Category - Definitions

Query - What definition best describes the term below?

Reversal

Category - Term Recognition

Query - What term does the description below refer to?

(Terms are shown on left, descriptions in middle, figures on right)

Antenna Pigment Molecules | A series of molecules through which captured energy (in the form of an excited electron) from a photon of light may "wander" before arriving at a reaction center. Most chlorophylls act as antenna molecules. | Figure 17.11 | Bacteriochlorophyll b | A type of chlorophyll found in photosynthetic bacteria. |  | Calvin Cycle | The series of reactions in the dark cycle of photosynthesis in which carbon dioxide is fixed by adding one molecule at a time to an acceptor molecule and passing the molecule through a series of reactions. |  | Chloroplast | Plant and algae organelle where photosynthesis occurs. |  | Chromophores | Photosynthetic pigments that absorb specific wavelengths of light for photosynthesis. | Figure 17.8 | Cyclic Electron Flow | An alternative pathway of electron flow (compared to noncyclic electron flow), which utilizes the components of photosystem I, plus plastocyanin and the cytochrome bf complex. | Figure 17.17 | Dark Reactions of Photosynthesis | The second step of photosynthesis in which NADPH and ATP produced by the light reactions is used in reductive synthesis of carbohydrate from CO2 and water. | Figure 17.3 | Einstein | A unit for a mole of photons |  | Electron Transfer | A process where an electron, excited by light in photosynthesis, is passed to a nearby molecule with a slightly lower excited state. | Figure 17.11 | Granum (grana) | A chloroplast structure consisting of a stack of thylakoids. | Figure 17.4c | Hill Reactions | Reactions pioneered by Robert Hill that showed when isolated chloroplasts were illuminated in the presence of electron acceptors, such as Fe3+, the acceptor could be reduced. |  | Inner Chloroplast Membrane | A structure analogous to the mitochondrial inner membrane which is quite selectively permeable to molecules. | Figure 17.4c | Light Reactions of Photosynthesis | The first step of photosynthesis in which energy from light is used to drive photochemical oxidation of H2O. This produces NADPH, releases O2, and ADP is phosphorylated to ATP. | Figure 17.3 | Light-harvesting Complexes | Part of the photosynthetic apparatus. Each is a multisubunit protein complex containing multiple antenna pigment molecules and a pair of chlorophyll molecules that act as the reaction center, trapping energy quanta excited by the absorption of light. | Figure 17.10 | Noncyclic Electron Flow | In a two-system transfer of electron energy, the process where electrons displaced from photosystem I by excitation are replaced by photosystem II, which receives them from water. |  | Noncyclic Photophosphorylation | The generation of ATP by noncyclic electron flow. |  | Outer Chloroplast Membrane | A structure analogous to the mitochondrial outer membrane which is quite freely permeable to most molecules. | Figure 17.4c | Photophosphorylation | A term for the process whereby ATP is synthesized as a result of energy captured from light. |  | Photorespiration | A pathway favored when the oxygenase activity of ribulose-1,5-bisphosphate carboxylase is active. In it, phosphoglycolate is dephosphorylated and passed into the peroxisomes where it is oxidized to hydrogen peroxide and glyoxylate. | Figure 17.24 | Photosynthesis | A process whereby energy from light is harvested and used to drive synthesis of carbohydrates from carbon dioxide and water (usually). | Figure 17.1 | Photosystem I | A photosystem in plants that absorbs light up to a wavelength of about 700 nm. A product of electron transfer through this photosystem is reduction of NADP+ to form NADPH. | Figure 17.12, Figure 17.14 | Photosystem II | A photosystem in plants that absorbs light only up to a wavelength of about 680 nm. It is the photosystem associated with the initial excitation of electrons, the splitting of water to form O2, and the pumping of protons from the stroma into the thylakoid | Figure 17.12 | Photosystems | Well-defined structural units of chloroplasts dedicated to the task of absorbing light photons and recovering some of their energy in a chemical form. |  | Planck's Law | A basic equation in physics that relates the energy per photon to the frequency of light - E = hv, where h is Planck's constant, 6.626 x 10-34 J s. |  | Quantum | A single unit of light energy |  | Quantum Efficiency (of photosynthesis) | The ratio of oxygen molecules released to photons absorbed. |  | Reaction Center | Part of the photosyntetic apparatus where the excited electron from light stimulation is transferred to a primary electron acceptor. The chlorophyll here is in a somewhat different environment than other chlorophylls, so that its excited state energy level is a bit lower, allowing it to trap the quanta of energy absorbed by any other pigment molecules. | Figure 17.11 | Red Drop | A phenomenon observed where the quantum efficiency for a compound dropped as the wavelength of monochromatic light used was raised above 680 nm. |  | Reduction | A process involving the gain of electrons by a molecule. |  | Resonance Transfer (Exciton Transfer) | A process where energy from light in photosynthesis, is passed from one molecule to another. | Figure 17.11 | Rhodopseudomonas viridis | A purple sulfur bacterium that conducts photosynthesis |  | Stroma | A chloroplast structure analogous to the mitochondrial matrix. It consists of the space between the grana and the inner mitochondrial membrane. The place where the dark reactions of photosynthesis occur. | Figure 17.4c | Thylakoid Lumen | The space inside the inner part of a thylakoid membrane | Figure 17.4c | Thylakoids | Flat, saclike membrane structures in the stroma of the chloroplast stacked like coins to form a granum. All of the light reactions of photosynthesis occur within the membranes of these structures. | Figure 17.4c | Z | An intermediate through which electrons from the splitting of water are passed to the oxidized photosystem II reaction center. It is likely a tyrosine residue on one of the polypeptide chains of photosystem II. |

Category - Molecules

Query - What molecule best fits the description below?

Reversal - there is no reversal

(molecule on left, description in center, figure on right)

1,3-Bisphosphoglycerate | Intermediate between 3-phosphoglycerate and glyceraldehyde-3-phosphate in Stage I of the Calvin cycle. | Figure 17.20 | 3-Phosphoglycerate | 3-carbon molecule produced directly after ribulose-1,5-bisphosphate binds CO2. | Figure 17.20 | Glyceraldehyde-3-phosphate | Three carbon molecule produced ultimately from 3-phosphoglycerate in the Calvin cycle. It is the branch point for making hexose phosphates and polysaccharides in the pathway. | Figure 17.20 | Ribulose-1,5-bisphosphate | Five carbon molecule to which carbon dioxide is bound in the Calvin cycle. | Figure 17.20 | ADP-Glucose | Activated form of glucose used to make amylose in plants. |  | Fructose-6-phosphate | An glycolytic intermediate in both stage II of the Calvin cycle and in synthesis of sucrose. |  | Glucose-1-phosphate | Combines with ATP to make ADP-glucose + PPi in plants. It also combines with UTP to make UDP-glucose + PPi. ADP-glucose is used to make amylose and UDP-glucose is used to make sucrose in plants. |  | Sucrose-6-phosphate | Disaccharide phosphate intermediate in synthesis of sucrose in plants. Produced as a result of a reaction between UDP-glucose and fructose-6-phosphate. |  | UDP-glucose | Activated form of glucose used in plants to make sucrose |

carotene | A precursor of vitamin A and an accessory photosynthetic pigment in plants | Figure 17.7

Phycocyanin | An accessory photosynthetic pigment in plants that is covalently attached to a protein via a sulfhydryl group. | Figure 17.7

Category - Structures

Query - What is the structure of the molecule below?

Reversal

Category - Molecules

Query - What is the name of the molecule with the structure below?

(Molecule on left, structure in middle, figures on right)

1,3-bisphosphoglycerate | Structure | Figure 17.20
3-Phosphoglycerate | Structure | Figure 17.20
Glyceraldehyde-3-phosphate | Structure | Figure 17.20
Ribulose-1,5-bisphosphate | Structure | Figure 17.20
ADP-Glucose | Structure |
Fructose-6-phosphate | Structure |
Glucose-1-phosphate | Structure |
Sucrose-6-phosphate | Structure |
UDP-glucose | Structure |

Category - Enzymes

Query - This description best matches which enzyme from Chapter 16?

Reversal

Category - General

Query - What function does the enzyme below have?

(Enzyme on left, description in center, figure on right)

Ferredoxin:NADP+ oxidoreductase | The enzyme catalyzes transfer of electrons to NADP+ from ferredoxin in photosystem I. The product is NADPH and oxidized ferredoxin. |

Category - General

Query - Is contained in the left column below, solution in middle, figure on right

Reversal - there is no reversal

(Questions on left, answers in center, figures on right)

In which direction are protons pumped in photosynthesis? | From the stroma into the thylakoid lumen. |  | In which photosystem are protons pumped from the stroma into the thylakoid lumen? | Photosystem II |  | What are the intermediates which contain five carbons in stage II of the Calvin cycle? | Ribose-5-phosphate, Xylulose-5-phosphate, Ribulose-5-phosphate, Ribulose-1,5-bisphosphate | Figure 17.22 | What is different about cyclic electron flow, compared to noncyclic electron flow? | No O2 is released by cyclic electron flow. No NADP+ is reduced by cyclic electron flow. |  | What energy classes of light does photosynthesis primarily depend upon? | Visible and near-infrared |  | Are chlorophylls a and b, the most common chlorophylls found in chloroplasts, covalently bound to proteins in the thylakoid membrane? | No |  | As the wavelength of light gets shorter, what happens to its energy? | Increases |  | From which organisms is it thought that chloroplasts are derived? | Cyanobacteria (blue-green algae) |  | How do photosynthetic pigments interact with thylakoid membrane lipids? | Through their hydrophobic phytol tails. | Figure 17.7a | How does light activate thioredoxin? | Electron transfer from the photosystem I produces reduced ferredoxin, which donates electrons to thioredoxin to reduce it. |  | How is ATP created as a result of electron transfers in the light reactions? | Pumping of protons into the thylakoid membrane during electron transport creates as a proton gradient. Dissipation of the gradient by passage through the CF0CF1 complex causes ADP + Pi to be converted to ATP. |  | How is water split by photosystem II? | The oxidized P680, after losing its electron by photo-induced excitement, stimulates the splitting of two molecules of water by an electron acceptor - a protein containing a cluster of four manganese atoms (called MnC). Electrons are passed through an intermediate called 'Z' to the oxidized P680 reaction center. Protons from the oxidized water are pumped into the thylakoid lumen and O2 is released. | Figure 17.13 | If 6 CO2 molecules are fixed in Stage I of the Calvin cycle, how many molecules of glyceraldehyde-3-phosphate will be produced? | 12 |  | In photosynthetic pigments, which electronic orbital does the electron, which is excited by light stimulation, reside in? | (Pi) |  | Name two crop species that have the C4 pathway. | Maize and sugar cane |  | What actually begins the photochemistry of the light reactions of photosynthesis? | Excitation of the reaction center of the light-harvesting complex. |  | What are the four-carbon intermediates in stage II of the Calvin cycle? | Erythrose-4-phosphate | Figure 17.22 | What are the reactions by which amylose is made in plants? | 1. Glucose-1-phosphate + ATP <=> ADP-glucose + PPi / 2. ADP-glucose + (glucose)n <=> (glucose)n+1 + ADP |  | What are the three enzymes of the Calvin cycle that are activated by a light-dependent reaction involving thioredoxin? | Sedoheptulose-1,7-bisphosphatase, Glyceraldehyde-3-phosphate-dehydrogenase, Ribulose-5-phosphate kinase | Figure 17.23 | What are the three-carbon intermediates in stage II of the Calvin cycle? | Glyceraldehyde-3-phosphate, Dihydroxyacetone phosphate (DHAP) | Figure 17.22 | What are the two eukaryotic organelles that contain DNA coding for some of their proteins? | Mitochondria and chloroplasts |  | What complex of the light cycle of photosynthesis is activated by a light-dependent mechanism involving thioredoxin? | The CF0-CF1 complex |  | What determines whether the noncyclic or cyclic electron flow system is used in photosynthesis? | Levels of NADP+. The cyclic process occurs when NADP+ levels are low. |  | What do C4 plants do differently from other (C3) plants? | They add a pathway where CO2 is incorporated into oxaloacetate (four carbons). |  | What energy sources does the Calvin cycle use? | ATP and NADPH |  | What enzyme catalyzes removal of a phosphate from a 7 carbon intermediate in stage II of the Calvin cycle? | Sedoheptulose-1,7-bisphosphatase | Figure 17.22 | What enzymes in stage II of the Calvin cycle catalyze "shuffling" of aldehyde and ketone groups necessary to regenerate the starting compounds? | Aldolases and ketolases | Figure 17.22 | What equation summarizes the overall reactions of the dark cycle? | 6CO2 + 18ATP + 12 NADPH + 12H2O -> C6H12O6 + 18 ADP + 18 Pi + 12 NADP+ + 6H+ |  | What is the additional energy cost of the C4 cycle? | Two high energy phosphate bonds per CO2 incorporated. (ATP is converted to AMP, which requires two phosphorylations to be converted back to ATP) | Figure 17.26 | What is the enzyme that incorporates CO2 into PEP to make oxaloacetate in C4 plants? | Phosphoenolpyruvate carboxylase | Figure 17.26 | What is the equation that relates the wavelength of light () to the frequency () | = c/, where c is the speed of light, 3 x 108 m/s. |  | What is the fate of the 12 molecules of glyceraldehyde-3-phosphate produced by binding of 6 CO2 molecules in the Calvin cycle? | Two are utilized to make a molecule of hexose. Ten are used to regenerate the 6 molecules of ribulose-1,5-bisphosphate necessary to maintain the cycle. |  | What is the name of the seven carbon intermediates in stage II of the Calvin cycle? | Sedoheptulose-1,7-bisphosphate and sedoheptulose-7-phosphate | Figure 17.22 | What is the oxygenase reaction catalyzed by ribulose-1,5-bisphosphate carboxylase? | Ribulose-1,5-bisphosphate + O2 <=> phosphoglycolate + 3-phosphoglycerate + H+ |  | What is the part of the Calvin cycle where carbon dioxide is trapped as a carboxylate and reduced to the aldehyde-ketone level found in sugars? | Stage I |  | What is the part of the Calvin cycle where the molecule that accpeted carbon dioxide is regenerated called? | Stage II |  | What is theoretical efficiency of photosynthesis? | 0.35 |  | What is unusual about the thylakoid membranes of chloroplasts? | They contain only a small fraction of common phospholipids and a high content of glycolipids. |  | What molecule is used to shuttle CO2 from the mesophyll cells to the bundle sheath cells in C4 plants? | Malate | Figure 17.26 | What stimulates activity of ribulose-1,5-bisphosphate carboxylase? | High pH, CO2 and magnesium |  | What types of plants minimize the wastefulness of photorespiration? | C4 plants | Figure 17.25 | When is the oxygenase activity of ribulose-1,5-bisphosphate carboxylase favored? | Mostly under conditions of high O2 and low CO2. |  | Where are chlorophyll and accessory pigments located in a plant? | Thylakoid membranes |  | Where are protons pumped during photosynthesis in bacteria? | Out of the cytosol and into the periplasmic space |  | Where do C4 plants concentrate their Calvin cycle (C3) photosynthesis? | In specialized bundle sheath cells. | Figure 17.26 | Where does absorption of light and all of the light reactions occur within a chloroplast? | Within or on a thylakoid membrane |  | Where does the oxygen come from that is released in photosynthesis? | Water |  | Where in a chloroplast do all of the synthetic dark reactions occur? | Stroma |  | Where in the plant is CO2 bound to ribulose-1,5-bisphophate? | In the stroma of the chloroplast. |  | Which catabolic enzymes in plants are inhibited by light-dependent mechanisms? | Phosphofructokinase (glycolysis), Glucose-6-phosphate dehydrogenase (Pentose phosphate pathway) |  | Which plant photosystem does the photosynthetic complex of Rhodopseudomonas viridis most resemble? | Photosystem II |  | Why do plants appear green, for the most part? | Chlorophylls a and b absorb light most strongly in the blue and red postions of the spectrum, reflecting green light. Other plant colors arise from differing amounts of accessory pigments. |  | Why should high pH be a useful activator of ribulose-1,5-bisphosphate carboxylase? | Proton pumping into the thylakoid membrane in the light reactions increases the pH of the stroma, where the enzyme is located. |  | What is the sequence of electron carriers an electron traverses after excitement in photosystem II? | 1. Peophytin |  | 2. Plastoquinone QA |  | 3. Plastoquinone QB |  | 4. Plastoquinol (QH) |  | 5. Cytochrome bf |  | 6. Plastocyanin (PC) |  | What is the sequence of electron carriers an electron traverses after excitement in photosystem I? | 1. Chlorophyll receptor A0 |  | 2. Phylloquinone A1 (also known as vitamin K1) |  | 3. Iron sulfur protein Fx |  | 4. Iron sulfur protein FB |  | 5. Iron sulfur protein FA |  | 6. Ferredoxin |  | 7. NADP+ |  | What is the sequence of electron carriers in cyclic electron flow? | 1. Chlorophyll receptor A0 |  | 2. Phylloquinone A1 (also known as vitamin K1) |  | 3. Iron sulfur protein Fx |  | 4. Iron sulfur protein FB |  | 5. Iron sulfur protein FA |  | 6. Ferredoxin |  | 7. Cytochrome bf |  | 8. Plastocyanin |  | 9. P700 reaction center |  | What is the sequence of electron carriers in the photosynthetic bacterium, Rhodopseudomonas viridis ? | 1. Chlorophyll P870 | Figure 17.19 | 2. Pheophytin (BPh) |  | 3. Quinone QA |  | 4. Quinone QB |  | 5. QH |  | 6. Cytochrome bc1 complex |  | 7. Cytochrome c |  | What are the reactions by which sucrose is made in plants? | 1. UTP + glucose-1-phosphate <=> UDP-glucose + Pi |  | 2. UDP-glucose + fructose-6-phosphate <=> UDP + sucrose-6-phosphate |  | 3. Sucrose-6-phosphate + H2O <=> Sucrose + Pi |  | What steps occur in photorespiration? | 1. Phosphoglycolate is dephosphorylated and passed into the peroxisomes | Figure 17.24 | 2. Oxidation of phosphoglycolate yields H2O2 and glyoxylate. |  | 3. H2O2 is broken down by catalase. |  | 4. Glyoxylate is amidated to make glycine |  | 5. Two molecules of glycine are converted in the mitochondria to serine, CO2, and NH3. |  | 6. Serine is converted in a series of steps back to 3-phosphoglycerate. |  | Why is photorespiration inefficient? | 1. Ribulose-1,5-bisphosphate is lost from the Calvin cycle. |  | 2. Oxygen is consumed and CO2 is released. |  | 3. Only a part of the carbon is returned to the chloroplast. |  | 4. ATP is needlessly expended. |  | What are keys to the efficiency of the C4 plants? | The enzyme, phosphoenolpyruvate carboxylase: |  | 1. Lacks the oxygenase of ribulose-1,5-bisphosphate carboxylase. |  | 2. Has a much lower KM for CO2 than ribulose-1,5-bisphosphate carboxylase. |  | 3. If photorespiration does occur, it can be largely salvaged by surrounding mesophyll cells and returned to the Calvin cycle. |

In which direction are protons pumped in photosynthesis? | From the stroma into the thylakoid lumen. |  | In which photosystem are protons pumped from the stroma into the thylakoid lumen? | Photosystem II |

What is different about cyclic electron flow, compared to noncyclic electron flow? | No O2 is released by cyclic electron flow. No NADP+ is reduced by cyclic electron flow. |

Category - Lists

Query - What electron carrier in photosystem II precedes/follows the one shown?

[[Program should pick a an electron carrier and whether a student is to give the preceding or following step. The solution is the appropriate preceding or following step]].

1. Peophytin | 2. Plastoquinone QA | 3. Plastoquinone QB | 4. Plastoquinol (QH) | 5. Cytochrome bf | 6. Plastocyanin (PC)

Category - Lists

Query - What electron carrier in photosystem I precedes/follows the one shown?

[[Program should pick a an electron carrier and whether a student is to give the preceding or following step. The solution is the appropriate preceding or following step]].

1. Chlorophyll receptor A0 | 2. Phylloquinone A1 (also known as vitamin K1) | 3. Iron sulfur protein Fx | 4. Iron sulfur protein FB | 5. Iron sulfur protein FA | 6. Ferredoxin | 7. NADP+

Category - General

Query - What metal atom is contained in the following plant photosystem molecule?

Reversal - there is no reversal

(molecule on left, metal atom in middle, figure on right)

FA | Iron |  | Cytochrome bf | Iron |  | FB | Iron |  | Ferredoxin | Iron |  | Fx | Iron |  | MnC | Manganese |  | Plastocyanin | Copper |

Category - Enzymes

Query - What enzyme catalyzes this reaction?

Reversal

Category - Reactions

Query - What catalytic activity does the enzyme below have?

(Enzyme on left, reaction in center, figures on right)

Fructose-bisphosphate aldolase | Glyceraldehyde-3-phosphate + Dihydroxyacetone phosphate <=> Fructose-1,6-bisphosphate |  | Glyceraldehyde-3-phosphate dehydrogenase | 1,3-Bisphosphoglycerate + NADPH <=> NADP+ + Glyceraldehyde-3-phosphate + Pi |  | Phosphoglycerate Kinase | 3-Phosphoglycerate + ATP <=> ADP + 1,3-bisphosphoglycerate |  | Ribulose-1,5-bisphosphate carboxylase (Rubisco) | Ribulose-1,5-bisphosphate + CO2 + H2O<=> 2 molecules of 3-Phosphoglycerate + 2H+ | Figure 17.20 | Ribulose-5-phosphate Kinase | Conversion of ribulose-5-phosphate to ribulose1,5-bisphosphate (using phosphate from ATP) in stage II of the Calvin cycle. | Figure 17.22 | Triose phosphate isomerase | Glyceraldehyde-3-phosphate <=> Dihydroxyacetone phosphate. |