Table of Contents
- 1 What happens when light energy excited electrons in photosystem II?
- 2 When light energy excites electrons in photosystem II Where do the electrons to replace them come from?
- 3 Where do electrons get their energy in photosystem I?
- 4 What happens when photosystem II absorbs light?
- 5 What happens to photons as they travel through the photosystem?
- 6 Where does energy absorbed by sunlight go in photosynthesis?
What happens when light energy excited electrons in photosystem II?
What happens when light energy excites electrons in photosystem II? Electrons are released into the electron transport system.
When light energy excites electrons in photosystem II Where do the electrons to replace them come from?
Photosynthetic eukaryotes and cyanobacteria have two photosystems – Photosystem II and Photosystem I. Light energy causes the excitation and loss of an electron from a PSII reaction center chlorophyll (P680). Water is oxidized to replace the lost electron, generating H+ ions and oxygen (O-2) ions.
Where do replacement electrons come from in photosystem II?
Photosystem II obtains replacement electrons from water molecules, resulting in their split into hydrogen ions (H+) and oxygen atoms. The oxygen atoms combine to form molecular oxygen (O2), which is released into the atmosphere.
How are the excited electrons replaced in photosystem II?
First vertical bar: Photosystem II electrons are energised by light (electrons replaced by photolysis of water molecules) Diagonal bar: Electrons lose energy as they pass through an electron transport chain (synthesising ATP)
Where do electrons get their energy in photosystem I?
When light photons excite the pigments in the light-harvesting complexes of the photosystem, their electrons get excited. These electrons come from the process the directly proceeds Photosystem I, which is the electron transport chain.
What happens when photosystem II absorbs light?
When light is absorbed by one of the pigments in photosystem II, energy is passed inward from pigment to pigment until it reaches the reaction center. There, energy is transferred to P680, boosting an electron to a high energy level (forming P680*).
What happens to the electrons that are lost by Photosystem I?
What happens to the electrons that are lost by photosystem 1? The electrons go to reduce the NADP to NADPH. Oxidation is the process of losing an electron. Since electrons are the main source for energy, the reaction also loses energy.
Where does the electron go after it is used in photosynthesis?
After the energy is used, the electron is accepted by a pigment molecule in the next photosystem, which is called photosystem I (Figure 2). Figure 2. From photosystem II, the excited electron travels along a series of proteins.
What happens to photons as they travel through the photosystem?
A pigment molecule in the photosystem absorbs one photon, a quantity or “packet” of light energy, at a time. A photon of light energy travels until it reaches a molecule of chlorophyll. The photon causes an electron in the chlorophyll to become “excited.”
Where does energy absorbed by sunlight go in photosynthesis?
This electron transport system uses the energy from the electron to pump hydrogen ions into the interior of the thylakoid. A pigment molecule in photosystem I accepts the electron. In the light-dependent reactions, energy absorbed by sunlight is stored by two types of energy-carrier molecules: ATP and NADPH.
What happens in the light dependent reaction of photosynthesis?
The proton gradient powers ATP synthase, a protein that phosphorylates ADP to form ATP. In the light-dependent reaction of photosynthesis, light energy generates ATP. Light energy excites electrons and raises the energy level of electrons in chlorophyll.