3.5.1 Photosynthesis Flashcards
Describe the structure of a chloroplast
Double membrane bound thylakoid stacks (grana). Linked by thylakoid membrane (lamellae). ATP synthase and chlorophyll pigments present in thylakoid membrane/stroma
Why do plants have accessory pigments?
To absorb a wider range of wavelengths of light
what evidence is there that chloroplasts used to be free-living cyanobacteria?
Own circular DNA free from histones, 70S ribosomes, double membrane surrounding them
What is found within the stroma?
Grana/oil droplets/starch/enzymes/sugars/ ribosomes/DNA
Where does the light dependent stage of photosynthesis take place?
Thylakoid membrane
Where does the light independent stage of photosynthesis take place?
Stroma
What structural features of the thylakoids increase rate of photosynthesis?
Stacked into granum/increased surface area/maximum absorption of light in membrane
What is a photosynthetic pigment?
Coloured substances that absorb the light energy needed for photosynthesis (e.g. chlorophyll)
What is a thylakoid?
A system of interconnected, flattened fluid filled sacs with proteins embedded in the membranes, where the light dependent stage takes place
Describe the stroma
Gel-like fluid surrounding the thylakoids. contain all the enzymes, sugars and organic acids needed for the light independent reaction.
Where the Calvin cycle occurs ?
Stroma
What are the products of the Calvin cycle?
NADP, ADP and glucose
What happens to light energy when it enters the chloroplast ?
Absorbed by the photosynthetic pigments and used to excite electrons so that they can leave chlorophyll (photoionisation). They are then replaced by the splitting of water (photolysis) into H+ ions, electrons and oxygen.
How do the electrons move along the electron transport chain in photosynthesis?
A series of redox reactions
State the name for the synthesis of ATP using light ?
Photophosphorylation
What is produced from the photolysis of water?
Two hydrogen ions, one oxygen, two electrons
What happens to the electrons when they leave the electron transport chain (photosynthesis) ?
Combine with one hydrogen ion and NADP to form NADPH
How many times does the Calvin cycle have to happen to form one glucose molecule ?
Six
How does GP turn into TP?
It is reduced. The H atom comes from NADPH and ATP provides energy for the endothermic reaction