C1.3 Photosynthesis Flashcards

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1
Q

Rubisco

A

An enzyme that catalyses the addition of carbon dioxide to RuBP during the Calvin cycle
(It is the most abundant enzyme on Earth)

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2
Q

Steps of the calvin cycle

A
  1. Carbon fixation
  2. Reduction of Glycerate 3 phosphate
  3. Regenration of RUBP
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3
Q

What goes into light dependent reaction

A

light and water

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3
Q

What comes out of light dependent reaction

A

oxygen

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4
Q

What goes into calvin cycle

A

CO2

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5
Q

what comes out of calvin cycle

A

glucose

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6
Q

What is made in light dependent reaction that goes into calvin cylce

A

ATP and NADPH

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7
Q

What is made in calvin cycle that goes into light dependent reaction

A

ADP + P and NADP

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8
Q

Calvin cycle

A

Cyclic set of reactions fixing CO2 to produce glucose and replenish RuDP

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8
Q

Light dependent reaction

A

The initial stages of photosynthesis that occur in the thylakoid membranes of chloroplasts.
* utilise light energy to convert ADP and Pi into ATP, and reduce NADP to reduced NADP
* also generate oxygen through the process of photolysis.

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9
Q

Action Spectrum

A

A graph displaying the overall rate of photosynthesis (y)against the wavelength of visible light (x)

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10
Q

Absorption Spectrum

A

A graph displaying the wavelength of light absorbed by a particular pigment

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11
Q

What happens in the light dependent reactions of photosynthesis (in very short)

A

A proton gradient is generated thylakoid space

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12
Q

A product from the light dependent reactions which is not needed for the light independent reactions

A

oxygen

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13
Q

Photolysis

A

The break down of water to form oxygen, hydrogen and electrons

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14
Q

Light independent reaction

A

The second stage of photosynthesis.
* occur in the stroma of chloroplasts
* involve the fixation of carbon dioxide
* production of carbohydrates using the ATP and reduced NADP generated in the light-dependent reactions

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15
Q

Pigment

A

Chemical substances that absord different wvalengths of light and appear coloured to us

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16
Q

Why do leaves look green

A

all other wavelnegths of colored light are absorbed besides green light

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16
Q

Visible light range

A

380-750 nm

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16
Q

Types of pigments

A
  • carotenoids
  • chlorophyll A
  • chlorophyll B
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17
Q

Carotenoids

A

good absorber of purple- blue
appears orange/yellow

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18
Q

Chlorphyll A

A

good absorberof purple-dark blue & yellow-orange

appears green

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19
Q

Chlorophyll B

A

good absorber of blue yellow
appears green

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20
Q

Action Spectrum

A

A graph displaying the overall rate of photosynthesis at different wavelengths

21
Q

Absorption Spectrum

A

A graph displaying the absorption of different wavelengths by pigments

22
Q

co2 enrichment

A

FACE
* CO2 levels are elevated by burning fossil fuels => all other conditions controlled
* total biomass produced measured/ yield of fruits produced

enclosed green house
* CO is released in a closed environment continuously
* total biomass prodcued is measured/ yield of vegetables grown

23
Q

What is used to reduce NADP in the light dependent reactions of photosynthesis

A

electrons from PS1

24
Q

Lollipop experiment

A

calvin utilises radioactive carbon to trace the path of carbon through photosynthesis

  • algae were analyzed by chormatography to seperate carbon compounds
  • determined order of which carbon compounds were produced
    *
25
Q

Which space has the highest H+ concentration in a chloroplast

A

Thylakoid space/intermembrane space of thylakoids

26
Q

Where is ATP synthase located

A

inner memebrane space (auf den fühlern)

27
Q

what is the stationary phase in thin layer paper chromatography

A

silica gel, aluminium oxide, cellulose

28
Q

Photorespiration

A

is a process that occurs in plants, especially under hot, dry conditions, in which rebusco binds to O2 instead of CO2

(it can reduce the efficiency of photosynthesis)

29
Q

Photorespiration mechanism

A
  • Rubisco binds to O2 instead of CO2 using
  • uses energy and oxygen to prodcue small amounts of CO2 instead of making sugars
  • makes no ATP & Sugar
30
Q

C4 and CAM plants

A
  • adapted mechanisms to reduce photorespiration
  • have specialized pathways that concentrate CO₂ near Rubisco, making it more likely that Rubisco will bind to CO₂ rather than O₂
  • (even under low CO₂ conditions)
31
Q

Photoactivation

A

In photosynthesis the process at which a photochemical reaction occurs, resulting in an excited electron

32
Q

Photolysis equation

A

2H2O -> 4e + O2 + 4H+

33
Q

Steps of chromatography of chloroplasts

A
  1. crush leaves using propanone/acetone to dissolve pigment
  2. place spot of pigment at the bottom of the chromatography paper
  3. dip it
  4. as solvent passes through, it will seperate out the pigment into different layers as they travel at different rates across the paper
  5. calculate rf value
34
Q

components within a choloroplast

A
  • stroma
  • double membrane
  • thylakoid
  • granum
  • lamella
35
Q

Stroma

A

cytoplasm of chloroplasts (contains enzymes and ideal ph)

36
Q

Thylakoid

A

Has ETC and ATP synthase for photophosphorylation

37
Q

Lamella

A

connects and seperates thylakoid

38
Q

Chloroplast

Double membrane

A

evidence for endosymbiosis

39
Q

Why thin layer chromotography is better

A
  • utilises sillica gel/aluminium oxide
  • gives better result 8dots are more defined)
40
Q

cyclic phosphhorylation

A
  • Occurs when NADPH is accumulating
  • light energy causes the excitation of electrons from PSI
  • electrons move along ETC, pumping H ions through membrane proteins
  • H generate ATP using ATP synthase
  • electrons return to PS1 after moving along ETC -> regain energy

=> cyclic as electrons return to PS1 continuously after eveery cycle
=> NO NADPH is produced as the electrons keep getting recycled

41
Q

non cyclic phosphorylation

A
  • after the electrons released from PS2; along ETC; pump H ions onto PS1
  • electrons are reexcited by light energy absorbed by PS1 => passes along proteins
  • final protein acceptor = ferrodoxin
  • electrons from ferrodoxin go to NADP reductase= H ions make NADPH

=> non cyclic because electrons dont get recycled = NADP takes them to make NADPH

42
Q

Differences between cyclic & non cyclic phosphorylation

A

Cyclic
* involves PS1 only
* only produces small amount of ATP
* does not produce NADPH
Non cyclic
* involves both PS1 & PS2
* reaches final protein = ferrodoxin & reduces NAD+ produces ATP, NADH and O2
* electrons aren’t recycled

43
Q

The great oxidation event

A

explains how 2.4 Billion years ago, photosynthesis began to happen in cyanobacteria which drastically increased the oxygen levels in the atmosphere

44
Q

carbon fixation

A

The conversion of inorganic carbon (CO2 from atmosphere) to organic carbon by a living organism

45
Q

carboxylation

A

The process of adding a carboxyl group from a molecule forming a molecule of carbon dioxide

46
Q

How are the proton concentrations within layers of the chloroplast

A

Stroma = low concentration of H+
Thylakoid intermembrane space = high H+

47
Q

What do you need ATP and NADH for in the 2nd step of the calvin cycle

A

ATP = provide energy for the reduction of G3P
NADH= provide hydrogne ions to reduce G3P to trios phosphate

48
Q

Where do the products produced go after the light dependent stage? How does this relate to where the proton gardient builds up?

A
  • products go to calvin cycle => in stroma
  • protons are pumped into thylakoid space => then move down conc. gradient through ATP => into stroma where they need to be used
49
Q

Photophosphorylation explained

A
  • Photophosphorylation is thr production of ATP
  • light shines onto PS2 (680nm) and is absorbed by the accessory pigments
  • light contributes to photolysis splitting water into Hydrogen ions, oxygen gas and e-
  • ETC moves electrons through a series of carriers in thylakoid membrane
  • electrons provide energy to pump hydrogen ions from stroma into thylakoid space
  • small thylakoid space nehances high proton conc. built
  • hydrogen ions move by diffusion through ATP synthase to generate ATP
  • ATP is generated by adding Pi to ADP
50
Q

outline light intensity as a factor

A
  • as it increases, the rate of photosynthesis increases
  • until a plateau reached at higher light imtensities
  • when another factor is now limiting
  • light is needed for light dependent reactions in thylakoid membrane
51
Q

outline temperature as a factor

A
  • as it increases, rate of photosynthesis increases
  • to an optimum temperature above which rate stops
  • temperature affects enzymes (example rubsico in calvin cycle)
  • causes them to denature = rate rapidly decreases
52
Q

outline carbon dioxide as a factor

A
  • increases, increases rate of photosynthesis
  • until plateau is reached at higher CO2 conc. when another factor is limiting
  • CO2 needed for light independent reactions (Calvin cycle)
53
Q

outline photoactivation

A
  • photon absorbed by pigment molecules in chlorophyll
  • electrons are passed to chlorophyll molecules at the reaction centre
  • causes electron to be raised to higher energy level
  • electron is passed along chain of carrier molecules in PS2
54
Q
A