11 photosynthesis Flashcards
stages of light-dependent reaction
- light energy absorbed by chlorophyll excites electrons, raising their energy levels , this leads to photoionisation of chlorophyll
- electrons transferred to electron carrier become reduced and pass along electron transfer chain, through a series of redox reaction, each at a lower energy levels
- energy released is used to pump H+ through proton pump from the storm to the thylakoid, creating a high conc of H+ in the thylakoid space
- protons along with protons from photolysis pass through ATP synthase which catalyses the formation of ATP
- electrons and protons combine with NADP to form NADPH
3 ways chloroplasts are adapted to carry out the light-independent reaction
- fluid of the stroma contains enzymes needed to carry out the light-independent reaction
- stroma fluid surrounds the grana and so the products of light-dependent reaction can readily diffuse into the storm
- contains DNA and ribosomes so it can efficiently manufacture proteins involved in the light-independent reaction
what is saturation point?
the point when changing a particular factor has no further effect and another limiting factor takes over
where does the light-independent reaction take place?
the stroma of chloroplasts
what is chemiosmosis?
the diffusion of hydrogen ions through a partially permeable membrane, linked to the production of ATP
what are the sources of energy for the Calvin cycle?
ATP and NADPH
equation for photosynthesis
6CO2 + 6H2O -> C6H12O6 +6O2
3 adaptations of leaves for photosynthesis
- large surface area that absorbs as much light as possible
- arrangement of leaves that minimises overlapping, avoiding shadowing
- transparent cuticle and epidermis let light through to the photosynthetic mesophyll cells beneath
where does light-dependent reaction take place?
thylakoid membrane
products of light-dependent reaction
ATP and NADPH
products of photolysis
electrons, protons and oxygen
what happens during photolysis?
- photon of light splits water into protons, electrons and oxygen
- electrons produced replace electrons in chlorophyll molecule
what is oxidation and reduction?
oxidation - loss of electrons or loss of hydrogen or gain of oxygen
reduction - gain of electrons of gain of hydrogen or loss of oxygen
order of compounds formed during the Calvin cycle
RUPB - GP - TP
what are the compounds of the Calvin cycle composed of?
RuBP - a 5-carbon sugar
GP - a 3-carbon acid (x2)
TP - a 3-carbon sugar (x2)
what is carbon fixation?
the process by which carbon dioxide is converted to organic compounds
what is photoionisation?
light energy absorbed by chlorophyll molecule, its electrons gain energy and move to higher energy levels, ionising the chlorophyll molecule
what is photophosphorylation?
conversion of ADP to ATP using light energy
3 ways chloroplasts are adapted for the light-dependent reaction of photosynthesis
- thylakoid membrane provides large surface area for attachment of chlorophyll, electron carriers and enzymes
- thylakoid membrane has ATP synthase channels which catalyse production of ATP
- chloroplasts contain DNA and ribosomes so they can manufacture proteins involved in the light-dependent reaction
what enzyme catalyses reaction between CO2 and RuBP?
rubisco
how is GP converted to TP
NADPH is used to reduce GP to TP using energy supplied by ATP
what is TP converted to?
- organic molecules such as glucose, starch, lipids etc
- used to regenerate RuBP using ATP
what are photosystems?
where pigments are stored/produced
what is chemiosmosis?
diffusion of protons (H ions)
why is it an advantage that plants contain a mixture of pigments?
a wider range of wavelengths of light is absorbed
so more light energy is absorbed for photosynthesis because more photoionisation of chlorophyll
