CH-11: Photosynthesis in Higer Plants - SET 2 Flashcards
What steps are involved in the photochemical phase of photosynthesis?
- Light absorption
- Water splitting
- Release of oxygen
What is the photochemical phase of photosynthesis responsible for?
The photochemical phase or the light reactions are thought to be responsible for the formation of high-energy chemical intermediates, ATP and NADPH
What are photosynthetic units or pigment systems?
Group of pigment molecules which take part in the conversion of light energy into chemical energy
Name the two photosynthetic units.
- Photosystem I (PS-I)
- Photosystem II (PS-II)
What is a reaction centre?
Possessed by each photosynthetic unit, the reaction center is made of a specific chlorophyll a molecule which absorbs light energy of long wavelength. It ca release electron upon absorption of energy.
What is the absorption peak of the reaction center in PS-I?
700nm
(hence the reaction center is known as P700)
What is the absorption maximum of the reaction center in PS-II?
680nm
(hence the reaction center is known as P680)
What is the reaction center surrounded by?
It is surrounded by a number of light harvesting pigment (LHP) molecules (also called antenna molecules)
What is the function of the antenna molecules?
They absorb photons of different wavelengths and transfer this energy to the reaction center
What are the complexes of the harvesting molecules occur known as?
Light harvesting complexes
LHC-I and LHC-II
What are the pigment molecules of the light harvesting complexes bound to? What is its function?
Proteins. They help to make photosynthesis more efficient.
What is the reaction center of Photosystem I/ Pigment system I known as?
P700
What is the reaction center of Photosystem II/ Pigment system II known as?
P680
Where does the PS I lie?
On the outer surface of the thylakoids
Where does the PS II lie?
On the inner surface of thylakoids
Where is the PS I found?
Found in grana and stroma lamellae
Where is the PS II found?
Found in grana only
In which type of flow of electrons does the PS I participate in?
It participates in both cyclic and non-cyclic flow of electrons
In which type of flow of electrons does the PS II participate in?
It is involved only in non-cyclic flow of electrons
Which photosystem is associated with splitting of water and release of oxygen?
PS II
What term did Arnon use to refer to ATP and NADPH?
Assimilatory powers
Define photophosphorylation.
The process of formation of ATP and ADP and inorganic phosphate (iP) utilizing light energy is called photophosphorylation
What is the electron transport chain?
A series of electron carriers over which electrons pass in a downhill journey releasing energy at every step that is used in generating an electrochemical proton (H+) gradient which helps in synthesizing ATP
In which series do the two photosystems work during non-cyclic photophosphorylation?
First PS II and then PS I
