Chapter 16

Question 1

Equation for photosynthesis

Answer 1

6 CO2 + 6 H2O –> C6H12O6 + 6 O2

Question 2

Photosynthesis equation represents what two processes

Answer 2

light reactions
dark reactions

Question 3

Light reactions

Answer 3

NADPH and ATP are produced
requires light

Question 4

Dark reactions

Answer 4

ATP and NADPH provide the energy and reducing power for the fixation of CO2
do not require light energy- can occur in light or dark

Question 5

Where do the energy-transducing reactions occur

Answer 5

thylakoid membrane

Question 6

Common chloroplast photoreceptors

Answer 6

chlorophyll b- methyl group replaced by an aldehyde group
chlorophyll- main photoreceptor

Question 7

carotenoids

Answer 7

absorb in other portions of the visible spectrum and transfer energy to chlorphylls

Question 8

how do Photosynthetic units work

Answer 8

excited electrons are passed from one chlorophyl to the next until it reaches a reaction center

Question 9

Goal of light reactions

Answer 9

to generate ATP and NADPH using light energy

Question 10

Light reaction occur in _____ and involves ___

Answer 10

thylakoid membranes
two photosystems- Photosystem I and II

Question 11

Light reactions have a series of redox reactions coupled to phosphorylation of ADP to ATP in a process called

Answer 11

photophosphorylation

Question 12

Photosystem I does what

Answer 12

reduction of NADP+ to NADPH

Question 13

Photosystem II does what

Answer 13

the oxidation of H2O to O2

Question 14

Light reaction is

Answer 14

endergonic
driven by light energy absorbed by the chlorophylls of the two photosystems

Question 15

Photosystem II is a

Answer 15

H+ pump
four photooxidation events in photosystem II oxidize two H2O molecules and produce one O2 molecule

Question 16

light switches photosystem II’s pair of _____ into _____ and then into _____ upon donation of the e- to PQ

Answer 16

chlorophyll
strong reductant P680
the strongest oxidant P680+

Question 17

What does P680 oxidized

Answer 17

P680 strips 4 electrons out of water, oxidizing it to O2

Question 18

Components of the electron transport chain of the thylakoid membrane

Answer 18

Photosystem II
Cyt b6/f
photosystem I
ATP synthase

Question 19

Cytochrome b6f function

Answer 19

H+ pump driven by electron transport and very similar to complex III from mitochondria

Question 20

Plastocyanin

Answer 20

functions as a one-electron carrier by cycling between the Cu+ and Cu2+ oxidation states
mobile carrier of 1 e-, like cytochrome c in mitochondria

Question 21

in linear electron flow, ferredoxin serves as

Answer 21

a substrate for ferredoxin-NADP+ reductase

Question 22

The core of each photosystem I is a pair of chlorophyll molecules

Answer 22

P700

Question 23

Electron transport in the thylakoid membrane also creates a proton gradient by ____ methods

Answer 23

three

Question 24

Methods of making a proton gradient

Answer 24

1. proton pumping from the stroma into the thylakoid lumen by the Cyt b6/f complex using the energy of electron transport from photosystem II to Photosystem I
2. by splitting of H2O which releases H+ into the thylakoid space for lumen
3. when photosystem I reduces NADP+ by using H+ in the stroma to produce NADPH (lowers H+ concentration)

Question 25

The flow of H+ back to the stroma through ______ provides the energy synthesis of ATP from ADP and Pi

Answer 25

ATP synthase

Question 26

Steps of photophosphorylation

Answer 26

1. proton pumping coupled with the electron transport
2. splitting of H2O releases H+
3. removal of H+ to make NADPH

Question 27

Cyclic electron transport in PSI can be coupled to ____ when NADP+ is lacking

Answer 27

ATP production

Question 28

The calvin cycle takes place in the

Answer 28

stroma of chloroplast

Question 29

Carbon dark reactions are also known as

Answer 29

Calvin cycle

Question 32

goal of calvin cycle

Answer 32

fix CO2 by reacting it with ribulose-1,5-bisphosphate to produce two molecules of 3-phosphoglycerate which can make glucose

Question 33

Calvin cycle
Substrate-
Product-

Answer 33

substrate- CO2
Product-GAP
Glyceraldehyde-3-phosphate

Question 34

Most abundant protein on earth

Answer 34

Rubisco

Question 35

Increasing Rubisco activity using genetically engineered plants could

Answer 35

reduce CO2 abundance in the atmosphere and reduce the greenhouse effect

Question 36

First reaction of the Calvin cycle

Answer 36

carboxylation of six molecules of ribulose-1,5-bisphosphate
the actual carbon fixation step
each carboxylation product splits to give two molecules of 3-phosphoglycerate (12 total)

Question 37

Rubisco is not a

Answer 37

highly specific enzyme

Question 38

Photorespiration

Answer 38

fixing O2 rather than CO2 by Rubisco
unavoidable by-product of photosynthesis
is wasteful

Question 39

C4 pathway- carbon fixation in tropical plants

Answer 39

CO2 enters the outer cells and reacts with phosphoenolpyruvate to give oxaloacetate and Pi- reduced to malate
malate provides a way to move CO2 into the interior cells with lower oxygen thereby avoiding wasteful photorespiration by rubisco in the presence of oxygen

Question 40

Calvin cycle products are used to

Answer 40

synthesize sucrose

Question 41

Calvin cycle products are used to synthesize

Answer 41

starch