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Biology Chapter 10 > Light Reactions > Flashcards

Light Reactions Flashcards

1
Q

List the inputs and outputs of light reactions.

A

Inputs: h20 and energy (light)
Outputs: O2, NADPH (NADH w/ phosphate), ATP

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2
Q

Where in the cell do light reactions occur?

A

on the thylakoid membrane

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3
Q

List the inputs and outputs of the Calvin Cycle.

A

Inputs: 3CO2, 6 NADPH, 9 ATP
Outputs: G3P (direct output of photosynthesis)

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4
Q

Where in the cell does the Calvin Cycle occur?

A

stroma

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5
Q

What is the photosynthesis rxn?

A

6 co2 + 6 h20 + energy (light) —-> c6h1206 + 6 o2

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6
Q

Describe autotrophs.

A

“self-feeders” - photosynthesize to make their own food from ions and simple molecules

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7
Q

Describe heterotrophs.

A

“different feeders” - obtain sugars and many other macromolecules from other organisms

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8
Q

Chlorophylls a and b absorb…

A

blue and red to reflect green (many membranes=more pigment)

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9
Q

Carotenoids absorb…

A

green and blue (reflect orange)

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10
Q

What does resonance allow?

A

alternating double bonds to allow molecules to absorb light

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11
Q

range of absorption provided by multiple pigments determines the _________________ of photosynthesis

A

action spectrum

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12
Q

Light rxns convert _______ energy to _______ energy.

A

light, chemical

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13
Q

Electrons from water are ________ and used to drive an _____________.

A

excited, electron transport chain

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14
Q

What is the order of a light reaction?

A

PS 2 –> ETC –> PS 1

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15
Q

Light reactions have what kind of flow?

A

noncyclic electron flow ( H20 —> NADP^+)

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16
Q

What is the reaction center of PS2?

A

P680 (absorbs 680 nm of light)

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17
Q

What is the function of PS2?

A

catalyzes oxidation of H20 —> O2

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18
Q

What is plastoquinone?

A

-lipid soluble carrier protein
- moves through membrane to transfer electrons

19
Q

What is the reaction center of PS1?

A

P700 (absorbs 700 nm of light)

20
Q

What can PS1 not do?

A

oxidize H20

21
Q

What is the final electron acceptor of photosynthesis?

22
Q

What is photophosphorylation?

A

proton motive forces drives ATP production at ATP synthase

23
Q

What is the direction of chemiosmosis?

A

lumen —> stroma (different than oxidative phos)

24
Q

Describe cyclic electron flow.

A

electrons returned to PQ and cycle between PS 1 and the ETC (increases ATP production)

25
Under what conditions would a plant use cyclic flow?
- night - aquatic plants - less water - no CO2
26
What are the 3 steps of the Calvin Cycle?
1. Fixation 2. Reduction 3. Regeneration
27
What is the fixation step of the Calvin Cycle?
- CO2 is "fixed" into useful form - CO2 attached to 5-carbon RuBP - then splits into 2 3-carbon 3PGA
28
What is the reduction step of the Calvin Cycle?
3PGA reduced to G3P
29
What is the regeneration step of the Calvin Cycle?
G3P is regenerated to RuBP
30
What is rubisco?
carbon fixation enzyme
31
Rubisco is the ___________ enzyme on earth.
most abundant
32
Why is rubisco a popular target for genetic engineering?
- improving its catalytic activity 1. increased photosynthesis for crop plants 2. remove co2 from atmosphere to combat climate change
33
What is the problem with rubisco?
- has an affinity for co2 and o2
34
What is the issue with rubisco and photorespiration?
- wastes energy and already-fixed co2 (releases co2 rather than fixing it) - decreases sugar production
35
Leaves obtain co2 through __________.
stomata
36
________ stomta = ___ > ____ = _____________
closed, o2, co2, photorespiration
37
Describe C4 plants.
- use spatial separation - plants in hot, dry climates - additional co2 fixation step in separate cell layer
38
Describe CAM plants.
- use temporal separation - desert plants - open stomata and fix co2 at night, calvin cycle during day
39
Describe carbon fixation for C3 plants.
RuBP + CO2 ---Rubisco-----> 2 3-phosphoglycerate (3-carbon organic acid)
40
Describe carbon fixation for C4 plants.
3-carbon compound + CO2 ----PEP carboxylase (separate cell layer)---> 4-carbon organic molecule
41
Describe carbon fixation for CAM plants.
3-carbon compound + CO2 ----PEP carboxylase (at night)---> 4-carbon organic molecule
42
What is the direct product of photosynthesis?
G3P!!!!!!!!!
43
What is gluconeogenesis?
almost the exact reverse of glycolysis steps 1-5.
44
After photosynthesis, glucose is then...
1. combined w fructose to make sucrose; transported o rapidly growing parts of the plant 2. polymerized to form starch for long term storage

Biology Chapter 10 (1 decks)

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