Term
| What is a stomata? What is its purpose? |
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Definition
| A stomata is a pore on the epidermis of plant leaves which allows for gas exchange. |
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Term
| What are the major products and reactants of photosynthesis? |
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Definition
CO2 + H2O + light energy -> C6H12O6* + O2
*glucose may be replaced with other carbohydrates |
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Term
| Does the O2 product of photosynthesis come from the CO2 or H2O reactant? |
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Definition
| It comes from the H2O reactant. |
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Term
| What two processes can photosynthesis be divided into? Where does each process take place? |
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Definition
| Photosynthesis begins with light reactions on the membrane of a thylakoid. It continues with the Calvin cycle, which takes place in the stroma. |
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Term
| What happens during light reactions? |
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Definition
Light from the sun excites electrons on a photosystem I (P700) or photosystem II (P680), which results in a cyclic electron flow (only in I) or a non-cyclic electron flow (happens in both).
In a cyclic electron flow, a pigment (chlorophyll a or b or carotene) has its electrons excited. These electrons move to the reactant site and then the primary acceptor (both are pigments). Once there, the electrons travel down an electron transport chain which provides energy for chemiosmosis, which produces ATP. The electron then returns to PSI.
In a non-cyclic electron flow, a pigment on PSII has its electrons exicted. These travel down an ETC to PSI, giving energy for ATP synthesis. Then, the electrons reach PSI's primary acceptor, and go down another ETC to reduce NADP+ to NADPH.
PSII gets the electron back from water, which gets reduced to molecular oxygen, protons and electrons.
The oxygen leaves through a stomata, and the protons go on to help with ATP synthesis. |
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Term
| What happens during the Calvin cycle? |
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Definition
CO2 is taken from the environment along with NADPH and ATP from the light reactions. NADPH provides electrons and protons and reduces CO2 onto RuBP(a three carbon sugar). This reaction is catalyzed by a RUBISCO protein.
The resulting product is GP3, a basic carbohydrate which can be used in synthesis of more complex ones.
Only one molecule of GP3 is released per reaction, the others go back into making more RuBP. |
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Term
| What color does the chlorophyll of plants absorb and transmit? |
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Definition
| The chlorophyll in plants transmits green and highly absorbs red and blue. |
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Term
| How is light energy absorbed in plants? What is a photosystem? |
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Definition
Light energy is absorbed during light reactions on the thylakoid membrane of chloroplasts.
They absorb light through two photosystems: photosysytem I(AKA P700, @700 nm) and photosystem II (AKA P680, @ 680 nm). When light hits a photosystem's antenna (a pigment molecule - chlorophyll a or b), their electrons move to an excited state and are transferred to the reaction center which transfers the electron to the primary acceptor. They then go down an ETC to give the energy for protons to enter the Thykaloid space. The protons will then rush back into the stroma and fuel ATP synthase. |
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Term
| How is ATP synthesized with photophosphorylation? |
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Definition
| Photophosphorylation is the oxitadtive phosphorylation of plants. Protons from the reduction of water and those found in the stroma are actively transported from the stroma in the chloroplast to inside of a thykaloid. They then rush down their gradient through ATP synthase to energize the production of ATP. |
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Term
| What makes C4 plants and CAM plants different? |
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Definition
C4 plants are found in dry climates. They have adapted to seperate CO2 fixation and the Calvin cycle in different cells.
CAM plants are found in drier climates. They have adapted to serpate CO2 fixation and the Calvin cycle by time.
If the stomata were wide open all day in dry climates, the water needed for photosynthesis would evaporate. |
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