Photosynthesis

Question 1

Calvin Cycle

Answer 1

main pathway for movement of C in the biosphere

Question 2

3 stages of Calvin cycle

Answer 2

1- Fixation and Hydrolysis
2- Preparation and Reduction
3- Regeneration

Question 3

rubsico

Answer 3

enzyme used in stage one to add CO2 to RuBP to form 2x 3PG

Question 4

NADPH + ATP

Answer 4

required in stage 2 to reduce 3PG to G3P

Question 5

triose phosphate

Answer 5

3PG and G3P
One of the G3P formed is used for biosynthesis of organic molecules

Question 6

Stage 3

Answer 6

remaining 5 G3P are used to regenerate RuBP using ATP

Question 7

How much ATP and NADPH is used for one cycle

Answer 7

9ATP
6NADPH

Question 8

Methods of cycle regulation

Answer 8

-Key enzymes are only synthesized in tissues exposed to light (rubisco)
-Reduced ferredoxin, ATP, and NADPH activate cycle enzymes

Question 9

rubisco activase

Answer 9

removes inhibitory sugar-phosphate
compounds from the rubisco active site

Question 10

triose phosphate/phosphate translocator

Answer 10

catalyzes exchange or triose phosphates for Pi

Question 11

antiport system

Answer 11

exports triose phosphates if Pi for making new ones returns to the stroma

Question 12

glucose-1-phosphate

Answer 12

hexose required for starch and sucrose syntesis formed from G3P and DHAP

Question 13

S1 of G1P synthesis

Answer 13

triose –> fructose-6-phosphate (2 forms)
occurs in stroma and cytoplasm

Question 14

isoenzyme/isozyme

Answer 14

proteins that carry out the same enzymatic functions

Question 15

Stage 2 of G1P synthesis

Answer 15

F6P –> glucose-6-phosphate (G6P)

Question 16

Stage 3 of G1P syntheis

Answer 16

G6P–> G1P

Question 17

Which sugar is created in the cytosol

Answer 17

Sucrose

Question 18

Sucrose formation

Answer 18

G1P –> UDP-glucose –> fructose-6-phosphate —-> surose-6-phosphate –> sucrose

Question 19

Fructose-2,6-bisphosphate

Answer 19

regulates glycolysis by inhibiting F16BP from forming F6P

Question 20

Which sugar is created in the stroma

Answer 20

starch

Question 21

Starch synthesis

Answer 21

triose phosphate (G3P) –> glucose-1-phosphate –> ADP glucose –> starch

Question 22

starch synthase

Answer 22

adds ADP-glucose to growing starch chains

Question 23

what is rubiscos second function

Answer 23

oxygenase

Question 24

what is the result of rubiscos oxygenase reaction

Answer 24

2C phosphoglycolate that cannot be used in C cycle

Question 25

3 strategies to avoid oxygenation

Answer 25

1- photorespiratory glycolate path 2- C4 photosynthesis 3- crassulacean acid metabolism

Question 26

glycolate pathway

Answer 26

a 7 step photorespiratory pathway that takes place in leaf peroxisomes to convert phosphoglycolate to 3PG

Question 27

where does glycolate pathway occur

Answer 27

cytosol, leaf peroxisome, and mitochondria

Question 28

what are the transformations of the glycolate pathway

Answer 28

Phosphoglycolate --> glycolate --> glyoxylate --> glycine --> serine --> hydroxypyruvate --> glycerate --> 3PG

Question 29

Hatch-Slack cycle

Answer 29

short carboxylation/decarboxylization pathway

Question 30

oxaloacetate

Answer 30

intermediate in carbon fixation in the Hatch-Slack cycle

Question 31

C4 plants

Answer 31

Minimize Photorespiration by Confining Rubisco to Cells Containing High Concentrations of CO2 Utilize the Hatch-Slack cycle

Question 32

C3 plants

Answer 32

have 3PG as the first detectable product of C fixation

Question 33

What type of photosynthetic cells are found in C4 plants

Answer 33

1- mesophyll cells 2- bundle sheath cells

Question 34

mesophyll cells

Answer 34

CO2 fixation uses an enzyme that is NOT rubisco (cells exposed to CO2 and O2)

Question 35

Bundle sheath cells

Answer 35

relatively isolated from the atmosphere and the ENTIRE calvin cycle is confined to these cells

Question 36

4 steps of the HS cycle

Answer 36

1- PEP--> oxaloacetate 2- oxaloacetate--> malate 3- release of CO2 wihcih is refixed and reduced by calvin cycle 4- pyruvate --> PEP

Question 37

How many ATP do C4 and C3 plants use

Answer 37

C4 = 5ATP C3 = 3ATP

Question 38

what is the benefit of C4 plants

Answer 38

Better in hotter environments and with low CO2. Photosynthetic rate 2-3x higher than C3

Question 39

Crassulacean Acid Metabolism (CAM) plants

Answer 39

open stomata only at night to minimize water loss