chapter 22

Question 1

autotroph

Answer 1

photosynthetic organism

Question 2

heterotroph

Answer 2

organism that obtains energy from chemical fuels

Question 3

what are the light reactions

Answer 3

reactions powered by sunlight that produces high energy electrons and creates a proton - motive force similar to the ETC

Question 4

relate photosynthesis and cellular respiration

Answer 4

photosynthesis is the exact inverse of cellular respiration and they are ONLY the same in terms of end products and nothing else!!!!!

Question 5

features of the chloroplast

Answer 5

-double membrane organelle
-inner membrane surrounds a space called the stroma: site of dark reaction
-thylakoid membranes: location of light reactions

Question 6

how does photosynthesis begin

Answer 6

absorption of light by photoreceptor molecule = pigment!!

Question 7

what is the main photoreceptor in the chloroplast of green plants

Answer 7

chlorophyll a

Question 8

what happens when a photon is absorbed by a pigment?

Answer 8

an electron in the pigment molecule jumps to a higher energy state

Question 9

what are the two fates of the “excited” higher energy electron

Answer 9

1. fall to its original state, releasing the energy as light
2. move to a nearby molecule that has a lower excited state, a process called electron transfer

Question 10

what is the result of electron transfer

Answer 10

photoinduced charge separation because the initial molecule is now positively charged and the molecule that accepted the electron is negatively charged

Question 11

where does separation of charge happen

Answer 11

the reaction center

Question 12

what are the two photosystems

Answer 12

photosystem 1 and photosystem II

Question 13

what does photosystem I do

Answer 13

generates biosynthetic reducing power in the form of NADPH

Question 14

what does photosystem II do

Answer 14

replenishes the electrons of photosystem I while generating a proton gradient that is used to synthesize ATP

Question 15

the missing electrons in photosystem II are replaced by…

Answer 15

the photolysis of water

Question 16

what is the first accepter of electrons?

Answer 16

photosystem I

Question 17

photosystem I uses light energy to generate what powerful reductant

Answer 17

reduced ferredoxin

Question 18

the reaction center in photosystem I is called

Answer 18

p700

Question 19

the electrons from excited P700 go where

Answer 19

flow down an electron-transport chain to the iron-sulfur protein ferredoxin

Question 20

what does ferredoxin-NADP+ reductase do

Answer 20

transfers electrons from ferredoxin to form NADPH, biosynthetic reducing power

Question 21

the formation of NADPH occurs

Answer 21

on the stromal side of the thylakoid membrane, where it is used for carbohydrate synthesis

Question 22

the reaction center in photosystem II is called

Answer 22

P680

Question 23

excited P680 does what

Answer 23

transfers electrons from water to photosystem I in an ETC that includes pheophytin, a chlorophyll with protons replacing magnesium, plastoquinone, and cytochrome bf complex

Question 24

what does the ETC of pP680 contain

Answer 24

pheophytin, a chlorophyll with protons replacing magnesium, plastoquinone, and cytochrome bf complex

Question 25

how is a proton gradient generated by P680

Answer 25

electrons are transferred from water to plastoquinone

Question 26

P680 is bound to....

Answer 26

D1 and D2 subunits of the photosystem

Question 27

how do electrons flow upon excitation of P680

Answer 27

electrons flow from pheophytin, then to plastoquinone, and finally to reduce a mobile plastoquinone (QH2)

Question 28

what does P680+ do

Answer 28

extracts electrons from water bound at the manganese center to maintain redox balance

Question 29

what does cytochrome bf do

Answer 29

transfers electrons from plastoquinol (QH2) to plastocyanin (Pc)

Question 30

how is the proton-motive force generated

Answer 30

protons from plastoquinol are released into the thylakoid lumen, and cytochrome bf pumps 2 more protons from the stroma into the lumer

Question 31

the proton-motive force generation in plants is similar to what in cellular respiration

Answer 31

the mechanism of the Q cycle of Complex III

Question 32

where does photolysis of water occur

Answer 32

at the water-oxidizing complex (manganese center) of photosystem II

Question 33

how many photons are required to generate one water molecule

Answer 33

four photons

Question 34

the four electrons extracted from water are used to reduce

Answer 34

two Q to two QH2

Question 35

what is the source of O2 for all life

Answer 35

the photolysis of water

Question 36

what is the ATP synthase of the chloroplast called

Answer 36

CF1-CF0

Question 37

newly synthesized ATP is released where

Answer 37

into the stroma

Question 38

how does the membrane orientation of CF1-CF0 compare to the mitochondrial ATP synthase

Answer 38

it is reversed

Question 39

what happens to the cycle is the NADPH needs are met

Answer 39

ATP is generated without forming NADPH the electrons flow from ferredoxin through cytochrome bf to plastocyanin and then return to P700