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Electrons for photosystem II come from the splitting of water molecules during the light-dependent reactions of photosynthesis. This process, known as photolysis, occurs in the thylakoid membranes of chloroplasts. The electrons released from water molecules replace those lost by chlorophyll molecules in photosystem II, allowing the photosystem to continue the electron transport chain and ultimately produce ATP and NADPH for the Calvin cycle.
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Where do the electron get their energy in photosystem 1?
They pass through a series of compounds to photosystem I, losing energy along the way. Photosystem I, like photosystem II, emits high-energy electrons in the light, and the electrons from photosystem II replace these. Photosystem II contains chlorophyll molecules. When a photon (quantum of light) reaches one of these chlorophyll molecules, the light energy activates an electron. This is then passed to the reaction center of the photosystem, where there are two molecules of chlorophyll P680. These pass the electrons to plastoquinone, which, like the chlorophylls, is embedded in the thylakoid membrane. The plastoquinone changes its position within the membrane, and passes the electrons to cytochromes b6 and f. At this stage the electrons part with a significant proportion of their energy, which is used to pump protons (H+) into the thylakoid lumen. These protons will later be used to generate ATP by chemiosmosis. The electrons now pass to plastocyanin, which is outside the membrane on the lumen side. Photosystem I is affected by light in much the same way as photosystem II. Chlorophyll P700 passes an activated electron to ferredoxin, which is in the stroma (the liquid outside the thylakoid). Ferredoxin in turn passes the electrons on, reducing NADP+ to NADPH + H+. Photosystem I accepts electrons from plastocyanin. So, effectively, photosystem II donates electrons to photosystem I, to replace those lost from photosystem I in sunlight. How does photosystem II recover electrons? When it loses an electron, photosystem II becomes an oxidizing agent, and splits water: 2H2O forms 4H+ + 4e- + O2. The electrons return photosystem II to its original state, and the protons add to the H+ concentration in the thylakoid lumen, for later use in chemiosmosis. The oxygen diffuses away.
Which complex or enzyme of photosynthesis consumes h2o?
The complex known as Photosystem II in the thylakoid membrane of chloroplasts is responsible for splitting water (H2O) into oxygen, protons (H+), and electrons during the light-dependent reactions of photosynthesis. This process provides the electrons needed to generate ATP and NADPH for use in the Calvin cycle.
Electrons from what replaces the electrons from photosystem 2 during noncyclic electron flow?
water
How do the reaction centers of photosystem you and II differ?
Photosystem 1 has chlorophyll a molecule which absorbs maximum light of 700 nm and is called P700 whereas photosystem 2 has chlorophyll a molecule which absorbs light of 680 nm and is called P680.
Where do electrons get their energy in photosystem I?
In photosystem I, electrons get their energy from the absorption of light by chlorophyll molecules. When light is absorbed, it excites the electrons in the chlorophyll, allowing them to move through a series of electron carriers in the photosystem to generate energy for the production of ATP and NADPH during photosynthesis.
Electrons from what replace the electrons form photosystem 2 during non cyclic electron flow?
During non-cyclic electron flow, electrons come from water molecules that are split by photosystem II. These electrons replace the ones lost by photosystem II as they are passed along the electron transport chain.
Where do electrons get their energy in photosystem II?
From energy in photons
How many times are electrons energized during photosynthesis?
The thylakoid membrane contains 2 photosytems, known as Photosystem I and Photosystem II. Together, they function to absorb light and transfer energy to electrons.
What sequence accurately reflects the flow of electrons in photosynthesis?
In photosynthesis, electrons flow from water molecules to photosystem II, then to photosystem I, and finally to NADP+ ultimately producing NADPH. Along the way, the electrons generate a proton gradient that drives ATP production.
How photosystem I and II replenish its lost electrons?
Splitting of water molecules
The chlorophyll known as P680 has its electron holes filled by electrons from what a. photosystem I. b. photosystem II c. water d. NADPH e. accessory pigments?
Oxidized P680 receives its electrons, from water oxidization. (2H2O --> O2 + 4H+ + 4e-).
Water participates directly in the light reactions of photosynthesis by?
Water participates directly in the light reactions of photosynthesis by donating electrons to photosystem II during the process of photolysis. These electrons are used to replace the ones lost by chlorophyll when it absorbs light energy, allowing the photosystem to continue absorbing light and generating ATP and NADPH for the Calvin cycle.
After electrons leave photosystem II they go into an electron transport chain of three protein complexes Where do they go after that electron transport chain?
They go into photosystem I.
Which photosystem most likely envolved first?
Photosystem II most likely evolved first because it provides the energy for producing ATP and passes its electrons to photosystem I.
Where do the excited electrons flowing through photosystem you originally come from?
The excited electrons flowing through photosystem II come from water molecules that are split during the light-dependent reactions of photosynthesis. This process, known as photolysis, releases oxygen as a byproduct and provides electrons to replace those lost when chlorophyll is excited by sunlight.
What happens to electrons when pigments in photosystem II absorbs light?
they move through an electron transport chain to photosystem 1
Where do electrons get there energy from photostem 2?
Electrons in photosystem II get their energy from sunlight. When photons from sunlight are absorbed by the chlorophyll molecules in the photosystem, the energy is transferred to electrons, allowing them to become excited and drive the process of photosynthesis.
