BIOL130 > module 8 > Flashcards

module 8 Flashcards

photosynthesis (60 cards)

Study These Flashcards
1
Q

what is photosynthesis

A

conversion of light energy to chemical energy

photosynthetic organisms build carbs using sunlight and CO2 from air

major entry point of energy into biological systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how much of the sun’s output is outside the visible range and unavailable for photosynthesis

A

60%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how far does photosynthesis occur in the ocean

A

about 100m deep -> photic zone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what kind of reaction is photosynthesis overall? what is being reduced and what does it produce?

A

redox:

CO2 is reduced to form high energy carb molecules, which requires energy in the form of sunlight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the 2 stages of photosynthesis?

A

light capture

carbon fixation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the electron donor for both parts of photosynthesis? what does the oxidation of this molecule result in?

A

H2O

produces: electrons, protons and oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the chemical reaction equation for photosynthesis

A

energy + 6CO2 + 12H2O ->

C6H12O6 + 6O2 + 6H2O

carbon dioxide -> glucose = reduction

water -> oxygen = oxidation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how are oxidation and reduction in photosynthesis linked?

A

thru the photosynthetic electron transport chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

where does photosynthesis take place in eukaryotes

A

chloroplast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the center of the chloroplast called, and what does it contain

A

thylakoid -> highly folded flattened membrane sacs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is a thylakoid

A

centre of chloroplast, highly folded flattened membrane sacs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is a chloroplast

A

semi autonomous and self-replication, bound by 2 membranes separated by narrow spac

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is a lumen

A

fluid filled space in space inside thylakoid membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the space inside the thylakoid membrane

A

lumen -> fluid filled space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the orderly stacks of thylakoids called

A

grana

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are grana

A

orderly stacks of thylakoids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the space surrounding thylakoids called

A

stroma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the stroma

A

space surrounding thylakoids - where carbon fixation occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are the 2 series of reactions in photosynthesis

A
  1. light dependent reaction:
    - sunlight energy converted into chemical energy (thylakoid membrane)
    - products: ATP and NADPH
  2. light independent reaction:
    - ATP and NADPH used to synthesize carbs (stroma)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are ways to return a cell to ground state from excited

A
  1. dissipate energy as heat
  2. re-emit energy in a longer wavelength -> fluorescence
  3. transfer energy to another molecule -> happens with photosynthetic pigments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how is light absorbed

A

energy from sun is form of electromagnetic radiation, travels in photons

when photons are absorbed, compound is higher energy (excited state)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are pigments?

A

molecules that contain chromophore -> chemical grp capable of absorbing light of specific wavelengths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

why are plants green?

A

chlorophyll is poor at absorbing green wavelength (visible light), and therefore diffuse reflected from plant’s cell walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is chlorophyll

A

major light capturing molecules

absorb light of clue/red wavelengths, reflecting green

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
what are the 2 parts of chlorophyll?
1. polyphorin ring-> light absorption - specific atom in center of ring: Mg - different side grps on ring: gives diff types of chlorophyll 2. phytol side chain - insertion of chlorophyll in lipid bilayer -> thylakoid membrane
23
what is the purpose of accessory pigments
increase efficiency of light absorption protects photosynthetic components from damage
24
what are accessory pigments
found in thylakoid membrane (ex. carotenoids) can absorb light from regions of visible spectrum that are poorly absorbed by chlorophyll
25
how does chlorophyll absorb light
an electron is elevated to a higher-energy state if it is beside other molecules, energy can be transferred energy is transferred until it reaches a pair of chlorophyll molecules (reaction centre)
26
do the antenna chlorophylls transfer energy or the electrons?
antenna chlorophylls
27
what is a reaction center chlorophyll
specific chlorophyll capable of transferring electrons to an electron acceptor
28
before the reaction center can take in more light energy, what must it do?
acquire an electron from an electron donor since it lost one electron -> H2O
29
what are photosystems
protein-pigment complexes that absorb light -> light drives redox rxns
30
what are the 2 photosystems and what do they do
photosystem ii (psii) photosystem i (psi)
31
what is photosystem ii (PSII)
one of the photosystems light absorption by PSII allows electrons pulled from water to enter photosynthetic electron transport chain, the energy level drops as it goes through the etc
32
how are the 2 photosystems connected
photosynthetic electron transport chain
32
what is photosystem i (PSI) role in photosynthesis
second input of light energy by PSI produces electron donor molecules capable of reducing NADP+
33
what products are produced from the photosystems? what role do they play in the rest of photosynthesis
create atp and nadph, energy sources needed to synthesize carbs from CO2 in the calvin cycle
34
where do H+ ions move as electrons move along the Z pathway
moved from stroma to inner compartment of thylakoids, setting up a proton gradient
34
how many reaction center chlorophyll are in each photosystem
1!
35
what is the Z scheme
the energy trajectory between PSII and PSI resembles the shape of a horizontal Z
36
what is the proton concentration of a chloroplast as photosynthesis occurs
up in lumen of thylakoid down in stroma
36
what is the flow of electrons between the photosystems
1. between H2O and PSII 2. between PSII and PSI (ETC) 3. between PSI and NADP+
37
is ATP only produced in the chloroplast in plants?
no, plants also have mitochondria to produce ATP needed elsewhere as ATP produced in the chloroplast STAYS in the chloroplast
37
what is plastoquinone
carries electrons from PSII to cytochrome b6f complex
37
how is ATP produced in the chloroplast, what is this ATP used for?
thylakoid membrane has embedded ATP synthase enzymes ATP produced remains in chloroplast to be used in carbon fixation rxns
37
what is the cytochrome-b6f complex
where electrons pass through between PSII and PSI
38
what is plastocyanin
carries electrons from cytochrome b6f complex to PSI by diffusing thru thylakoid lumen
39
how is ATP formed with the photosynthetic ETC
results from electrons moving thru PSII and PSI H+ ions (protons) are moved from stroma to lumen, creating a proton gradient, driving ATP formation by passing thru ATP synthase
40
what is the role of the Calvin Cycle
takes a low potential energy carbon compound (CO2) and converts it into a higher energy carbon compound
41
what does the calvin cycle require to operate?
NADPH and ATP which provide energy for the chemical reactions needed to synthesize carbs from CO2
42
how many chemical reactions synthesize carbohydrates from CO2 in the calvin cycle
15
43
what are the 3 categories of the reactions in the calvin cycle (steps of the calvin cycle)
1. carboxylation 2. reduction 3. regeneration
44
what is the first step of the calvin cycle? what occurs?
1. carboxylation CO2 is added to RuBP (5 carbon) to form a 6 carbon compound. this reaction is catalyzed by rubsico the product is then broken down into 2x 3 carbon molecules of PGA
45
what is the second step of the calvin cycle?
2. reduction potential energy of PGA is increased by being reduced reduction occurs in 2 steps: i. PGA is phosphorylated by ATP -> creates triose phosphates ii. triose phosphates are then reduced by NADPH, then exported out of chloroplast
46
what is the third step of the calvin cycle?
3. regeneration for every 6 triose phosphates, only 1 can be withdrawn from calvin cycle -> because RuBP needs to be regenerated using other triose phosphates regeneration requires energy (ATP) produces 3 RuBP molecules to be used in first step
47
what happens to excess carbs produced in the calvin cycle?
converted into storage: starch starch produced during the day can be used as a source of carbs during the night when there is no sunlight
48
how many photosystems did early photosynthetic bacteria have?
1 -> cannot capture enough energy
49
what are the 2 possibilities of the evolution of photosystems
1. horizontal gene transfer (PSII from one, PSI from another -> one w/ PSII & PSI) 2. gene duplication and divergence of 1 of the genes (PSII was duplicated in a single cell)
50
what were the first organisms to use water as the electron donor
cyanobacteria
51
what does the endosymbiotic theory propose?
a cyanobacterium was engulfed by a eukaryotic cell over time, it lost the ability to live outside the host thus becoming an organelle - the chloroplast
BIOL130
flashcards
Decks in class (11)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions