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make carbon-based molecules from suns energy
make carbon based molecules by oxidizing inorganic chemicals (
Photoautotrophs are _______
primary producers in ecosystems because they are the first point which sugars are produced. All ecosystems rely upon primary producers for a source of fixed carbon
An organelle found in plant and algae cells where photosynthesis occurs ( found in the mesophyll cells)
_____ enters chloroplast through photosynthesis and ____ exists
cholophyll is in the membrane of ______
thylakoids (stacks called granum)
energy + 6CO2 + 6H2O -> C6H12O6 + 6O2
what becomes oxidized and reduced in photosynthesis?
6co2----> c6h12o6 becomes reduced
6h20----> 6o2 becomes oxidized
Is photosynthesis endergonic or exergonic?
endergonic; the energy boost is provided by light
electrons relationship in photosynthesis:
are resource/commodity, not a product and are provided by water
two stages of photosynthesis
light reactions ("photo") and the calvin cycle ("synthesis")
light reactions consist of the following biochem reactions; (3)
1. spilt h20 to generate electrons; this releases o2 as
2. use light to excite electrons derived from water
3. Electrons move through the electron transport chain and
i) reduce NADP+ to NADPH
ii)Generate ATP from ADP by photosynthesis
light-independent reactions of photosynthesis in which energy from ATP and NADPH is used to covalenty add CO2 to an organic molecule, which can then be used to make glucose
a wave that transfers electric and magnetic energy through empty space. ( light is ex)
The distance between two corresponding parts of a wave ( wavelength determines the type of electromagnetic energy)
visible light consists of a ______ wavelength
narrow range wavelength
Our brain interprets these wavelengths as _______ because three similar kinds of recpetors called _______that absorb light at different wave lengths
reason the world sees in rich textures and hues as our brain interpolate the signals derived from these receptors
plants receive wavelengths through
A quantum, or discrete quantity, of light energy that behaves as if it were a particle.
plants absorb light in which two colours of the spectrum?
red and blue
when you look at an object ..... you see the colours that.......
were NOT absorbed by an object.
Why do leaves appear green?
chlorophyll reflects and transmits green light
a graph plotting a pigment's light absorption versus wavelength
which two colours work best for photosynthesis?
voliet-blue and red
A profile of the relative performance of the different wavelengths in photosynthesis. ( theoder w engelman)
-in the experiment, he exposed different segments of a filamentous algae to different wavelengths
-areas receiving wavelengths favourable to photosynthesis produced more 02
-measued 02 production
Main photosynthetic pigment
accessory pigment photosynthesis
of cholophyll b , carotenoids
absorb excessive light that would damage chlorophyll
Why do fall leaves change color?
Fall color change occurs when the plants stop producing chlorophyll and the remaining pigments become visible because they are not blocked by the abundance of green pigment.
what happens when chlorophyll is "excited by light?" (fluroscience)
-depends on location
-when the isolated molecule of chlorophyll absorbs light, one of the electrons on it goes from a ground state to excited state (unstable)
-eixcted electrons fall back to the ground state, energy in the form of photons are given off (fluroscience)
a reaction-center complex surrounded by light-harvesting complexes ( type of protein complex)
light havesting complexes
(pigment molecules bound to proteins) transfer the energy of photons to the reaction center
what happens when a photon first reacts with a photosystem?
usually interacts with antenna pigment molecules, which transfer the energy to chlorophyll a
what happens next?
primary electron acceptor in the reaction center accept excited electron and its reduced as a result
Step #1: Overview of energy transfer through both photosystems:
1) A photon hits a pigment and its energy is passed among pigment molecules until it excites P680. On the way, it loses no energy, due to resonant energy transfer.
Step #2: Overview of energy transfer through both photosystems:
2) An excited electron from P680 is transferred to the primary electron acceptor (we now call it P680+)
Step #3: Overview of energy transfer through both photosystems:
H2O is split by enzymes in the membrane, and an electron is transferred from the hydrogen atoms to P680+, thus reducing it to P680 (O2 is released as a by-product of this reaction)
Step #4: Overview of energy transfer through both photosystems:
4) Each electron "falls" down an electron transport chain (should be familiar now) from the primary electron acceptor of PS II to PS I
Energy released by the fall drives the creation of a proton gradientacross the thylakoid membrane (this part should be familiar to you)
Step #5: Overview of energy transfer through both photosystems:
5) Diffusion of H+ (protons) across the membrane drives ATP synthesis (should also be familiar)
Step #6: Overview of energy transfer through both photosystems:
6) In PS I (like PS II), transferred light energy excites P700, which loses an electron to an electron acceptor
-P700+ (i.e. P700 minus an electron) accepts an electron passed down from PS II via the electron transport chain
Step #7: Overview of energy transfer through both photosystems:
7) Each electron "falls" (through re-dox reactions) down an electron transport chain from the primary electron acceptor of PS I to the protein ferredoxin (Fd)
Step #8: Overview of energy transfer through both photosystems:
8) The electrons are then transferred to NADP+ which reduces it to NADPH
-•The electrons of NADPH are available for the reactions of the Calvin cycle
•This process also removes an H+ from the stroma
in summary, light reactions:
generate ATP and increase the potential energy of electrons by moving them from H2O to NADPH
Calvin cycle uses ____ and ____ to reduce fixed ___ to ________
ATP and NADH
-co2 to sugar
why does Calvin cycle regenerate its starting material?
The cycle builds G3P by using ATP and reducing power of electrons carried by NADPH, along with protons
carbon dioxide enters the Calvin cycle as co2 and leaves as sugar named
Calvin cycle has 3 phases
-reduction of intermediates
why does the cycle go around 3 times?
carbons prefixed one at a time, but the sugar that is produced is a 3-carbon sugar
How plants conserve water
close their stomata to conserve H20 (elicited gas exchanges in leaves, which means co2 goes down and o2 goes up
Reaction in which rubisco attaches oxygen instead of carbon dioxide to ribulose bisphosphate ( can reduce as much as 50 percent of the carbon fixed that could have been by the Calvin cycle )
Photorespiration consumes ____ and organic fuel and releases _____ but it costs _______
separate the initial fixation of CO2 from its entry into the Calvin cycle
-special arrangement of bundle-sheath cells and mesophyll cells that permits this separation
fix co2 into malate at NIGHT when its cooler and store it in the vacuoles
C4 and CAM difference
c4 plants relocate the CO2 molecules to minimize photorespiration while CAM plants choose when to exact CO2 from the environment
C4 and CAM similarity
both fix C02 first into an organic acid prior to incoporation of those co2 molecules into the Calvin cycle
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