Photosynthesis Flashcards
Adaptions of leaf
Large sa for light absorption
Thin to allow light to penetrate and small DP
Minimised overlapping of leaves
Transparent epidermis to allow light to penetrate
Many stomata so SDP to cells
Air spaces so large SA and faster diffusion (gas phase)
What are the 3 main stages of Photosynthesis
Capturing light
Light dependent reaction LDR
Light independent reaction LIR
Where does the the light dependent reaction occur
Across thylakoid membrane
Stages of LDR
Photo lysis
Photo ionisation
Describe photolysis
The splitting of 2 water molecules using light into 4 electrons 4 H+ and an oxygen molecule
What is the purpose of photolysis
H+ contribute to conc gradient
Electrons replace electrons lost from chlorophyll
Oxygen used in Respiration or waste
Describe photo ionisation
A chlorophyll molecule absorbs light energy
Electrons become excited and are raised an energy level
Describe the LDR
Photo ionisation causes electrons from chlorophyll to be moved down ETC releasing energy
Energy used to pump H+ from stroma into thylakoid lumen using proton pump, creating concentration gradient
H+ Diffuse down gradient into stroma via ATP synthase.
Energy released used to produce ATP (photophosphorylation)
Electrons and protons reduce NADP to form reduced NADP
How is chloroplast adapted for LDR
Thylakoid membrane= increase SA for attachment of electrons, chlorophyll and enzymes
Network of proteins hold chlorophyll in specific manner to get max light absorption
Grabal membranes are permeable to allow H+ to diffuse across
DNA and ribosomes in stroma to synthasis any enzymes needed
How are the LDR and LIR linked
Products of LDR = used in LIR reaction
ATP
Reduced NADP
What occurs in the LIR
Calvin cycle
Describe the LIR
Ribulose bisphosphate (RuBP) combines with co2 and rubisco (enzyme) to form 2x glycerate phosphate
ATP and reduced NADP react with gp to form 2x triose phosphate
Triose phosphate regenerated using ADP and Pi to form RuBP and release one carbon
How many calvin cycles are necessary to produce one glusoce molecule
6
How. Many carbons in
RuBP
Gp
Triose phosphate
5
3
3
How is the chloroplast adapted for the LIR
Stroma surround thylakoid so SDP for products of LDR
stroma is contained so concentrated source of enzymes
Ribosomes and DNA = quick manufacture of enzymes
