cycle.

Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis? a. The light-independent reactions release energy, and the light-dependent reactions require energy. b. The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions. c. The light-dependent reactions pass electrons through an electron transport chain to the light-independent reactions. d. The light-dependent reactions produce carbon dioxide, which is then used by the light-independent reactions. Submit

The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions.

Chlorophyll molecules are in which part of the chloroplast? Plasma membrane Stroma Stomata Thylakoid membranes Thylakoid space

Thylakoid membranes

Chloroplasts also contain stroma

a dense interior fluid

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.

a. 3 molecules 3 carbons b. 6 molecules 18 carbons c. 6 molecules 18 carbons d. 5 molecules 15 carbons e. 3 molecules 15 carbons f. 3 molecules 15 carbons

Drag the labels from the left to their correct locations in the concept map on the right. Not all labels will be used.

a. sunlight b. photosynthesis c. chloroplasts d. sugar e. chlorophyll f. carbon dioxide g. cellular respiration h. mitochondria

C4 plants differ from C3 and CAM plants in that C4 plants _____. a. are better adapted to wet conditions b. use malic acid to transfer carbon dioxide to the Calvin cycle c. transfer fixed carbon dioxide to cells in which the Calvin cycle occurs d. use PEP carboxylase to fix carbon dioxide e. open their stomata only at night

c

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.) a. The rate of O2 production would decrease because the rate of G3P production by the Calvin cycle would decrease. b. The rate of O2 production would remain the same because the light reactions are independent of the Calvin cycle. c. The rate of O2 production would decrease because the rate of ADP and NADP+ production by the Calvin cycle would decrease. d. The rate of O2 production would remain the same because the light intensity did not change.

c. The rate of O2 production would decrease because the rate of ADP and NADP+ production by the Calvin cycle would decrease.

The most important role of pigments in photosynthesis is to __________. capture light energy catalyze the synthesis of ATP absorb heat energy catalyze the hydrolysis of water store energy

capture light energy

In photosynthesis, plants use carbon from __________ to make sugar and other organic molecules. soil the sun chlorophyll carbon dioxide water

carbon dioxide

Photons have a fixed quantity of energy which is

inversely proportional to the wavelength of light. -The shorter the wavelength of light, the greater the energy per photon

Linear electron flow

involves the flow of electrons through the photosystems and other molecules embedded in the thylakoid membrane to produce ATP and NADPH using light energy

Which process produces oxygen? photosynthesis cellular respiration

photosynthesis

light-harvesting complexes

pigment molecules bound to protein

photosystem consists of a

reaction-center complex (a type of protein complex) surrounded by light-harvesting complexes

Where do the electrons entering photosystem II come from? The electron transport chain Water Light Chlorophyll molecules in the antenna complex ATP

water

The light reactions of photosynthesis use _____ and produce _____. carbon dioxide ... sugar water ... NADPH carbon dioxide ... oxygen NADPH ... NADP+ NADPH ... oxygen

water...NADPH