ch 4- photosynthesis

Question 1

photosynthesis

Answer 1

is the process of carbon fixation:

electrons from photolysis (splitting and excitement of water from solar energy) power carbon fixation

-atmospheric carbon dioxide is reduced
-releases o2
-creates chemical energy that can be transferred through food chains

-photons used to synth sugars in photosynth

Question 2

what energy producing and using recations are reverse of each other

Answer 2

photosynth and cellular respiration

photosynth- non spontaneous and endergonic

cellular respiration- spontaneous and exergonic

Question 3

mesophyl cells

Answer 3

between upper and lower epidermis of leaves

-facilitate gas movement within the leaf and contain CHLOROPLASTS

Question 4

where are chloroplasts found

Answer 4

plants
photosynth algae
NOT IN CYANOBACTERIA

Question 5

membrane of chloroplasts

Answer 5

outer and inner

both made of phospholipid bilayer and contain intermembrane space

Question 6

stroma

Answer 6

fluid materia that fills area inside inner membrane

location of calvin cycle

Question 7

thylakoids

Answer 7

membrane structure within STROMA

muliple stacks form a granum

site of light dependent reactions

-the lumen is high in H+ ions

Question 8

C3 vs C4 photosynth

Answer 8

C3- normal photosynth- three carbon PGA is formed

C4- four carbon intermediate is formed

uses spacial isolation of co2 to prevent photorespiration of plants in hot enviroment

Question 9

C4 photosynth steps

Answer 9

-CO2 fixed and forms 4 cabon oxaloacetate - converted to malate in mesophyll cells

-malate transferred to bundle sheath cells (low in O2)

-malate decarboxylated and fixed by RuBisCo to enter calvin cycle

Question 10

bundle sheath cells

Answer 10

leaf cells that form tightly packed layer surrounding the veins

Question 11

what does CAM stand for

Answer 11

crassulacean acid metabolism

Question 12

how does CAM photosynth work

Answer 12

uses temporal isolation to prevent photorespiration in hot and DRY enviroments

-stomata closed during day- prevent transpiration

-stomata open at night letting CO2 in to be fixed and form oxaloacetate and malate

-next day, stomata close, malate is decarboxylated temporally isolating CO2 from O2

-cO2 fixed by RuBisCo to enter the calvin cycle

Question 13

where do light dependent reactions occur

Answer 13

in the thylakoid membrane

Question 14

ATP generated in the light dependent reactions

Answer 14

is not used to power the cell, it is consumed in the calvin cycle

Question 15

phoyosystems

Answer 15

contain special pigments like chlorophyll that absorb photons

PII- 680 and PI- 700 are used in photosynth

Question 16

chlorophyl

Answer 16

pigment in photosystems

absorbs red and blue light and reflects green light

has a porphyrin ring with Mg bound to centre

Question 17

reaction centre

Answer 17

pair of chlorophyl molecules in the centre of photosystems

Question 18

what are the steps of non cyclic photophosphorylation

Answer 18

1. water is split- photolysis- protons move into thylakoid lumen
2. photons excite electons in rxn centre of PII- electrons go to primary acceptor
3. electron goes to ETC leading to protons pumping to thylakoid lumen from stroma- then electron goes to PI to excite its pigment
4. energized pigments energize electrons in reaction centre- e passed to another primary acceptor
5. e passed to short ETC ending in NADP+ reductase
6. protons travel down thier electochemical gradient from thylakoid lumen to generate ATP

Question 19

cyclic photophosphorylation

Answer 19

photosystem I returns it electrons to the first ETC instead of NADP+ reducatse causing more proton pumping and more ATP production and no NADP+ production

Question 20

calvin cycle

Answer 20

made of light indepenedent reactions- but depends on ATP and NADPH from the light dependent reactions

fixes CO2 in chloroplasts

Question 21

what are the steps of the calvin cycle

Answer 21

carbon fixation

reduction

regeneration

carbohydrate synth

Question 22

carbon fixation in calvin cycle

Answer 22

carbon dioxide combines with 5C RuBP

6 carbon molecule breaks into two PGA

reaction catalyzed by RuBisCo

Question 23

reduction step in calvin cycle

Answer 23

PGA phosphorylated by ATP and reduced by NADPH forming G3P

Question 24

regeneration and carb synth steps of calvin cycle

Answer 24

most of G3P is converted back to RuBP

while some is used to make glucose

Question 25

RuBisCo

Answer 25

fixes CO2 to RuBP and can also

bind Oxygen to RuBP- photorespiration -

Question 26

photorespiration

Answer 26

photorespiration - produces two phosphoglycolate that are converted to PGA
net loss of fixed carbon, no new glucose formed

C2 photosynth

Question 27

what is c2 photosynth

Answer 27

photorespiration