Practice free Botany NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
What is the key role of NAD+ in the conversion of pyruvate to Acetyl CoA?
In the reaction, NAD+ is converted to NADH + H+, indicating that NAD+ acts as an electron and hydrogen ion acceptor, undergoing reduction. This is an oxidative step for pyruvate.
Which of the following events directly contributes to the establishment of a proton gradient across the thylakoid membrane during the light reaction, according to the chemiosmotic hypothesis?
The context states: 'Splitting of water molecules is associated with PS II resulting in the release of O2, protons and transfer of electrons to PS II.' This release of protons inside the thylakoid lumen directly contributes to the proton gradient.
According to the chemiosmotic hypothesis, where does the accumulation of protons primarily occur in order to drive ATP synthesis?
The text mentions: 'During this process a proton gradient is created across the membrane of the thylakoid.' and 'The breakdown of the protons gradient due to movement through the F0 part of the ATPase enzyme releases enough energy for synthesis of ATP.' This implies protons accumulate inside the thylakoid lumen.
The movement of protons from the thylakoid lumen to the stroma occurs through which part of the ATP synthase enzyme?
The context explicitly 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 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.
Ready to ace NEET?
Free access · No credit card required
Yes. You can attempt every Botany question on this page for free without logging in, and check the correct answer with a detailed explanation instantly.
No account is required to attempt questions and view answers. A free account adds bookmarks, personal notes, and progress tracking.
The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.