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Where does all of our oxygen come from?
Photosynthesis
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How are macromolecules made using sunlight
energy?
- Light excites/energizes chlorophyll. That energy
- is used to make ATP and NADPH which are then used to incorporate CO2 into
- 3-carbon sugar
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Does photosynthesis involve energy transfer or
energy transformation?
- Transformation. Light energy is transformed to
- chemical energy
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Although photosynthesis is often described as an endergonic process, why is it actually an exergonic reaction?
- Heat is being dissipated because very little
- light energy is actually absorbed in the process.
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What is the electron donor in photosynthesis and what is it oxidized to?
H2O is oxidized to O2
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What is the electron acceptor in photosynthesis
and what is it reduced to?
CO2 is reduced to macromolecules such as simple sugars
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What is the difference between NADH and NADPH?
Which is used in photosynthesis?
NADPH includes an extra phosphate group. NADPH
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What does endosymbiosis tell us about the use of chlorophyll and photosynthesis in eukaryotes?
- Other organisms take in chlorophyll containing
- organisms in order to utilize photosynthesis for themselves
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Where do light reactions take place and what is
created (primary and byproduct)?
- In the thylakoids; ATP and NADPH are generates
- as the primary products and O2 is released as a byproduct
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Where does synthesis and the Calvin cycle take
place? What is produced?
In the stroma; G3P is generated from CO2
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There are three different membranes of the
chloroplast. Where are they located?
- Two membranes around the chloroplast, each
- thylakoid within the chloroplast had a phospholipid bilayer
-
Where is light harvested and ATP made in the
chloroplast?
On the thylakoids membranes
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True or false: thylakoids are interconnected in
land plants?
True
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What happens to the excited electrons on the
thylakoid membrane?
They are passed down another electron transport chain and generate NADPH
-
What is the role of chemiosmosis in
photosynthesis?
It drives ATP synthesis
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Where does the calvin cycle take place? What
does it create and from what?
In the Stroma; It uses ATP and NADPH from light reactions to put CO2 into a 3-carbon sugar
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What kind of light energy is used for photosynthesis?
Photons from the sun
-
Does a shorter or longer wavelength result in
photons with more energy?
Shorter
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What color of light is reflected by plants? What
happens to the other colors?
Green; they are absorbed and used for photosynthesis
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Which color of light is used most in
photosynthesis?
Purple, blue, and red
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What are two types of pigments and what do they do?
- Chlorophyll reflects and scatters green light,
- carotenoids reflect and scatter yellow and orange and also transfer light
- energy to chlorophyll and are antioxidants
-
What is chlorophyll chemically composed from?
What is it similar to?
Porphyrin ring and a hydrocarbon tail, “heme” in hemoglobin and cytochromes
-
What does a photosystem do? What are the two parts of the photosystem and their function?
- The photosystem harvests light and is located on the membrane of the thylakoid. Energy from excited photons is first absorbed
- into the pigments of the light-harvesting complex. In the reaction center,
- these electrons pass on their energy to chlorophyll electrons.
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How many photosystems are part of each
thylakoid? What connects them?
- Two connected by an electron transport chain.
- Photosystem II and then Photosystem I.
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Where does Photosystem II get its electrons
from? How does it export them?
H2O; feeds them into electron transport chain
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Where does photosystem II get its electrons
from? What happens to them then?
- Electron transport chain from photosystem I.
- They get re-excited from sunlight energy.
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How many water molecules are required to obtain 4 electrons? What is left over from the removal process and what do they
byproducts do?
- 2; H+ ions and O2 are left over. The H+ ions
- create a high H+ ion concentration within the thylakoid which then drives ATP
- synthesis. The O2 diffuses out of the membrane (passive diffusion because it is
- non-polar and can pass through membrane without any help)
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What is the final electron acceptor after
Photosystem I? What does this form and what process does this go to?
NADP+ accepts the electron to become NADPH; it then moves on to the Calvin cycle.
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What happens to the H+ ions within the thylakoid space? Where do they go?
- They are actively diffused and used to create
- ATP. The ATP molecule then heads to the Calvin cycle
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Where does the Calvin cycle take place? What are the three molecules that go into the Calvin Cycle? What comes out?
In the stroma; CO2, NADPH, and ATP go in; CH2O, NADP+, ADP, and a phosphate group come out
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Describe the path of a CO2 molecule as it enters the Calvin cycle.
- The CO2 is added to ribulose biphosphate
- (5-carbons, similar to ribose) to make a 6-carbon molecule using the enzyme
- Rubisco. This 6-carbon molecule then splits into two 3-carbon molecules. ATP
- and NADPH are then used to make G3P.
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How many G3P molecules need to be created to have a net gain of one G3P molecule?
Six
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What enzyme is responsible for incorporating CO2 into organic molecules?
Rubisco
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What is the most abundant protein on Earth?
Rubisco
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What is all of a plant’s organic molecules made?
How are the extra molecules stored?
In the Calvin Cycle; as starch
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How are the Calvin cycle and Glycolysis similar?
They both make use of G3P
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