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What is the primary consequence of the 'breakdown of the proton gradient' across the thylakoid membrane?
The text clearly states: 'The breakdown of the protons gradient due to movement through the F0 part of the ATPase enzyme releases enough energy for synthesis of ATP.'
Which of the following statements correctly describes the role of electron transport in the chemiosmotic hypothesis?
While not explicitly detailed in the provided text how electron transport causes proton pumping, the overall understanding of chemiosmosis is that electron flow through PS II and PS I drives proton movement (via carriers) from the stroma into the thylakoid lumen, thus establishing the gradient. The text mentions 'After absorbing light, electrons are excited and transferred through PS II and PS I and finally to NAD forming NADH. During this process a proton gradient is created across the membrane of the thylakoid.' This strongly implies that electron transport is intrinsically linked to the creation of the proton gradient.
Which component is NOT directly involved in establishing the proton gradient for chemiosmosis in photosynthesis?
The F0 part of ATPase is responsible for the breakdown of the proton gradient to synthesize ATP, not its establishment. Photolysis of water releases protons into the lumen, and electron carriers between PS II and PS I transfer electrons and pump protons from the stroma to the lumen.
If the thylakoid membrane were to become highly permeable to protons, what would be the immediate consequence for ATP synthesis?
The chemiosmotic hypothesis relies on the maintenance of a proton gradient. If the membrane became permeable, the gradient would dissipate, removing the driving force for ATP synthesis.
The energy currency generated during the light reaction as a result of the chemiosmotic hypothesis is:
The text states: 'The breakdown of the protons gradient due to movement through the F0 part of the ATPase enzyme releases enough energy for synthesis of ATP.'
What is the source of the protons ($H^+$) that accumulate in the thylakoid lumen during the light reaction, contributing to the proton gradient?
The context explicitly mentions: 'Splitting of water molecules is associated with PS II resulting in the release of O2, protons and transfer of electrons to PS II.' These protons are released into the thylakoid lumen.
Which of the following is an INCORRECT statement regarding the chemiosmotic hypothesis in photosynthesis?
The F0 part of ATPase is responsible for the proton channel (transmembrane channel) that allows protons to move back, while the F1 part catalyzes the actual synthesis of ATP from ADP and Pi using the energy released. The text specifically refers to the F0 part's role in movement of protons leading to ATP synthesis.
Which of the following statements best describes the chemiosmotic hypothesis in the context of photosynthesis?
The chemiosmotic hypothesis, as explained, focuses on how the proton gradient across the thylakoid membrane, built during the light reaction, is utilized by ATP synthase to produce ATP. The context states 'During this process a proton gradient is created across the membrane of the thylakoid. The breakdown of the protons gradient due to movement through the F0 part of the ATPase enzyme releases enough energy for synthesis of ATP.'
What is the fate of the electrons transferred after light absorption by PS II and PS I, and their ultimate role in energy transduction before ATP synthesis?
The text states: 'After absorbing light, electrons are excited and transferred through PS II and PS I and finally to NAD forming NADH. During this process a proton gradient is created across the membrane of the thylakoid.' The formation of NADH (presumably NADPH in context of photosynthesis) is coupled with the creation of the proton gradient.
Which enzyme plays a dual role, acting as both a carboxylase and an oxygenase, leading to photorespiration in C3 plants?
The NCERT text states: 'RuBisCO also catalyses a wasteful oxygenation reaction in C3 plants: photorespiration.' This clearly identifies RuBisCO as the enzyme responsible for initiating photorespiration due to its oxygenase activity.
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