Ch. 4 - Photosynthesis

Question 1

Overall reaction:

6CO2 + 6H2O -> ____ + ____

Answer 1

____
C6H12O6
6O2

Question 2

Noncyclic Photophosphorylation (ADP + Pi + light -> ____): light-dependent reaction.

Answer 2

ATP

Question 3

Noncyclic Photophosphorylation

1. Photosystem II: electrons trapped by P680 in PSII are ____ by light.

Answer 3

energized

Question 4

Noncyclic Photophosphorylation

2. ____: two excited e- passed to primary e- acceptor; primary because it is the first in chain of acceptor.

Answer 4

primary e- acceptor

Question 5

Noncyclic Photophosphorylation

3. E- transport chain: consists of a ____ which contains proteins like ____ and cofactor
   Fe2+; analogous to ____

Answer 5

plastoquinone complex (PSII)

cytochrome
oxidative phosphorylation

Question 6

Noncyclic Photophosphorylation

4. Phosphorylation: 2e- move down ETC => ____ (energy used to phosphorylate about ____).

Answer 6

lose energy

1.5 ATP

Question 7

Noncyclic Photophosphorylation

5. Photosystem I: ETC terminates with PSI (P700); they are again ____ by sunlight and passed on to
   another primary e- acceptor. From this point forward it can go to cyclic or noncyclic path.&raquo_space;»If noncyclic…

Answer 7

energized

Question 8

Noncyclic Photophosphorylation

6. NADPH: 2e- then pass down a short ETC (with proteins like ____) to combine NADP+ + H+
   + 2e- => ____ (coenzyme) (only in noncyclic?).

Answer 8

ferrodoxin

NADPH

Question 9

Noncyclic Photophosphorylation

7. Splitting of Water (____): the loss of 2e- from PSII (initially) is replaced when H2O splits into ____, ____, and
   ____.(H+ goes for ____ formation and 1⁄2 O2 that contributes to release as ____). This occurs at PSII.

Answer 9

photolysis
2e-
2H+
1/2O2
NADPH
oxygen gas

Question 10

Noncyclic Photophosphorylation

REACTION:

H2O + ADP + Pi + NADP+ + light => ____ + ____ + ____ + ____

Answer 10

ATP
NADPH
O2
H+

Question 11

Note on photosystems: few hundred in each thylakoid, have a rxn center containing chlorophyll a surrounded by ____ that funnel energy to it.

Answer 11

antenna pigments

Question 12

B. Cyclic Photophosphorylation: this replenishes ____ when Calvin cycle consumes it
- When excited 2e- from PSI join with protein carriers in the ____ electron transport chain and generate ____ as they pass through; these 2e- are recycled into PSI and can take either cyclic or noncyclic path.

Answer 12

ATP
first
1 ATP

Question 13

C. Calvin Cycle: fixes CO2, repeat ____, uses 6CO2 to produce ____ (glucose). C3 photosynthesis (____)

Answer 13

6 times
glucose C6H12O6
dark reaction

Question 14

Calvin Cycle

1. Carboxylation: 6CO2 + 6RuBP => 12PGA, ____ (most common protein in the world, aka ____)
   catalyzes this reaction. (so named because PGA is 3C).

Answer 14

Rubisco

RuBP carboxylase

Question 15

Calvin Cycle

2. Reduction: 12ATP + 12NADPH converts ____ => ____ or 12PGAL; energy is incorporated; by-products (NADP+
   and ADP) go back into ____

Answer 15

12PGA
12G3P
noncyclic photophosphorylation

Question 16

Calvin Cycle

3. Regeneration: 6ATP convert ____ => ____ (allows cycle to repeat).

Answer 16

10G3P

6RuBp

Question 17

Calvin Cycle

4. Carbohydrate synthesis: 2 remaining ____ are used to build glucose.
   ____ + 18ATP + 12NADPH + H+ => 18ADP + 18Pi + 12NADP+ + ____

Answer 17

G3P
6CO2
1 glucose (2G3P)

Question 18

Calvin Cycle

5. This is the “dark reaction”, but it cannot occur w/out light because it is dependent on the ____
   produced from the light rxn (____ and ____)

Answer 18

high energy molecules
ATP
NADPH

Question 19

Calvin Cycle

Note: Bootcamp says that the energy used to drive the light-independent rxns comes from ____. ____ is what drives photosynthesis! And the energy in glucose traces back to ____ that gets stored in the form of glucose ____! Remember, plants do have mitochondria that make ATP, BUT: the ATP from photosynthesis comes from the ____ (not mitochondria) and is used to drive photosynthesis further (Calvin cycle). Photosynthesis primarily makes glucose for the plant’s own ____ to use as energy! Still need mitochondria for plant tissues but they don’t make the ATP for ____, and photosynthesis ATP isn’t used for general cell fxn!

Answer 19

light (photons)
light energy
light
chemical bonds
chloroplast
mitochondria
photosynthesis

Question 20

D. Chloroplast: ____ and ____ reactions occur. (____ like mito + nucleus)

Answer 20

light-dependent
light-independent
double membrane

Question 21

D. Chloroplast

1. ____: plasma membrane (phospholipid bilayer)
2. ____
3. ____: also phospholipid bilayer.
4. Stroma: fluid material that fills area inside inner membrane; ____ here (fixing ____ => ____)

Answer 21

outer membrane
intermembrane space
inner membrane
calvin cycle
CO2
G3P

Question 22

D. Chloroplast

5. Thylakoids: suspended within ____ (stacks); individual membrane layers are ____; entire stack is ____ membrane of thylakoids contain (PSI + PSII), cytochromes, and other e- carriers. Also phospholipid bilayer.
6. Thylakoid lumen: interior of the thylakoid; ____ accumulates here.

Answer 22

stroma
thylakoids
granum
H+

Question 23

D. Chloroplast

Note: Gradient uses ATP synthase to move the accumulated H+ from ____ to ____; H+ move from in to out to generate ATP via synthase……….

whereas in ox-phos we build up H+ ____ and then shuttle it back in to mitochondria to generate ATP via synthase

Answer 23

thylakoid membrane
stroma

outside

Question 24

D. Chloroplast

Locations:
noncyclic photophos takes place in ____.

Cyclic phos takes place on ____ (pieces connecting the ____).

Photolysis takes place inside the ____ (passes e- to the membrane for noncyclic photophos).

Answer 24

thylakoid membranes
stroma lamellae
thylakoids

thylakoid lumen

Question 25

D. Chloroplast Calvin Cycle takes place in the ____. Chemiosmosis takes place across the ____. All of these take place ____ the chloroplast! Remember that is the ____, not the outer/inner chloroplast membranes, that absorb light!

Answer 25

stroma thylakoid membrane inside thylakoid membrane

Question 26

E. Chemiosmosis in Chloroplasts: uses ____ gradient to generate ATP.

Answer 26

H+

Question 27

E. Chemiosmosis in Chloroplasts 1. H+ ions accumulate inside ____: H+ are released into ____ when ____ is split by PSII. H+ is also carried into lumen from stroma by ____ between PSII and PSI.

Answer 27

thylakoid lumen H2O cytochrome

Question 28

E. Chemiosmosis in Chloroplasts 2. A pH and electrical gradient is created: about ____.

Answer 28

pH 5

Question 29

E. Chemiosmosis in Chloroplasts 3. ATP synthase generates ATP: phosphorylate ADP + Pi => ATP. (____ is required for 1ATP).

Answer 29

3H+

Question 30

E. Chemiosmosis in Chloroplasts 4. Calvin cycle produces ____ using NADPH & CO2 & ATP: at the end of e- transport chain following PSI, 2e- produces ____.

Answer 30

2 G3P | NADPH

Question 31

F. Photorespiration: fixation of ____ by ____ (can also fix ____) => produces no ATP or sugar. Rubisco is not ____ because it will fix both ____ and ____ at the same time if both are present. Probably arose because early earth atmosphere didn’t have much ____ so it didn’t matter. ____ breakdown the products of this process (w/ Rubisco).

Answer 31

oxygen rubisco CO2 efficient CO2 O2 O2 peroxisomes

Question 32

G. C4 Photosynthesis: evolved from ____, when CO2 enters leaf; absorbed by ____ (then moved to ____); instead of being fixed by rubisco into PGA, CO2 combines with ____ to form ____ by ____ (in mesophyll)

Answer 32

C3 mesophyll cells bundle sheath PEP OAA PEP carboxylase

Question 33

G. C4 Photosynthesis - OAA has 4C => C4 photosynthesis. - OAA => ____ and then transported through ____ into ____ - Malate => pyruvate + CO2. (CO2 can be used into Calvin cycle) (Pyruvate moved back to ____ then => PEP)

Answer 33

malate plasmodesmata bundle sheath cell mesophyll

Question 34

G. C4 Photosynthesis - Overall purpose is to ____ to ____ (structure = Kranz anatomy, process = Hatch- Slack pathway (little O2 presence reduces competition while rubisco is fixing). Minimize ____ and ____ loss from stomata (leaf pores); found in ____ climates (faster fixation speed and more efficient). Requires one additional ____ (which becomes AMP). C3 typically occurs in ____, but in C4 it occurs in ____. Corn, sugarcane

Answer 34

mesophyll bundle sheath cell photorespiration H2O hot, dry ATP mesophyll bundle sheath cells

Question 35

H. CAM Photosynthesis: - Another add-on to C3, ____; almost identical to C4.

Answer 35

crassulacean acid metabolism

Question 36

H. CAM Photosynthesis 1. PEP carboxylase fixes CO2 + PEP to OAA; OAA => ____. 2. MA is shuttled into ____ of cell.

Answer 36

malic acid | vacuole

Question 37

H. CAM Photosynthesis 3. At night, stomata are ____ (opposite of normal), PEP carboxylase is ____, malic acid ____ in vacuole. 4. During day, stomata are ____. Malic acid is ____ of vacuole and converted back to OAA (require ____), releasing ____ (moved onto ____ with rubisco) and PEP.

Answer 37

open active accumulates ``` closed out 1 ATP CO2 calvin cycle ```

Question 38

H. CAM Photosynthesis - Overall advantages are can proceed during day while stomata are closed (reduce ____). Cacti, crassulacea plants,

Answer 38

H2O loss

Question 39

- As leaves age, chlorophyll ____ to extract valuable components like ____, carotenoids are ____.

Answer 39

breaks down Mg2+ visible

Question 40

- Splitting of H2O provides 2e- for noncyclic photophosphorylation; incorporated into ____ and ____.

Answer 40

NADPH | Calvin cycle

Question 41

- Calvin cycle is light-independent, but it requires ____ and ____ produced from light-dependent rxn.

Answer 41

ATP | NADPH (produced from LIGHT)

Question 42

____ (chlorophyll b, carotenoids, phycobilins [red algae pigment], xanthophylls) capture wavelegnths that ____ does not, passes energy to chlorophyll a where ____ occurs. Chlorophyll a has ____ (alternating double and single bonds, double bonds critical for light rxns) complexed w/ ____ inside.

Answer 42

antenna proteins chlorophyll a direct light rxn porphyrin ring Mg atom