Lectures 8-9-10-11

Question 1

which cells are the most active photosynthetic cells? Where is the primary site of photosynthesis

Answer 1

mesophyll cells

Question 2

mesophyll cells contain [blank] which contain [blank]

Answer 2

chloroplasts, chlorophylls

Question 3

Photosynthesis occurs in two stages (2 reactions)

Answer 3

Thylakoid reactions and carbon fixations reactions

Question 4

What happens in the thylakoid reactions

Answer 4

ocurs in the internal membrane of chloroplasts,

Question 5

production of thylakoid reactions

Answer 5

ATP and NADPH

Question 6

thylakoid reactions are light [blank]

Answer 6

dependent

Question 7

calvin reactions/carbon fixation are dark reactions and are light [blank]

Answer 7

independent

Question 8

carbon fixation reactions occur where and produce what

Answer 8

stroma, produce sugars

Question 9

formula for reaction

Answer 9

6co2 + 6h20 —> c6h12o6 + 6o2

Question 10

water is [blank] to release [blank], co2 is [blank] to form [blank]

Answer 10

oxidized to release oxygen, reduced to form sugars

Question 11

Wavelength

Answer 11

distance between wave crests

Question 12

frequency

frequency (v)

Answer 12

number of crests passing

Question 13

Energy (E)

Answer 13

depends on frequency

Question 14

explain E=Hv

Answer 14

Energy is equal to Planck’s constant x frequency

Question 15

light behaves as a wave and as a photon

Question 16

explain c = lambda v

Answer 16

c is the speed of the wave = wavelength x frequency

Question 17

visible spectrum of light absorption of chlorophyll is from

Answer 17

400 to 700

Question 18

when chlorophyll absorbs a photon, what happens

Answer 18

it transitions to a higher excited state (higher when absorbing blue light than red)

Question 19

excited energy can be dissipated in 4 ways

Answer 19

-Fluorescence (re-emitting as light),
-Heat loss,
-Energy transfer to other molecules,
-Photochemistry to drive reactions.

Question 20

chlorophyll a and b absorb what light and reflect what light

Answer 20

red and blue light, reflect green, so theyre found in green plants

Question 21

chlorphyll c and d are found in what type of organisms

Answer 21

protists/ cynaobacteria

Question 22

structure of chlorophyll

Answer 22

prophyrin ring and hydrocarbon tail

Question 23

accesory pigments like carotenoids absorb what color, at what wavelength

Answer 23

orange to yellow, at 400 to 500 nm

Question 24

structure of carotenoids molceularly

Answer 24

linear with many double bonds

Question 25

carotenoids transfer absorbed light energy to

Answer 25

chlorophyll

Question 26

some light energy absorbed by chl is stored as

Answer 26

chemical bonds

Question 27

[blank] serves as antenna complexes

Answer 27

pigments

Question 28

Antennae complexes absorb light and transfer energy to [blank] centers, where it’s used for [blank] reactions to [blank]

Answer 28

reaction, redox, store long term energy

Question 29

Each reaction center is associated with an [blank]

Answer 29

antenna complex

Question 30

Quantum yield (Φ) is defined as the number of

Answer 30

photochemical products divided by the number of quanta absorbed.

Question 31

explain a 0, 1, and 0.95 quantum yield

Answer 31

0 = process does not respond to light
1 = every absorbed photon contributes
0.95 = dim light, fluorescence at 0.95

Question 32

how is atp and nadph in light reactions form

Answer 32

redox reaction - electrons are transferred to nadp+ which reduces it to nadph

Question 33

nadph and atp are made from [blank] reactions and use to drive [blank]

Answer 33

light, carbon fixation

Question 34

action spectrum shows what

Answer 34

the response of a biological system to light as a function of wavelength

Question 35

in the light reactions, for every 2 molecules of water split, how many nadp+ and nadph are release

Answer 35

2 nadp+ reduced to make 2 nadph, every 2 molecules of water releases one O2

Question 36

many compounds serve as an artificial electron acceptor in the [blank] reaction

Answer 36

Hill

Question 37

PSII functions best with which wavelength? Does it work well with far-red? What does it produce

Answer 37

best with red light, 680 nm, produces strong oxidants (WEAK REDUCTANT) to split water and release O2

Question 38

PSI prefers red or far-red? What wavelength? What does it produce?

Answer 38

Functions with far-red light (~700 nm or greater than 680), producing strong reductants (weak oxidants) (NADPH), can reduce NADP+

Question 39

explain red drop effect

Answer 39

sudden decrease in photosynthetic efficiency when plants are exposed to light with a wavelength longer than 680 nm (in the far-red region).

Why does this happen?

Photosystem II (PSII) operates most efficiently at a wavelength of around 680 nm, which is why it’s called P680. If the light provided to the plant is only longer than 680 nm (like far-red light), it primarily excites Photosystem I (PSI, which absorbs best at 700 nm, hence called P700).

When only PSI is activated, the electron transport chain doesn’t operate efficiently, and ATP and NADPH production declines, leading to a drop in the rate of photosynthesis.

Question 40

explain the emerson enhancement effect

Answer 40

Emerson observed that when plants are exposed to both red light (around 680 nm) and far-red light (greater than 680 nm) simultaneously, the photosynthetic rate increases significantly compared to using either wavelength alone, optimizing the flow of electrons through the electron transport chain and enhancing the production of ATP and NADPH

Question 41

The [blank] is a model that describes the flow of electrons through the two photosystems, Photosystem II (PSII) and Photosystem I (PSI), during the light-dependent reactions of photosynthesis.

Answer 41

Z scheme

Question 42

The Z-scheme captures the movement of electrons from [blank] to [blank], forming NADPH through a series of redox reactions.

Answer 42

water to napd+

Question 43

The two photosystems are responsible for [blank] and driving the [blank] to create ATP and NADPH, which are then used in the Calvin Cycle.

Answer 43

capturing light energy, electron transfer

Question 44

Which equation is this for:
2H2​O→4H+ +4e− +O2​

Answer 44

photolysis of water in PSII
- releases electrons (4) that replace the ones that were lost in 680
- releases oxygen
- release protons for gradient

Question 45

Electrons from P680 (PSII) are transferred to [blank], which then transports them to the [blank].
As the electrons move through the cytochrome complex, they drive the pumping of [blank] into the [blank]. This builds up a proton gradient that will later be used to produce ATP.

Answer 45

plastoquinone (PQ), cytochrome b6f complex, protons, thylakoid

Question 46

what does PSI do, in terms of pc or pq, etc

Answer 46

PSI absorbs photons, exciting electrons in the P700 chlorophyll molecule to an even higher energy state.

Electron Replacement: The electrons lost from P700 are replaced by the electrons coming from PSII 680.

Electrons carried via plastocyanin (PC).

The excited electrons from P700 are passed down to a protein called ferrodoxin (Fd).

From there, the electrons are transferred to NADP⁺ reductase, which reduces NADP⁺ to NADPH.

Question 47

how is atp made from psI and psII

Answer 47

The movement of electrons from PSII to PSI results in a proton gradient (H⁺) across the thylakoid membrane.

This gradient is used by the enzyme ATP synthase to convert ADP into ATP via chemiosmosis.

Question 48

PSI transfers proteins into [blank] lamellae

Answer 48

grana

Question 49

PSII tranfers proteins into [blank] lamellae

Answer 49

stroma

Question 50

plastocyanin (PC) is blue-colored copper, and is used in which photosytstem

Answer 50

PSI

Question 51

Plastoquinone is used in which photosystem

Answer 51

PSII

Question 52

PSII is easily damaged by

Answer 52

excess light