Photosynthesis Flashcards
What two types/stages of reactions make up photosynthesis?
- Light dependent
- Light independent
Name four photosynthetic pigments
- Chlorophyll a
- Chlorophyll b
- Beta carotene
- Xanthophylls
Why is it beneficial to a plant to have multiple photosynthetic pigments?
- So they can absorb a wider range of wavelengths of light
- As different pigments absorb different wavelengths
What is a photosystem?
- A collection of accessory pigments arranged as a funnel
- With two chlorophyll a molecules at the bottom/centre of the funnel (the reaction centre)
What is photolysis?
- The splitting of water molecules
- Into hydrogen ions and oxygen
- During photosynthesis
What role does NADP have in photosynthesis?
- Acts as a hydrogen acceptor
- And so it is reduced to become reduced NADP
In non-cyclic photophosphorylation, where do the electrons come from to replace those lost in photosystem II?
- The photolysis of water
- (Hydrogen dissociates into protons/hydrogen ions and electrons)
In non-cyclic photophosphorylation, where do the electrons come from to replace those lost in photosystem I?
-From photosystem II
To enable NADP to be reduced, where do:
a) the electrons come from?
b) the hydrogen ions come from?
a) From photosystem I
b) From the photolysis of water
What is cyclic photophosphorylation?
- Only involves photosystem I
- The electrons return back to the same photosystem that they came from originally
What enzyme is used in the light independent stage/the Calvin cycle?
- Rubisco
- Which catalyses the first reaction in the cycle
How is carbon dioxide used in the Calvin cycle?
- Combined with ribulose bisphosphate
- To produce 2x glycerate 3-phosphate
What are the products of the Calvin cycle?
- ADP + Pi (from phosphorylation)
- NADP
- Glucose, amino acids, and lipids (from triose phosphate)
What is the difference between an absorption spectrum and an action spectrum?
- Absorption spectrum shows how much light is absorbed at different wavelengths
- Action spectrum shows the rate of photosynthesis at different wavelengths
What is the law of limiting factors?
-The rate of a physiological process will be limited by the factor which is in shortest supply
