Mod 8 Photosynthesis

Question 1

What best describes the “Z scheme” in photosynthesis?

Answer 1

Electron flow between PSII and PSI, which results in formation of ATP and NADPH

Question 2

What is function of ATP synthase in thylakoid membrane?

Answer 2

Generate ATP from ADP and inorganic phosphate

Question 3

In Calvin cycle - what enzyme catalyzes first step, carboxylation of RuBP?

Answer 3

RuBisCO

Question 4

What stages are part of photosynthesis reactions

Answer 4

Light captured, Carbon fixation

Question 5

Oxidation of water results in production of :

Answer 5

electrons, protons, O2

Question 6

What are the electron donors in photosynthesis reactions?

Answer 6

H2O

Question 7

Where do eukaryotic cells in photosynthesis take place in?

Answer 7

chloroplast

Question 8

What are the characteristics of chloroplasts?

Answer 8

self-replicate and semi-autonomous

Question 9

what is the highly folded flattened membrane sac?

Answer 9

thylakoids

Question 10

what is the fluid-filled space inside the thylakoid membrane?

Answer 10

lumen

Question 11

what is the orderly stacks of thylakoids?

Answer 11

grana

Question 12

what is the space surrounding thylakoids?

Answer 12

stroma

Question 13

in light-dependent reactions, what is the products?

Answer 13

ATP and NADPH

Question 14

how is light absorbed?

Answer 14

energy from sun form electromagnetic radiation - travels in photons

Question 15

what happens when photons become absorbed

Answer 15

converted into higher state - considered excited state

Question 16

what are the three ways to re-establish ground state?

Answer 16

dissipate energy as heat, re-emit energy in a longer wavelength (fluorescence), transfer energy to another molecule (happens with photosynthetic pigments)

Question 17

why is leaf green?

Answer 17

because contains pigment chlorophyll (poor at absorbing green), and instead absorbs red and blue

Question 18

what are the two components of chlorophyll?

Answer 18

porphyrin ring, and phytol side chain

Question 19

what is the porphyrin ring?

Answer 19

absorbs light, specific atom in center of ring - Mg, different side groups of ring - gives different types of chlorophyll

Question 20

what is the phytol side chain?

Answer 20

insert chlorophyll in lipid bilayer, thylakoid membrane

Question 21

Where are accessory pigments found?

Answer 21

in thylakoid membrane - e.g. carotenoids

Question 22

What are the characteristics of accessory pigments?

Answer 22

absorb light from regions of visible spectrum , poorly absorbed by chlorophyll
- increase efficiently of light absorption
- protects photosynthetic components from damage

Question 23

what happens when chlorophyll absorbs light?

Answer 23

one of its electrons are elevated to a higher-energy state

Question 24

what happens when chlorophylls are beside another chlorophyll molecule, and is called the reaction center?

Answer 24

energy can be transferred by antenna to pass energy to another electron, by bumping of one electron to another

Question 25

Before reaction center can take on more light energy - must acruie electron from electron donor, and where does this electron come from?

Answer 25

H2O

Question 26

how to photosynthesis begin absorption of light?

Answer 26

by protein-pigment complexes - photosystems

Question 27

which photosystem occurs first?

Answer 27

photosystem II, PSII

Question 28

how are the two photosystems connected?

Answer 28

by photosynthetic electron transport chain

Question 29

what drives the formation of NADPH and ATP

Answer 29

electron transport chain

Question 30

what is the energy level throughout the electron transport chain?

Answer 30

move from initial high energy level, but drops as it goes through electron transport chain

Question 31

what does the light energy from PSI do?

Answer 31

raises electron energy to be high enough to be used to reduce NADP+

Question 32

what is the flow of electrons in photosystem?

Answer 32

between H2O and PSII, and between PSII and PSI (electron transport chain), and between PSI and NADP+

Question 33

what happens when electrons flow along Z pathway?

Answer 33

H+ ions move from stroma to inner compartment of thylakoids

Question 34

What is the proton concentration?

Answer 34

higher in lumen of thylakoid, and lower in stroma

Question 35

what happens to the ATP produced in the chloroplast?

Answer 35

remains in chloroplast due to carbon fixation reactions

Question 36

how is ATP produced in chloroplast?

Answer 36

ATP is produced by enzymes in ATP synthase, resulting from moving electrons from PSII through PSI

Question 37

what are the electron carriers that pass through PSII and PSI through cytochrome b6f complex?

Answer 37

plastoquinone and plastocyanin

Question 38

what does the plastoquinone do?

Answer 38

carries electrons from PSII to cytochrome b6f complex

Question 39

what does plastocyanin do?

Answer 39

carries electron from cytochrome b6f complex to PSI by diffusing through thylakoid lumen

Question 40

what are the reactions in calvin cycle?

Answer 40

carboxylation, reduction, regeneration

Question 41

what is required during the calvin cycle>

Answer 41

NADPH and ATP - 15 chemical reactions to synthesize carbohydrates from CO2

Question 42

what occurs during carboxylation?

Answer 42

CO2 from air combined with RuBP and forms 6-carbon molecules (that is catalyzed by rubisco) the 6 carbon molecule brown down into 3-carbon molecules of PGA

Question 43

what occurs during reduction?

Answer 43

potential energy of pGA is increased(so it must be reduced) reduction occurs by: PGA phosphorylated by ATP - produce triose phosphates AND triose phosphate molecules reduced by NADPH - exported out of chloroplast

Question 44

what occurs during regneration?

Answer 44

required energy in form of ATP produce three 5-C RuBP molecules to be later used in carboxyltoin portion of calvin cycle

Question 45

What happens if there is excess carbohydrates produced in calvin cycle?

Answer 45

converted into storage, formulation of starch granules

Question 46

What is the evolution of photosynthesis?

Answer 46

when bacteria only had single photosystem - cannot capture enoguh energy with one photosystem therefore: 1. horizontal gene transfer 2. gene duplication and divergence of one of the genes

Question 47

what are photosynthetic eukaryotes?

Answer 47

first organisms to use water, as electron donor - cyanobacteria cyanobacterium engulfed by eukaryotic cell overtime, cyanobacterium lost ability to live outside the host - became organelle we know as chloroplast