As electrons move through the electron transport chain of photosystem II, they lose en-ergy. What happens to this energy?ABсDIt is used to establish and maintain a proton gradient.It is used to produce NADPH, which accepts electrons from photosystem I.It excites the electrons in photosystem I.The energy is transferred to unusable heat energy and is lost by the system.

In photosystem II, the reaction centre chlorophyll a absorbs 680 nm wavelength of red light, that…

As electrons move through the electron transport chain of photosystem II, they lose en- ergy. What happens to this energy? A It is used to establish and maintain a proton gradient. B U с D It is used to produce NADPH, which accepts electrons from photosystem I. It excites the electrons in photosystem I. The energy is transferred to unusable heat energy and is lost by the system.

As electrons move through the electron transport chain of photosystem II, they lose en- ergy. What happens to this energy? A It is used to establish and maintain a proton gradient. B U с D It is used to produce NADPH, which accepts electrons from photosystem I. It excites the electrons in photosystem I. The energy is transferred to unusable heat energy and is lost by the system.

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter21: Photosynthesis

Section: Chapter Questions

Problem 18P: The Overall Free Energy Change for Photosynthetic NADP+ Reduction What is the overall free energy...

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The Overall Free Energy Change for Photosynthetic NADP+ Reduction What is the overall free energy change (G) for noncyclic photosynthetic electron transport? 4 (700-nm photons) + 4 (680-nm photons) + 2 H2O + 2 NADP+O2 + 2 NADPH + 2H+
Which of the following substances does not participate in the Calvin-Benson cycle? a. ATP c. NADPH e. PGAL b. O2 d. RuBP f. CO2
Melvin Calvin and Andrew Benson determined the steps in the light-independent reactions of photosynthesis by exposing the green alga Chlorella to CO2 labeled with the radioisotope carbon 14. By looking at which compounds the C14 ended up in, they were able to identify all intermediates in this cyclic pathway. Why did they predict correctly that the same set of intermediates would be formed in the light reaction in land plants?
Match each term with its most suitable description. ____ PGAL formation a. absorbs light ____CO2 fixation b. converts light to chemical energy ____ autotroph c. self-feeder ____ ATP forms NADPH does not d. electrons cycle back to photosystem ____ photorespiration e. problem in C3 plants ____ photosynthesis f. Calvin-Benson cycle product ____ pigment g. water molecules split ____ photolysis in photosynthesis h. rubisco function
Photosynthesis directly opposes respiration in determining how plants influence atmospheric CO2 concentrations. When a leaf is in the light, both photosynthesis and respiration are occurring simultaneously. The data in the Table were collected from the leaf of a sagebrush plant that was enclosed in a chamber that measures the rate of CO2 exchange. The same leaf was used to collect the data in Interpret the Data in Chapter 7. Respiration is shown as a negative and photosynthesis as a positive rate of CO2 exchange. The net photosynthesis rate is the amount of CO2 (in micromoles per square meter per second) assimilated by the leaf while respiration is occurring; a positive value indicates more photosynthesis is occurring than respiration. The light exposed to the leaf is quantified as the number of photons in the 400 to 700 nm wavelength, the photosynthetic photon flux density (PPFD); 2,000 mol/m2/s is equivalent to the amount of light occurring at midday in full Sun. Observation Photosynthetic Photon Flux Density (PPFD) (mol/m2/s) Net Photosynthesis (mol/m2/s) 1 2,000 9.1 2 1,500 8.4 3 1,250 8.2 4 1,000 7.4 5 750 6.3 6 500 4.8 7 250 2.2 8 0 -2.0 Why is net photosynthesis negative when PPFD is zero? Looking at the respiration data from Interpret the Data in Chapter 7, at what temperature do you think these data were collected? Source: Data based on unpublished research by Brent Ewers, University of Wyoming.
Which of the following statements about the light reactions of photosynthesis are correct? 1. Absorption of light does one thing: it makes chlorophyll easier to oxidize. 2. In PSII, the rate of damage to the D1 protein can never exceeds the rate of repair. 3. Electron transport is spontaneous (exergonic) as electrons move from P680* to P700+. 4. Compared to anoxygenic photosynthesis, in oxygenic photosynthesis less light needs to be absorbed to reduce NADP+. A. 1,2 and 3 B. 1 and 3 C. 2 and 4 D. 4 only E. All of 1,2,3 and 4 are correct
After electrons are raised to high energy levels in photosystem II, they travel down an electron transport chain. As they are stepped down in energy, the lost energy is used to power which process. The pumping of high energy electrons into the intermembrane space. This creates a large difference in concentration and in electric charge between the intermembrane space and the lumen of the thylakoid. When these high energy electrons rush back into the thylakoid lumen, they are forced to travel through one of the ATP synthase molecules that sits embedded in the thylakoid membrane. ATP synthase uses the flow of hydrogen ions to phosphorylate ADP, converting it to ATP. The pumping of hydrogen ions into the stroma. This creates a large difference in concentration and in electric charge between the stroma and the lumen (watery interior) of the thylakoid. When When the hydrogen ions in the stroma rush back into the thylakoid lumen, they are forced to…
Choose the CORRECT order of reactions that are conducted by photosystem I. P700 is activated by two photons → two Chl A0 accept two high-energy electrons → one quinone A1 is fully reduced → two electrons are passed on one 4Fe–4S cluster → two molecules of ferredoxin are reduced → ferredoxin–NADP+ reductase takes two protons from the stroma and reduces one NADP+ P680 is activated by two photons → two Chl A0 accept two high-energy electrons → two molecules of ferredoxin are reduced → ferredoxin–NADP+ reductase oxidizes one ferredoxin at a time to reduce FAD to FADH- and then to FADH2 → the proton-motive force is created P700 is activated by a photon → Chl A0 accepts two high-energy electrons → one plastoquinone QA is fully reduced → two electrons are passed on one 4Fe–4S cluster → two molecules of ferredoxin are reduced → ferredoxin–NADP+ reductase takes two protons from the stroma and reduces one FAD P700 is activated by a photon → pheophytin accepts two high-energy electrons →…
Place the following steps of the Light-Reactions of Photosynthesis in order. Production of NADPH Absorption of light Electron transport chain & Production of ATP Photosystem II Photosystem I
Which of the following correctly sequences the steps of non-cyclic electron transport? * Water is oxidized by the capture of light energy; these excited electrons are passed through the dark reactions, returning to chlorophyll during the final light reactions The ATP and NADPH generated by the reactions of photosystem Il and photosystem I are utilized by the Calvin Cycle to build high energy glucose molecules Electrons donated from water molecules pass through photosystem I then O photosystem II before returning to the chlorophyll molecules, generating ATP in the process Chlorophyll molecules absorb UV radiation exciting electrons which flow through photosystem I, returning to the chlorophyll molecules ) This is a required question
Diagram 4: The Light Reactions of Photosynthesis STROMA (low H* concentration) Cytochrome complex Photosystem I Photosystem I Light NADP reductase 4H NADP + H NADPH THYLAKOID SPACE (high H* concentration) 4 H* Thylakoid membrane ATP synthase STROMA (low H concentration) ADP Diagram 4 shows a single thylakoid membrane taken from a chloroplast inside of a the light dependent cycle that take place along the thylakoid membrane In the Thylakoid space water is split into O 02 H* and electrons O H*, ATP and O2 O Photosystem II, electrons and oxygen O 02 and chlorophyll
Where do photosynthetic organisms get the energy needed to make sugars during the light- independent/dark reactions? They use the ATP and NADPH that are produced during the light-dependent reactions. They convert the 6-carbon sugars into 5-carbon sugars. They obtain the energy directly from the Sun. They use the ADP and carbon dioxide produced during the light-dependent reactions.