Light Reactions of Photosynthesis quiz #2 Flashcards
Light Reactions of Photosynthesis quiz #2
You can tap to flip the card.
Control buttons has been changed to "navigation" mode.
1/35Skip to main content
Where do the light-dependent reactions of photosynthesis take place?
The light-dependent reactions occur in the thylakoids of chloroplasts. Which of the following statements correctly describes a reaction associated with Photosystem II? A) It absorbs photons and energizes electrons from water. B) It reduces NADP+ to NADPH. C) It synthesizes glucose. D) It occurs in the stroma.
A) It absorbs photons and energizes electrons from water. What is the role of the thylakoid membrane in the light reactions of photosynthesis?
The thylakoid membrane hosts the photosystems and electron transport chain, facilitating the light-dependent reactions. What is the primary function of Photosystem II in the light reactions?
Photosystem II absorbs light and uses the energy to split water molecules, releasing oxygen and energizing electrons. What is the final electron acceptor in the light reactions of photosynthesis?
NADP+ serves as the final electron acceptor, forming NADPH. How is ATP generated during the light reactions of photosynthesis?
ATP is generated through chemiosmosis, driven by a hydrogen ion gradient across the thylakoid membrane. What are the main products of the light-dependent reactions?
The main products are ATP, NADPH, and oxygen. What is the significance of the hydrogen ion gradient in the thylakoid space?
The hydrogen ion gradient powers ATP synthesis via ATP synthase. What role does water play in the light reactions of photosynthesis?
Water provides electrons for the electron transport chain and releases oxygen as a byproduct. What is the relationship between the light reactions and the Calvin cycle?
The ATP and NADPH produced in the light reactions fuel the Calvin cycle. Where do the light reactions of photosynthesis take place within the chloroplast?
The light reactions occur in the thylakoid membranes of the chloroplast. What is the initial source of electrons for the light reactions?
Water (H2O) is the initial source of electrons, which are extracted when water is split. What happens to water molecules during the light reactions?
Water molecules are split, providing electrons, protons (H+), and releasing oxygen gas as a byproduct. How is ATP produced during the light reactions?
ATP is produced by ATP synthase through chemiosmosis, using the proton gradient generated across the thylakoid membrane. What is the function of NADPH in photosynthesis?
NADPH carries high-energy electrons to the Calvin cycle for use in carbon fixation. What are the reactants required for the light reactions?
The reactants are light energy (photons) and water (H2O). How are photosystem I and photosystem II different in their sequence of action?
Photosystem II acts first, followed by photosystem I, even though photosystem I was discovered first. What is the significance of the hydrogen ion (proton) gradient in the thylakoid space?
The proton gradient stores potential energy used by ATP synthase to generate ATP. How does the splitting of water contribute to the light reactions?
Splitting water provides electrons for the electron transport chain and releases protons and oxygen. Why are the light reactions necessary for the Calvin cycle?
The light reactions provide ATP and NADPH, which supply the energy and reducing power needed for the Calvin cycle. What happens to NADP+ during the light reactions?
NADP+ is reduced by gaining electrons and a proton to form NADPH. What is the role of pigments in the photosystems?
Pigments absorb light energy and transfer it to electrons, initiating the light reactions. What is the function of the thylakoid membrane in the light reactions?
The thylakoid membrane houses the photosystems, electron transport chain, and ATP synthase, facilitating the light reactions. What is the sequence of major events in the light reactions?
The sequence is: light absorption by photosystem II, electron transport chain, light absorption by photosystem I, reduction of NADP+ to NADPH, and ATP synthesis by chemiosmosis. What is the role of accessory pigments in the light reactions?
Accessory pigments broaden the range of light absorbed and transfer energy to the reaction center. What is the importance of the reduction of NADP+ in the light reactions?
Reduction of NADP+ to NADPH stores high-energy electrons for use in the Calvin cycle. How does the light reactions contribute to the oxygen content of Earth's atmosphere?
The splitting of water during the light reactions releases oxygen gas, which can enter the atmosphere. What happens to the ATP and NADPH produced in the light reactions?
They are used in the Calvin cycle to drive the synthesis of carbohydrates. What is the significance of the order in which photosystem II and photosystem I operate?
Photosystem II acts first to provide electrons and energy, followed by photosystem I, which further energizes the electrons. What is the main difference between the roles of ATP and NADPH in photosynthesis?
ATP provides energy, while NADPH provides reducing power (electrons) for the Calvin cycle. What is the role of the Calvin cycle in relation to the light reactions?
The Calvin cycle uses ATP and NADPH from the light reactions to fix carbon dioxide into sugars. How does the light reactions' process demonstrate energy transformation?
It transforms light energy into chemical energy stored in ATP and NADPH. How does the splitting of water in the light reactions affect the pH of the thylakoid space?
It increases proton concentration, lowering the pH inside the thylakoid space. How does the light reactions' process relate to the concept of redox reactions?
Electrons are transferred through a series of redox reactions, with molecules being oxidized and reduced. Why is the production of ATP and NADPH in the light reactions considered essential for the plant's metabolism?
They provide the energy and reducing power required for synthesizing organic molecules in the Calvin cycle.
04:06
