3.5.1 photosynthesis Flashcards
how is the palisade cell having lots of chloroplasts an adaptation?
large concentration of chlorophyll, absorbs as much light for photosynthesis as
how is the palisade cells having chloroplasts that are able to move with the cytoplasm an adaptation?
absorb light from any direction
how is the palisade cells being long and narrow an adaptation?
many cells can be packed into the surface layers of the leaf
how is the palisade cells having many leucoplasts an adaptation?
to store starch , the insoluble polymer produced in photosynthesis will not alter the water potential
how is palisade cells having many mitochondria and RER an adaptation?
to provide energy for synthesis of proteins such as enzymes and carrier proteins
how do palisade cells having a large permanent vacuole be an adaptation?
to store cell sap which is a sugary solution that maintains cell turgor supports the cells holding the plant upright to absorb as much light as possible
what are the features of the chloroplast?
inner membrane
inter membrane space
outer membrane
ribosomes
stroma
starch grain
lipid droplet
granum
inter granar membrane
thylakoids
why does the chloroplast have its own circular DNA and ribosomes?
in order to able to synthesise its own proteins
what are the three meanings of oxidation?
loss of electrons
loss of hydrogen
gain of oxygen
what are the three meanings of reduction?
gain of electrons
gain of hydrogen
loss of oxygen
what are the 2 stages of photosynthesis?
light dependent reaction
Calvin cycle (light dependent reaction)
where do light dependent reactions take place?
thylakoid membranes
outline what happens in a light dependent reaction
light energy is absorbed by chlorophyll
electrons in chlorophyll become excited and are released from the chlorophyll (photoionisation)
what is the energy from the light dependent reaction used for?
to make ATP from ADP and Pi (phosphorylation)
make reduced NADP
splitting of water into protons, electrons and oxygen (photolysis)
what is a coenzyme?
a molecule that aids the function of an enzyme
what is the coenzyme used in photosynthesis?
NADP
what are the 2 types of phosphorylation?
non cyclic
cyclic
what is non-cyclic phosphorylation?
- produces ATP, NADPH and oxygen
- uses both photo systems
- electrons are passed to NADP
what is cyclic phosphorylation?
-produces ATP only
- only uses photo system 1
- electrons are not passed onto NADP instead are passed back to photo system 1
- only produces small amount of ATP
explain what happens during the photoionisation of chlorophyll
light energy is absorbed by chlorophyll in photosystem 2
light energy excites electrons in chlorophyll
electrons move to higher energy level and released from chlorophyll
explain what happens in photolysis of water
excited electrons that have left the chlorophyll have to be replaced
light energy splits water into protons, electrons and oxygen
explain what happens during photophosphorylation
electrons moving down electron transport chain lose energy that is used to transport more protons into the thylakoid
thylakoid has higher proton concentration than stroma
proton gradient across membrane
protons move down gradient via ATP synthase complex back into stroma
explain what happens during reduction of NADP
light energy is absorbed by photosystem 1
this excites electrons to an even higher energy level
these electrons are transferred to NADP in the stroma along with protons to form NADPH
what is chemiosomotic theory?
movement of electrons down electron transfer chain
coupled to the transfer of protons into the thylakoid to build an electrochemical gradient
movement of protons back across a membrane down electrochemical through ATP synthase complex
outline what happens in the Calvin cycle
CO2 is fixed to RUBP catalysed by the enzyme Rubisco
thus produces 1 highly unstable 6C molecule which immediately breaks down to 2 molecules of GP
GP is reduced to TP (gains hydrogen)
using the hydrogen transferred from reduced NADP
using energy transferred from hydrolysis of ATP
1/6 of TP is converted to useful organic substances
5/6 is used to regenerate RUBP so the cycle can continue
what is a compensation point?
rate of photosynthesis = rate of respiration
