3.5.1 Photosynthesis Flashcards
Of PS1 and PS2, which is at a higher energy level?
PS1
Which photo system undergoes cyclic photo-phosphorylation?
Photo system 1
What is the process of the electron transport chain in cyclic photo-phosphorylation?
Light enters PS1
Some electrons are excited
These are elevated to a higher energy level
This is oxidation as electrons are lost from the chlorophyll
Electronic acceptor gains electrons (reduction)
Electrons move to an acceptor at a higher level to a lower one
This releases energy
Electrons then move onto a third receptor, releasing more energy
Electron moves back into PS1
How is ATP formed during cyclic photo-phosphorylation?
Energy is created by electrons in redox reactions
The energy released is used to phosphorylate ADP to form ATP
What is the product of cyclic photo-phosphorylation?
ATP
What is the process of non-cyclic photo-phosphorylation?
Occurs at the same time as cyclic Occurs in PS2 PS1 is oxidised Electrons pass down the electron transport chain The energy is used to make ADP Final acceptor is NADP Produces reduced NADP
Why is the process in PS2 non-cyclic?
The chlorophyll did not replace the electrons as it is non-cyclic
Where does PS2 recieve it’s electrons from?
From water
Light can split water in a process called photolysis
Forms oxygen and two hydrogen ions
Hydrogen ions lose electrons which then move into the chlorophyll
What are the products of non-cyclic photo-phosphorylation?
ATP and NADP
Where is the light absorbed in the leaf?
Most is absorbed by the palisade layer
Some is absorbed by the spongy mesophyll
Some moves all the way through
The waxy cuticle and upper epidermis reflects green light
What is photosynthesis?
A process used to convert light energy into chemical energy that can be used to fuel the organism’s activities
What is chlorophyll?
A group of 5 pigments
Why do plants appear green?
The chlorophyll pigments absorb very little green light
Where does photosynthesis occur?
In the photosystem of the thylakoid membrane
Where does light need to reach for photosynthesis?
The reaction centre of the photosystem
