photosynthesis

Question 1

photosynthesis

Answer 1

light energy from the sun is used to synthesized glucose

Question 2

overview of photosynthesis

Answer 2

• chlorophyll A,B + carotenoids absorb energy from sunlight
• photons excite electrons
• excited electrons are unstable and re-emit energy
• energy absorbed by chlorophyll A molecules, P680 (PSII) + P700 (PSI)

Question 3

what does chlorophyll A have?

Answer 3

porphyrin ring with Mg2+ atom inside

Question 4

chloroplast anatomy (8)

Answer 4

intermembrane space
outer membrane
inner membrane
granum
thylakoid lumen
stroma
stroma lamellae
thylakoid membrane

Question 5

granum

Answer 5

stacks of thylakoids

Question 6

thylakoid lumen

Answer 6

location of photolysis
H+ ions accumulates here because of the ETC

Question 7

stroma

Answer 7

location of the calvin cycle

Question 8

stroma lamellae

Answer 8

location of the cyclic photophosphorylation

Question 9

thylakoid membrane

Answer 9

location of the ETC
structure which absorbs light

Question 10

light reaction

Answer 10

1. electrons trapped by PSII are energized by light
2. 2 excited electrons are passed to a primary electron acceptor and move through the ETC
3. these 2 electrons lose their energy which is used to form ~1.5 ATP

Question 11

where does the ETC end

Answer 11

PSI&raquo_space; electrons are re-energized and passed to a different primary electron acceptor which can now go through the cyclic or non-cyclic path

Question 12

cyclic phosphorylation

Answer 12

• 2 electrons from PSI go back through the 1st ETC and generate 1 ATP
• these 2 electrons are recycled into PSI and can either go through cyclic or non-cyclic pathway again

Question 13

non-cyclic phosphorylation

Answer 13

• 2 electron go through an ETC and combine with NADP+ and H+ to form NADPH
• this NADPH is used in the calvin cycle to create glucose

Question 14

dark reaction is also known as

Answer 14

calvin cycle

Question 15

what is purpose of dark rxn

Answer 15

fixes carbon dioxide into glucose
CO2&raquo_space; 2 G3P

Question 16

4 steps of dark rxn

Answer 16

1. carboxylation = 6CO2 + 6RuBP&raquo_space; 12PGA
   catalyzed by enzyme RuBisCo
2. reduction = 12 PGA (with 12 ATP + 12 NAPH)&raquo_space; 12 G3P or 12PGAL
   byproducts NADP+ & ADP go to non-cyclic photophosphorylation
3. regeneration = 10 G3P (with 6 ATP)&raquo_space; 6 RuBP
4. carbohydrate synthesis = remaining 2 G3P used to form glucose

Question 17

is calvin cycle light dependent or independent

Answer 17

independent
requires high energy molecule NADPH and ATP produced in the light rxn

Question 18

action spectrum

Answer 18

chloroplasts are highly effective at absorbing red and blue light
green wavelengths are reflected making it least effective at photosynthesis

Question 19

photolysis

Answer 19

H2O splits into 2H+, 2e-, and 1/2 O2
2H+&raquo_space; NADPH formation
2 e- lost in PSII is replenished through this process
1/2 O2&raquo_space; released as gas

Question 20

where does photolysis occur

Answer 20

PSII

Question 21

chemiosmosis

Answer 21

uses H+ gradient to create ATP

Question 22

in chemiosmosis where does H+ accumulate

Answer 22

in the thylakoid membrane
1. H+ released into the lumen through photolysis
2. between PSII and PSI, cytochromes bring H+ into the lumen from the stroma&raquo_space; this creates pH and electrical gradient

Question 23

ATP synthase uses a gradient to…

Answer 23

turn ADP into ATP
this ATP is used in calvin cycle to create glucose

Question 24

where does chemiosmosis occur

Answer 24

thylakoid membrane

Question 25

alternatives to C3 photosynthesis (there are 2)

Answer 25

C4 photosynthesis
CAM photosynthesis

Question 26

C4 photosynthesis

Answer 26

• alters location of photosynthesis
• CO2 moved to bundle sheath cells to minimize photorespiration and H2O loss
• produces an intermediary 4-carbon compound and uses 1 extra ATP

Question 27

CAM photosynthesis

Answer 27

• alters timing of photosynthesis
• fixes CO2 at night instead of day to minimize photorespiration and H2O loss