Photosynthesis Flashcards
Where does the light independent reaction take place
In the stroma
Where does light dependant reaction take place
In the grana
What is the significance of the leaf to photosynthesis
Large SA to capture light
Air spaces in the spongy mesophyll to allow co2 to diffuse
Thin so light can penetrate
What is the significance of the chloroplast to photosynthesis
Large Sa for max absorption of light
Rotate within palisade
How are plants cells significant in photosynthesis
Transparent cuticle and epidermis so light penetrates through to the mesophyll
Large vacuole in palisade cells
Chloroplasts form a single layer so they don’t shade each other
How to chloroplasts act as transducers
Turn light energy into chemical energy
What wavelengths does chlorophyll a absorb
435 to 680
Blue or green light
What wavelength does chlorophyll b absorb
480 to 650
Yellow or green
What does b carotene absorb
425 to 480 orange
What does xanthophyll absorb
400 to 500
Yellow
What does an absorption spectrum show
How much light a particular pigment absorbs at different wavelengths
What does an action spectrum show
Rate of photosynthesis at different wavelengths of light
What is the enzyme in the light independent reaction
Rubisco
How can carbohydrates be synthesised from Calvin cycle
Fructose bisphosphate can be converted to glucose and added to fructose to make sucrose for transport around plant
How can fats be synthesised from the Calvin cycle
Acetyl co enzyme A can be made from GP and make fatty acids
TP can be made into glycerol
Fatty acids and glycerol combine to make triglycerides
how do chloroplasts act as transducers
they turn light energy into chemical energy
what is the structure of a photosystem
located in the thylakoid membrane
consists of an antenna complex which contains the pigments and a reaction centre
what is cyclic photophosphoryation
when ATP can be produced by electrons that take a cyclical pathway and are recycled back into chlorophyll A in ps1
what is non cyclic photophosphorylation
ATP produced by electrons that take a linear pathway from water , through ps1 and ps2 to NADP which they reduce
what is a summary of cyclic phosphorylation
ps1 absorbs photons which excites chlorophyll molecules
electrons are emitted and picked up by an electron carrier and then passed down an electron transport chain and transported back to ps1
energy released down ETC phosphorylates ADP to ATP
what is a summary of non cyclic phosporylation
electrons are not returned to ps1 so chlorophyll has a positive charge , which is neutralised by electrons from ps2
electrons from ps2 are excited and pass down electron transport chain to ps1 which makes energy available for phosphorylation to ADP
what is a summary of the light independent reaction
RuBP combines with co2 catalysed by ribulose bisphosphate carboxylase
6c compound splits to two molecules of GP
GP is reduced to TP by reduced NADP with energy from ATP
NADP reforms
how does co2 concentration affect photosynthesis
as it increases the rate of light independent reaction increases
how does light intensity affect the rate of photosynthesis
in darkness light independant reaction is still possible but no oxygen is produced
as light intensity increases light dependant reaction increases so rate increases
at levels that are too high photosynthetic pigments are damaged which decreases rate
what is the light compensation point
the light intensity at which a plant has no net gas exchange as the volume of gases used and the volume of gases produced in respiration and photosynthesis are equal
How is an action spectrum measured
mass of carbohydrate synthesised by plants at different wavelengths of light
what 3 things maintain the proton gradient
the proton gradient
photolysis of water in thylakoid space
removal of protons from the stroma reducing NADP
What is the light compensation point
the light intensity where the plant has no net gas exchange volume of gases used and produced in respiration and photosynthesis are equal
