photosynthesis Flashcards
Autotrophs
Organisms that generate their own organic matter through photosynthesis
why are plant leaves green
because they reflect or transmit t green light, or they do not absorb wavelengths of green light
adaptations of leaves for photosynthesis and explain how these help in photosynthesis
large surface area: helps to capture the maximum amount of light
thin: light is able to penetrate right through the leaf. also, it creates a short diffusion pathway for the diffusion of CO2
permeable: they have stomata, which allow carbon dioxide to diffuse into the leave
have air spaces:this allows carbon dioxide to diffuse into all the cells of the leaf
cuticle and epidermis are transparent, so light is able to pass through them easily to the chloroplasts.
adaptations of palisade mesophyll cells for photosynthesis
large vacuole
they are cylindrical, elongated, and at right angles to the surface of the leaf. Due to this, light has to pass through the epidermal cells and only one palisade mesophyll cell before reaching the chloroplast.
contain a large number of chloroplasts, so the maximum amount of light can be trapped
the function of the chloroplasts
to absorb light energy and convert it into chemical energy
where are photosynthetic pigments found in the chloroplast
in the thylakoid membranes
stacks of thylakoid membranes
grana/ granum
where are chlorophylls found, what are they and what is their function
in the thylakoid membrane
green pigment that captures light for photosynthesis
functions of starch and lipid droplets in chloroplasts
they store the products of photosynthesis
function of the stroma
contains enzymes for photosynthesis
the function of the outer membrane of the chloroplast
contains the contents of the stroma, like photosynthetic enzymes in the chloroplast, preventing them from mixing with the contents of the cytoplasm
I am the site of the light-independent reactions
stroma
I am the site of the light-dependent reactions
thylakoid membranes
why are starch grains used as carbohydrate stores in the chloroplast
because starch does not affect the water potential as it is insoluble
Why does the chloroplast have a double membrane
to control the movement of substances in and out of the chloroplast
advantage of the leaves having more than one photosynthetic pigment
enables the leaves to absorb various wavelengths of light. So more light is absorbed overall if there are more pigments
main photosynthetic pigments involved in harvesting light energy
chlorophyll a
chlorophyll b
carotenoids
difference between chlorophyll a and chlorophyll b
chlorophyll a has a methyl group attached to it while chlorophyll b has a carbonyl group attached
chromatography
a separation technique first used to separate pigments in plant leaves
Rf value
the value that shows how far a component has traveled compared to the solvent front
formula for Rf
distance moved by component/ distance moved by solvent front
Plants take up minerals from the soil. These are combined with the products of the light-independent
stage to produce other molecules needed by the plant.
Give three examples of minerals taken up from the soil and state what molecules are produced when
each example combines with the products of the light-independent stage.
nitrates, to serve as a source of nitrogen for protein synthesis and the synthesis of nucleic acids
phosphate for the synthesis of phospholipids
magnesium for chlorophyll synthesis
State why only some of the triose phosphate produced by the Calvin cycle can be used to produce
hexose phosphate.
Some TP is needed to regenerate more RUBP
Diuron is a weed killer which is a very specific and sensitive inhibitor of photosynthesis. It blocks the
electron carrier binding site on photosystem II. This stops the electron flow from where it is generated, in
photosystem II, to the electron carrier. This reduces the ability of the plant to convert light energy into
chemical energy.
Diuron only blocks electron flow from photosystem II. It has no effect on photosystem I or other reactions
in photosynthesis, such as light absorption or carbon fixation in the Calvin cycle.
(a) Explain the effects of Diuron on non-cyclic photophosphorylation and why cyclic photophosphorylation
is not affected.
it stops electrons from being transferred from PSII to PSI
so NADP is not reduced to NADPH
Cyclic photophosphorylation only involves PS1
so it is not stopped as electrons are passed from PS1 and returned to PS1
Use your knowledge of photosynthesis to explain the role of photosynthetic pigments in the
production of ATP.
Pigments in PSII absorb light energy
electrons excited emitted from the reaction center
used to power proton pumps to generate an electrochemical gradient
movement of protons through ATP synthase allows for ATP production
in photosystem 1, what is the reaction centre called and why?
p700 because it contains a chlorophyll molecule with a maximum absorption at wavelength 700nm
in photosystem 2, what is the reaction centre called and why
p680 because it contains a chlorophyll molecule with maximum absorption at wavelength 680nm
