Light Reactions of Photosynthesis quiz #3 Flashcards
Light Reactions of Photosynthesis quiz #3
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What are the main products of the light reactions of photosynthesis?
The main products are ATP, NADPH, and oxygen gas (O2). Which photosystem is involved first in the light reactions, and what does it do?
Photosystem II is involved first; it absorbs light energy and uses it to energize electrons from water. What is the role of the electron transport chain in the light reactions?
The electron transport chain transfers energized electrons from photosystem II to photosystem I, pumping protons to create a gradient. What is the final electron acceptor in the light reactions?
NADP+ is the final electron acceptor, becoming reduced to NADPH. What is chemiosmosis, and how does it relate to ATP synthesis in the light reactions?
Chemiosmosis is the movement of protons down their concentration gradient through ATP synthase, driving the production of ATP. What is the fate of the oxygen produced during the light reactions?
Oxygen is released as a byproduct and can diffuse out of the plant into the atmosphere. What is the role of light energy in the light reactions?
Light energy excites electrons in the photosystems, enabling their transfer through the electron transport chain. What is the stroma, and what is its role in the light reactions?
The stroma is the fluid-filled space outside the thylakoids; it receives ATP and NADPH for use in the Calvin cycle. What is the function of ATP synthase in the light reactions?
ATP synthase uses the energy from the proton gradient to convert ADP and inorganic phosphate into ATP. What is the main purpose of the light reactions in photosynthesis?
The main purpose is to convert light energy into chemical energy in the form of ATP and NADPH. How are electrons transferred from photosystem II to photosystem I?
Electrons are transferred via the electron transport chain embedded in the thylakoid membrane. What is the relationship between the light reactions and the Calvin cycle?
The light reactions supply ATP and NADPH to the Calvin cycle, which uses them to fix carbon dioxide. Why is water essential for the light reactions?
Water provides the electrons needed for the electron transport chain and releases oxygen as a byproduct. How does the light reactions' electron flow contribute to ATP production?
Electron flow powers proton pumps, creating a gradient that drives ATP synthesis via chemiosmosis. How is the energy from sunlight ultimately stored during the light reactions?
The energy is stored in the chemical bonds of ATP and NADPH. What is the function of the electron transport chain in the thylakoid membrane?
It transfers electrons between photosystems and pumps protons to generate a gradient for ATP synthesis. What is the role of protons (H+) in the light reactions?
Protons accumulate in the thylakoid space, creating a gradient used to produce ATP. Why are the light reactions called 'light-dependent' reactions?
They require light energy to excite electrons and drive the production of ATP and NADPH. How does the light reactions' process ensure a continuous supply of electrons?
By splitting water molecules, the process continuously provides new electrons to photosystem II. How does the structure of the thylakoid facilitate the light reactions?
The thylakoid membrane contains the necessary proteins and complexes for the light reactions to occur efficiently. What is the overall equation for the light reactions of photosynthesis?
2 H2O + 2 NADP+ + 3 ADP + 3 Pi + light energy → O2 + 2 NADPH + 3 ATP What is the importance of the light reactions for life on Earth?
They produce oxygen and chemical energy, supporting aerobic life and the biosphere's energy needs. What is the function of the reaction center in a photosystem?
The reaction center contains special chlorophyll molecules that transfer excited electrons to the electron transport chain. What is the significance of the story involving 'Luke and Ryan' in memorizing the light reactions?
The story uses mnemonic devices to help remember the sequence: Photosystem II, Electron Transport Chain, Photosystem I, NADP+ reduction, and Chemiosmosis.
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