D Flashcards
What are the products of the splitting of water by photolysis in the light-dependent stage of photosynthesis?
Hydrogen ions (protons) and oxygen
Photolysis is the process where water is split by light energy during photosynthesis.
What is synthesized during photophosphorylation in the light-dependent reactions?
ATP
Photophosphorylation refers to the process of adding a phosphate group to ADP to form ATP.
What does reduced NADP combine with in the light-dependent stage of photosynthesis?
Hydrogen ions
Reduced NADP is formed when NADP combines with hydrogen ions.
What are the two types of photophosphorylation?
Cyclic and non-cyclic
The type of photophosphorylation depends on the pattern of electron flow in photosystems.
Which photosystem is involved in cyclic photophosphorylation?
Photosystem I
Cyclic photophosphorylation exclusively involves photosystem I.
What is formed during cyclic photophosphorylation?
ATP
Unlike non-cyclic photophosphorylation, cyclic photophosphorylation does not produce reduced NADP.
In cyclic photophosphorylation, what happens to the electron after it is excited in photosystem I?
It returns to the reaction centre
The electron is excited to a higher energy level but ultimately returns to its original state.
Fill in the blank: ATP and reduced NADP are passed from the light-dependent stage to the _______.
light-independent stage
The light-independent stage is also known as the Calvin cycle.
What is the process called when electrons are emitted from the chlorophyll molecule?
Photoactivation
Photoactivation occurs when chlorophyll absorbs light energy, leading to the excitation of electrons.
What captures the excited electrons in the thylakoid membrane?
An electron acceptor
The electron acceptor initiates the transfer of electrons along the electron transport chain.
What happens to electron carriers as they pass electrons along the chain?
They are alternately reduced and oxidised
Reduction occurs when a carrier gains an electron, while oxidation occurs when it passes the electron to the next carrier.
What happens to the energy of electrons as they move along the electron transport chain?
They gradually lose energy
This energy loss is utilized for various cellular processes, including the active transport of protons.
What is actively moved from the stroma into the thylakoid space?
Protons
The movement of protons creates a concentration gradient essential for ATP synthesis.
What is the term for the movement of protons down their concentration gradient through ATP synthase?
Facilitated diffusion
This process allows protons to flow back into the stroma, driving ATP synthesis.
What is synthesized by adding P to ADP?
ATP
ATP synthesis is a crucial step in cellular energy production.
What is the overall process of using a proton gradient to synthesize ATP called?
Chemiosmosis
Chemiosmosis occurs in both chloroplasts and mitochondria, demonstrating a similarity in energy production mechanisms.
True or False: The process of chemiosmosis in chloroplasts is identical to that in mitochondria.
True
Both processes involve the use of a proton gradient to drive ATP synthesis.
What is non-cyclic photophosphorylation?
Non-cyclic photophosphorylation involves both photosystems in the ‘Z scheme’ of electron flow.
What happens when energy from light is absorbed by photosystems during non-cyclic photophosphorylation?
Excited electrons are emitted from their reaction centres.
What do the emitted electrons from photosystems get absorbed by?
Electron acceptors.
What is the role of the electron emitted from photosystem II?
It is used to form ATP.
What does the electron emitted from photosystem I produce?
Reduced NADP.
How is NADP similar to NAD?
NADP is very similar to NAD that is used in respiration.
How are the electrons lost from the photosystems replaced?
Photosystem I receives the electron from photosystem II, and photosystem II receives an electron from the splitting of water.
What is the function of the water-splitting enzyme in photosystem II?
It catalyses the breakdown of water.
What is another name for the water-splitting enzyme?
Oxygen-evolving complex or water-splitting complex.
What are the products of the photolysis of water?
Hydrogen ions (protons), electrons, and oxygen.
Fill in the blank: The equation for the photolysis of water is H2O → _______ + _______ + _______.
2H* + 2e + ½O.
What is a waste product of the process described?
Oxygen
Oxygen diffuses out of the chloroplast and is eventually lost from the cell or used in mitochondria for aerobic respiration.
What do hydrogen ions combine with in photosystem I?
Electrons and NADP
This combination leads to the formation of reduced NADP.
What is the equation for the formation of reduced NADP?
2H+ + 2e + NADP → reduced NADP
This reaction involves hydrogen ions, electrons, and NADP.
What are the products of the light-dependent reactions?
ATP and reduced NADP
These products are utilized in the light-independent reactions.
Fill in the blank: The ATP and reduced NADP synthesized in the light-dependent reactions can be used in the _______ reactions.
light-independent
