31 terms

AP Biology Photosynthesis Vocabulary

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photosynthesis
the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to make food
autotrophs
organisms that are able to make their own food
chlorophyll
green pigment in plants that absorbs light energy used to carry out photosynthesis
mesophyll
The ground tissue of a leaf, sandwiched between the upper and lower epidermis and specialized for photosynthesis
stomata
Pore-like openings in leaves that allow gases (CO2 and O2) and water to diffuse in and out of the leaves.
stroma
The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water.
light reactions
phase of photosynthesis where energy form light dependent reactions is used to produced glucose and additional ATP molecules
calvin cycle
The second of two major stages in photosynthesis (following the light reactions), involving atmospheric CO2 fixation and reduction of the fixed carbon into carbohydrate.
NADP+
An acceptor that temporarily stores energized electrons produced during the light reactions.
Photophosphorylation
The process of generating ATP from ADP and phosphate by means of a proton-motive force generated by the thylakoid membrane of the chloroplast during the light reactions of photosynthesis.
carbon fixation
The incorporation of carbon from carbon dioxide into an organic compound by an autotrophic organism.
wavelength
the distance from the peak of one light or sound wave to the peak of the next
visible light
electromagnetic waves that are visible to the human eye
absorption spectrum
The range of a pigment's ability to absorb various wavelengths of light.
chlorophyll a
A type of blue-green photosynthetic pigment that participates directly in the light reactions.
action spectrum
A graph that profiles the relative effectiveness of different wavelengths of radiation in driving a particular process.
chlorophyll b
A type of yellow-green accessory photosynthetic pigment that transfers energy to chlorophyll a.
carotenoids
An accessory pigment, either yellow or orange, in the chloroplasts of plants. By absorbing wavelengths of light that chlorophyll cannot, they broaden the spectrum of colors that can drive photosynthesis.
photosystem
light-collecting units of the chloroplast
reaction center
Complex of proteins associated with two special chlorophyll a molecules and a primary electron acceptor. Located centrally in a photosystem, this complex triggers the light reactions of photosynthesis. Excited by light energy, one of the chlorophylls donates an electron to the primary electron acceptor, which passes an electron to an electron transport chain.
primary electron acceptor
A specialized molecule sharing the reaction center with the chlorophyll a molecule; it accepts an electron from the chlorophyll a molecule.
photosystem 1
One of two light-capturing units in a chloroplast's thylakoid membrane; it has two molecules of P700 chlorophyll a at its reaction center.
photosystem 2
One of two light-capturing units in a chloroplast's thylakoid membrane; it has two molecules of P680 chlorophyll a at its reaction center
noncyclic electron flow
A route of electron flow during the light reactions of photosynthesis that involves both photosystems and produces ATP, NADPH, and oxygen. The net electron flow is from water to NADP+.
cyclic electron flow
A route of electron flow during the light reactions of photosynthesis that involves only photosystem I and that produces ATP but not NADPH or oxygen.
rubisco
the enzyme that catalyzes the first step of the Calvin cycle (the addition of CO2 to RuBP, or ribulose bisphosphate).
C3 plants
A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate.
photorespiration
A metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output; generally occurs on hot, dry, bright days.
C4 plants
A plant that changes Co2 into a four carbon compound before entering the Calvin cycle for photosynthesis
PEP carboxylase
An enzyme that adds carbon dioxide to phosphoenolpyruvate (PEP) to form oxaloacetate.
CAM photosynthesis
The photosynthetic pathway in which carbon fixation takes place at night, and the resulting carbon acids are stored until daylight when they are broken down into pyruvate and CO2.
-arid climates
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