OCR 5.6 Photosynthesis Flashcards
What is the granum?
inner part of the chloroplast made of stacks of thylokoid membranes, where the light dependent stage takes place
What is a photosystem?
a group of photosynthetic pigments in the thylakoids that trap photons
What is the stroma?
fluid filled matrix of chloroplasts, where the light dependent stage takes place
What is a thylakoid?
flattened membrane-bound sac found inside the chloroplasts; contains photosyntheitc pigments and photosytems and is the site of the light dependent reaction.
Where does the light dependent stage take place?
stroma
What wavelength of light does PS2 absorb?
680nm
What wavelength of light does PS1 absorb?
700nm
What wavelengths of light do carotenoids absorb?
400-500nm
What wavelengths of light do Xanthophylls absorb?
375-550nm
What wavelengths of light do chlorophyll b absorb?
400-500nm & 640nm
What wavelengths of light do chlorophyll a absorb?
680/700nm & 440nm
Why do most plants appear green?
Because they do not absorb green light (no photsynthtic pigments in that range
How do you calcluate Rf values?
distance traveled by pigment / distance travelled by solvent
What happens to water in the light dependent stage of photosynthesis?
It is split (by light) to produce H+ ions, 1/2 O2 molecule and electrons
Where do the electrons from water go in the light dependent stage?
replace the electrons lost from PS2
Where do the electrons from PS2 go in the light dependent stage?
Down an electron transport chain (to produce ATP) and then replace the electrons lost from PS1.
Where do the electrons from PS1 go in the light dependent stage?
To NADP reductase to produce NADPH
What is cyclic photophosphorylation?
Electrons are excited and produce ATP in PS1 only. It does not go onto reduce NADP
What is photophosphorylation?
The phosphorylation of ADP to produce ATP using light
What is carbon fixation?
Changing CO2 to an organic molecule during photosynthesis.
What does RuBP join with in the Calvin cycle? What does it form?
CO2 (with RuBisCo)
It forms two Glycerate-3-phosphate molecules
What happens to 2x GP in the Calvin cycle?
It reduced using NADPH & ATP to form triose phosphate
What happens to 2 x TP in the Calvin cycle?
One molecule is used to create proteins, glucose and lipids.
One molecule remains in the cycle and converts to RuBP
What is the name for GP?
Glycerate 3 phosphate
What is the name for TP?
Triose phosphate
What are the limiting factors of photosynthesis?
Carbon dioxide, light intensity and temperature.
How does temperature affect the calvin cycle?
denatures the enzymes and stops the cycle
Why does reduced CO2 stop the Calvin cycle?
CO2 is not added to RuBP and GP molecules cannot be formed
What are the products of the light dependent cycle needed for the Calvin cycle?
NADPH & ATP
