Photosynthesis

Question 1

What are the two main stages of photosynthesis

Answer 1

Light-dependent reactions and carbon reactions (Calvin Cycle)

Question 2

Where do light-dependent reactions occur

Answer 2

Thylakoid membranes

Question 3

What are the products of the light-dependent reactions

Answer 3

ATP and NADPH

Question 4

What is the role of ATP and NADPH

Answer 4

To fuel the Calvin Cycle

Question 5

Where does PSII localise

Answer 5

Appressed regions of thylakoid membrane

Question 6

Where does PSI and ATP synthase localise

Answer 6

Non-appressed regions of thylakoid membrane

Question 7

What is the structure of LHCII

Answer 7

Tetramer

Question 8

What pigments are in LHCII

Answer 8

Chlorophyll and carotenoids

Question 9

What does LHCII associate with

Answer 9

PSI or PSII

Question 10

What does LHCII kinase do

Answer 10

Causes LHCII to dissociate from PSII and bind PSI

Question 11

What does LHCII phosphatase do

Answer 11

Causes LHCII to dissociate from PSI and bind PSII

Question 12

What triggers LHCII kinase

Answer 12

Build-up of reduced plastoquinol (QH2)

Question 13

How does ATP synthase generate ATP

Answer 13

Protons diffuse and rotate c-subunits

Question 14

Where is ATP produced

Answer 14

Stroma

Question 15

Where is NADPH produced

Answer 15

Stroma

Question 16

Where are protons produced

Answer 16

Thylakoid lumen

Question 17

What is the purpose of ATP and NADPH

Answer 17

To drive the Calvin Cycle

Question 18

What are alternate names for the Calvin Cycle

Answer 18

Calvin-Benson cycle

Question 19

What are the three stages of the Calvin Cycle

Answer 19

Carboxylation

Question 20

What enzyme catalyses CO2 fixation

Answer 20

RuBISCO

Question 21

What is the product of RuBP + CO2

Answer 21

Two molecules of 3-phosphoglycerate (3PGA)

Question 22

Where is RuBISCO large subunit synthesised

Answer 22

Chloroplast

Question 23

Where is RuBISCO small subunit synthesised

Answer 23

Cytoplasm (imported into chloroplast)

Question 24

What imports the small subunit of RuBISCO

Answer 24

TOC and TIC translocons

Question 25

What regulates RuBISCO

Answer 25

Light via thioredoxin and RuBISCO activase

Question 26

What are the products of the reduction phase

Answer 26

G3P and DHAP (triose phosphates)

Question 27

What enzyme interconverts DHAP and G3P

Answer 27

Triose phosphate isomerase

Question 28

What happens when plant needs carbs

Answer 28

Sucrose is synthesised in cytoplasm

Question 29

What happens when plant has enough carbs

Answer 29

Starch is synthesised in chloroplast

Question 30

What enables triose phosphate export

Answer 30

Pi import

Question 31

What happens when Pi is low

Answer 31

Triose phosphate stays in chloroplast for starch synthesis

Question 32

How many triose phosphates are used to make carbs

Answer 32

One

Question 33

What are the other five triose phosphates used for

Answer 33

Regeneration of RuBP

Question 34

What regulates regeneration enzymes

Answer 34

Light (via thioredoxin and pH)

Question 35

Which enzymes are light-regulated

Answer 35

RuBISCO

Question 36

What are the two functions of RuBISCO

Answer 36

Carboxylation and Oxygenation (photorespiration)

Question 37

What does RuBISCO produce when using O2

Answer 37

Phosphoglycolate and 3-phosphoglycerate

Question 38

Why is phosphoglycolate problematic

Answer 38

It is useless and must be recycled via glyoxylate cycle

Question 39

What are the three photosynthetic pathways

Answer 39

C3

Question 40

Where is RuBISCO active in C3 plants

Answer 40

Mesophyll cells

Question 41

Where is RuBISCO active in C4 plants

Answer 41

Bundle sheath cells

Question 42

What fixes CO2 in C4 mesophyll cells

Answer 42

PEP carboxylase

Question 43

What is the 4-carbon compound formed in C4 plants

Answer 43

Malate

Question 44

Where is malate transported in C4 plants

Answer 44

Bundle sheath chloroplasts

Question 45

What happens to malate in bundle sheath cells

Answer 45

CO2 is released for RuBISCO

Question 46

What is the waste product of malate decarboxylation

Answer 46

Pyruvate

Question 47

Where does pyruvate go

Answer 47

Back to mesophyll to regenerate PEP

Question 48

What is the main aim of CAM photosynthesis

Answer 48

Reduce water loss by closing stomata during day

Question 49

When do CAM plants fix CO2

Answer 49

At night

Question 50

What enzyme fixes CO2 in CAM plants

Answer 50

PEP carboxylase

Question 51

What is CO2 stored as in CAM plants

Answer 51

Oxaloacetate/malic acid

Question 52

When is CO2 released in CAM plants

Answer 52

During the day