Photosynthesis Flashcards
What is an autotroph?
An organism which makes complex organic compounds from simple inorganic compounds
What is a heterotroph?
An organism that obtains complex organic compounds by feeding on other organisms or their dead remains
What are the parts of a chloroplast?
-Chloroplast Envelope = double membrane
-Ribosomes
-Circular DNA
-Granum = stack of thylakoid membranes
-Thylakoid Membranes = form the grana, is the site of light-dependant reactions
-Starch Grain = insoluble carbohydrate storage product of photosynthesis
-Stroma = matrix of chloroplasts, site of light-independent reactions
-Lipid Droplet = energy store made from the sugars produced during photosynthesis
What is a photon?
Light travels in packages called photons which contain a mixture of different wavelengths of light
Why does not all of the sunlight that lands on a plant get turned into sugar by photosynthesis?
-Some of the light misses the chloroplasts
-Some of the light is reflected from the surface of leaves
-Some of the light goes right through the leaf
-Some of the radiations are transmitted as heat
-Some of the light is the wrong wavelength
What are pigments in the chlorophyll?
Chlorophyll is a mixture of closely related pigments
-Chlorophyll A = blue/green
-Chlorophyll B = yellow/green
-Cartenoids = orange carotene and yellow xanthophyll
-Phaeophytin = grey
What is the absorption spectrum?
The wavelength of light that pigments absorb
What is the action spectrum?
The wavelengths of light that affect the rate of photosynthesis
What is photophosphorolyation?
Conversion of ADP to ATP using the energy of sunlight
-Allows a phosphate to be added
What is photolysis?
When the energy of light allows the split of molecules e.g. water
Where does the light dependant reaction happen?
Thylakoid membranes
What happens in the light dependant reaction in PS1?
- Sunlight (photons) hit chlorophyll in PS1 making electrons excited
- Electrons leave the molecule
- Electrons move down the electron transport chain and each movement releases energy to synthesise ATP
- Electrons return to the thylakoid membrane and the cycle repeats
What happens in the light dependant reaction in PS2?
- Sunlight (photons) hit chlorophyll molecule making electrons excited
- Electrons leave the molecule
- Electrons move down the electron transport chain, each movement releases energy to synthesise ATP
- Electron moves to PS1
- PS2 is now unstable
- Water molecules in the cell spontaneously dissociate (split) and the released electron replaces the lost one
- NADP takes hydrogen ions to become reduced NADP and the hydroxide ions form oxygen
What stage is cyclic photophosphoroylation?
Light dependant stage in PS1
What stage is non-cyclic in photophosphorolyation?
Light dependant stage in PS2