photosynthesis Flashcards
adaptions of the leaves for photosynthesis
lots of stomata short diffusion pathway to mesophyll cells
thin shorter diffusion pathway
transparent cuticle
air spaces in lower mesophyll space constant supply of air
large SA
xylem for input of water
what do chloroplasts consist of
thylakoids- disc like structures where 1st stage of photosyn takes place large SA for chlorophyll
inner and outer membrane - large SA permeable
grana - stacks of thylakoids
intergranal lamella- tubular structures between grana
stroma - fluid filled matrix second stage occurs here. contains enzymes for photosyn
describe the light dependent stage
in thylakoids
light hits chlorophyll exciting electrons
electrons leave chlorophyll and pass along electron protein carriers in thylakoid membrane this is photoionisation of chlorophyll.
some of the energy released by electrons is used to make ATP.
catalysed by ATP synthase embedded in membranes
what else does light do in the light dependent stage
photolysis
water provides protons for the reduction of NADP and electrons to replace those lost from the chlorophyll
releases O2 as waste product
what does the light dependent stage make
NADPH ATP O2
describe the light independent stage (calvin cycle)
happens in the stroma
CO2 enters stroma and combines with RuBP (5 carbon) using the enzyme rubisco
makes 2 x GP (3 carbon)
GP is reduced to make 2 x TP (3 carbon) ATP and NADPH from stage one used here - ATP provides energy for rxn and NADPH provides the H
some TP used to make glucose others used to regenerate RuBP which uses ATP
what does the light dependent stage make
glucose (regenerates RuBP) and needs ATP
what is radioactive co2 used for
track the stages of light independent rxn. it becomes incorporated into new compounds
what is the effect of higher temp on photosyn
increases rate of photosyn/respiration as its an enzyme controlled reaction. more kinetic energy more collisions more enzyme substrate complexes formed
what is a photosynthometer used for
measure the rate of photosynthesis. usually measures O2 released or CO2 taken up
what are the limiting factors of photosyn
light, temp, and CO2 conc.
co2 normally main one
how to see if its a limiting factor on a graph
if it goes diagonally up limiting factor is the IV
if flattens out it something else
what are the similarities between photosyn and resp
use and release ATP use chain of electron carriers processes controlled by enzymes use redox reactions involve cycles of reactions
