Photorespiration (Exam 2)

Question 1

Why does photorespiration occur?

Answer 1

O2 (instead of CO2) is fixed by Rubisco to RUBP

Question 2

how often does photorespirtion occur?

Answer 2

20-25% of the time

Question 3

when the calvin cycle evolved,

Answer 3

O2 concentrations were low

Question 4

3.2 bya =

Answer 4

no free O2 in the atmosphere

Question 5

increase temp =

Answer 5

increase oxygenase rxn (rubisco)

Question 6

(in photoresp) plant recovers 3PGA from

Answer 6

phosphoglycolate thats made in the process (photoresp) & uses 1 net ATP

Question 7

photoresp requires

Answer 7

3 organelles:

1. ) chloroplast
2. ) peroxisome
3. ) mitochondria

Question 8

photoresp slows down

Answer 8

photosynthesis & uses ATP

Question 9

photoresp becomes more common @

Answer 9

high temperatures (>30* C)

Question 10

C4 plants virtually eliminate

Answer 10

photorespiration by concentrating CO2 in the bundle sheath cells

Question 11

budle sheath cell =

Answer 11

where calvin cycle occurs

Question 12

C4 chloroplasts have fewer

Answer 12

numbers of thylakoids

Question 13

draw the photorespiration cycle

Answer 13

plzzzzz

Question 14

in C4 plants, light reactions occur in

Answer 14

mesophyll cells

Question 15

(C4) the first product of fixation =

Answer 15

oxaloacetate (OAA) (4 carbons)

Question 16

(C4) how is OAA made?

Answer 16

bicarbonate (HCO3-) is fixed to PEP in the cytoplasm of mesophyll cells to make OAA

Question 17

C4 rxns require

Answer 17

the use of ATP

Question 18

C4 rxns lose

Answer 18

2 phosphates

Question 19

C4 plant examples

Answer 19

corn, sugarcane, euphorbia, portuluca

Question 20

C4 plants are active

Answer 20

in hot weather (temperate or tropical)

Question 21

C4 plants evolved

Answer 21

30 mya

Question 22

when C4 plants evolved

Answer 22

CO2 was so low

Question 23

C4 plant %

Answer 23

1% of land plants

Question 24

C4 plants separate

Answer 24

initial carbon fixation & light-dep rxns from calvin cycke

Question 25

anatomy of C4 leaves

Answer 25

Kranz “wreath” anatomy

Question 26

(In C4) bundle sheath cells carry out

Answer 26

calvin cycle (light indep rxns)

Question 27

(In C4) mesophyll cells carry out

Answer 27

light dep rxns + C4 rxns (first fixation event in cytoplasm)

Question 28

draw C4 reaction scheme

Answer 28

plzzzzz

Question 29

CAM aka

Answer 29

Crassulacean Acid Metabolism

Question 30

CAM first noted in

Answer 30

Kalanchoe

Question 31

CAM utilizes __ ________, but…

Answer 31

C4 fixation, but occurs at night

Question 32

CAM converts

Answer 32

OAA to malate (or other C4 acids) & is stored in the vacuole of the mesophyll cell overnight

Question 33

why do CAM plants store malate overnight?

Answer 33

to reduce transpiration

Question 34

(CAM) during the day…

Answer 34

stomata are closed & the C4 acids are moved from the vacuole to the cytoplasm where they are decarboxylated (CO2 in released)

Question 35

(CAM) in the morning

Answer 35

CO2 concentrations are high

Question 36

(CAM) in the afternoon

Answer 36

photorespiration can occur

Question 37

(CAM) during the day

Answer 37

(CAM) calvin cycle & light-dep rxns occur

Question 38

do CAM plants have Kranz anatomy?

Answer 38

NO

Question 39

(CAM) C4 rxns in

Answer 39

photosynthetic chlorenchyma

Question 40

(CAM) rxns all occur

Answer 40

in the same cell!

Question 41

(CAM) plants live in

Answer 41

arid environments or microsites

Question 42

(CAM) plant examples

Answer 42

mostly tropical epiphytes (grow on other plants but are not parasites)
agave, orchids, cactus, tillandsia, bromeliads