Photosynthesis Flashcards
Where is the site of photosynthesis?
Leaf
What is the basic word equation for photosynthesis?
Carbon dioxide + water + light -> glucose + oxygen
What are the 3 main stages of photosynthesis?
Capturing of light energy, light dependent reaction and light independent reaction/Calvin cycle
Which plan organelle and pigments is responsible for absorbing the light energy?
Chloroplasts, chlorophyll A and B
What type of phosphorylation is involved in photosynthesis?
Photophosphorylation
What is meant by photophosphorylation?
The addition of a phosphate molecule using light energy
What is the main difference between oxidation and reduction?
Oxidation involves the loss of electron/hydrogen or gain of oxygen whereas reductions involves the gain of electrons/hydrogen or loss of oxygen
Do oxidation and reduction take place together?
Yes
What is meant by photolysis?
The splitting of a molecule using light energy
How is ATP made in the light dependent reaction?
Photophosphorylation
What two types of photophosphorylation occur in the LDR?
Cyclic and non-cyclic
What are the products of non-cyclic photophosphorylation?
ATP, reduced NADP (NADPH) and oxygen
What product is produced in cyclic photophosphorylation?
ATP only
Which photosystem is involved in non-cyclic photophosphorylation?
PS II
Which photosystem is involved in cyclic photophosphorylation?
PS 1
What happens during non-cyclic photophosphorylation?
PS II and electron carriers form an ETC:
- Light energy excites electrons in chlorophyll, which is absorbed by PS II
- Photolysis of water produces protons, electrons and oxygen
- Energy from the excited electrons makes ATP, as the excited electrons move along the chain they lose energy which is used to transport protons into the thylakoid, creating a proton gradient across the membrane
- Protons move down their concentration gradient into the stroma via ATP synthase
- NADPH is generated from the light energy absorbed by PS I, which excites the electrons to a much higher energy level
- Finally the electrons are transferred to NADP with a proton from the stroma to form NADPH
What happens during cyclic photophosphorylation?
Electrons from chlorophyll aren’t passed onto NADP and passed back to PS I via electron carriers. Electrons are recycled and repeatedly flow through PS 1. This is basically the last stages of the LDR continuing to occur, expect no oxygen or reduced NADP is made.
Where does the light dependent reaction take place?
Thylakoid membranes
Where does the light independent reaction take place?
Stroma of chloroplasts
What is the starting compound of the Calvin cycle?
Ribulose bisphospahte (RuBP)
What happens when the first molecule of carbon dioxide combines with RuBP?
An unstable 6-carbon compound is made which quickly breaks down into two molecules of 3-carbon compound GP
What catalyses the reaction between carbon dioxide and RuBP?
Rubisco
How is GP changed into TP during the Calvin cycle?
ATP from the light dependent reactions provides the energy for this to happen, as well as hydrogen ions provided by the NADPH. NADPH is recycled to NADP
What is TP converted to?
Useful organic compounds e.g. glucose
