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Photosynthesis

Terms in this set (41)

What does photosynthesis convert?
Visible light into chemical energy
What chemical word equation summarizes the overall reactions of photosynthesis?
Carbon dioxide + Water -> Oxygen + Sugar
What does the light reactions of photosynthesis include?
Splitting a water molecule into protons, electrons, and oxygen
What does light energy cause in the chloroplast?
Electrons to flow from water to NADP+
Why do leaves of a plant appear green?
The leaves absorb other wavelengths and reflect green
What molecule is synthesized as electrons pass between two photosystems?
ATP
What is light energy absorbed by in the light reaction of photosynthesis?
Chlorophyll and given off as high-energy electrons
How do the the light reactions and Calvin Cycle occur?
They occur simotaniously
In what condition will the Calvin reactions of photosynthesis not proceed?
Without the products of the light reactions
Why doesn't the Calvin cycle operate in the dark?
-Some enzymes of the cycle are inactive in the dark
-The cycle depends on ATP and NADPH from the light reactions
-The stomates close and CO2 becomes unavailable
What is the main light absorbing pigment?
Chlorophyll A
Why does water split during light reactions?
Light energy into hydrogen ions (H+ or protons), electrons, and oxygen gas
How is NADPH formed?
Electrons and H+ ions go to NADP+
When is ATP produced?
When H+ ions diffuse across the thylakoid membrane due to movement of electrons between the 2 photosystems
What does the Calvin Cycle produce?
Sugar molecules (glucose)
How many turns does it take to produce one glucose molecule?
6 turns
What products from light reactions does the Calvin Cycle use?
ATP and NADPH
How is the Calvin Cycle started?
By Carbon fixation
What is Carbon Fixation?
When carbon dioxide combines with RUBP to start the cycle
What are 2 types of autotrophs
Photoautotrophs
Chemoautotrophs
Photoautotrophs
plants, algae, some bacteria

use of sunlight- photosythesis
Chemoautotrophs
Some bacteria

use of chemical reactions (chemicals)- Chemosynthesis
What is the process of photosynthesis?
ABSORPTION- of light energy
CONVERSION- of light energy into chemical energy
STORAGE- of chemical energy
How does light energy travel?
as waves (photon)
What does Chlorophyll A do to visible light in the process of photosynthesis?
It is absorbed/reflected
What is the relationship between wave length and energy?
The shorter the wavelength the more energy
What color light do plants mainly absorb?
Red and Blue
What is the equation of photosynthesis?
6CO2 + 6H2O -> C6H12O6 + 6O2
Where does the Calvin cycle take place?
Stroma
What is photosynthesis?
A 2 part process made up of the light reactions (in the thylakoid) and light independent reactions
Light independent reaction
Calvin Cycle
How is the rates of photosynthesis determined?
By light intensity, temperature, CO2, and O2
What happens after photosynthesis reaches an optimum level?
It either levels off or declines (photoinhibition)
When does photorespiration occur?
When not enough CO2 available and O2 combines with the enzyme RUBISCO, which makes it half as efficient as regular photosynthesis
In conversion when electrons are transported what occurs?
Energy from them pump hydrogen ions inside the thylakoid
What is RUBisCO?
The name of the enzyme involved in carbon fixation.
How is photosynthesis essential to life?
Photosynthesis is the only significant chemical reaction that supplies energy and new organic carbon for life on earth. It also releases large amounts of oxygen into the atmosphere
Why are photosynthetic organisms called producers in an ecosystem?
Photosynthetic organisms are called producers because they produce organic molecules as food for consumers.
How is light used in photosynthesis?
It is used to split water thus releasing electrons, protons (H+) and oxygen. Light supplies the energy that is used to produce ATP and NADPH
What are the products of light reactions and how are they used?
The products are ATP and NADPH, and oxygen. ATP and NADPH supply energy for carbon fixation in the Calvin cycle . Oxygen is released into the atmosphere.
Why does the Calvin cycle not operate at night?
It requires ATP and NADPH which are produced only in the light reactions. Also several of the Calvin cycle enzymes are activated by light. Finally, little carbon dioxide is available when the stomates are closed at night.
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