5.5 Photosynthesis - light dependant & independent

Question 1

(light dependant) 1. what does photosystem 2 (ps2) absorb and what effect does this have?

Answer 1

light

excites electrons

Question 2

(light dependant) 2. excited electrons pass to where?

Answer 2

electron transport chain

Question 3

(light dependant) 3. ATP is made in what process?

Answer 3

chemiosmosis

Question 4

(light dependant) 4. electrons pass down the chain to where?

Answer 4

photosystem 1 (ps1)

Question 5

(light dependant) 5. electrons lost from ps2 are replaced by what?

Answer 5

electrons from photolysis

Question 6

(light dependant) 6. the electrons from ps1 pass to where?

Answer 6

electron transport chain

Question 7

(light dependant) 7. in non cyclic photophosphorylation, where do the electrons that leave the ETC after ps1 go?

Answer 7

accepted by coenzyme NADP with a hydrogen ion

Question 8

(light dependant) what does reduced NADP do?

Answer 8

provides the H+ in the light independent reaction

Question 9

(light dependant) what occurs in cyclic photophosphorylation?

Answer 9

the electron is fed back into ps1

Question 10

(light dependant) what is photolysis?

Answer 10

water split into H+, e- and O2 using energy from the sun

Question 11

(light dependant) equation for photolysis:

H2O —>

Answer 11

2H+ + 2e- + 1/2 O2

Question 12

(light dependant) what is the enzyme forming part of the ps2 catalysing the breakdown of water?

Answer 12

the O2 evolving complex

Question 13

(light dependant) protons are released into the lumens of the thylakoids increasing what?

Answer 13

the proton concentration gradient across the membrane

Question 14

(light dependant) protons diffuse back down an electrochemical gradient driving what?

Answer 14

the formation of ATP

Question 15

(light dependant) what happens to the proton once it returns to the stroma?

Answer 15

combines with electron and NADP to form reduced NADP

Question 16

(light dependant) the process removes protons from the stroma helping maintain what?

Answer 16

the proton gradient across the thylakoid membrane

Question 17

can photosynthesis occur in the dark?

Answer 17

only the light independent stage

Question 18

when will the light independent stage stop in the dark?

Answer 18

when there is no reduced NADP and ATP left over from the light dependent reaction

Question 19

where does the light dependant stage take place?

Answer 19

within the grana

Question 20

where does the light independent stage take place?

Answer 20

in the matrix

Question 21

what pigments are embedded in the thylakoid membrane?

Answer 21

chlorophyll a
chlorophyll b
xanthophylls
carotenoids

Question 22

pigments and other proteins form a light harvesting system called what?

Answer 22

the antennae complex

Question 23

what is the role of the antennae complex?

Answer 23

to absorb/harvest light energy at different wavelengths & transfer energy to the reaction centre

Question 24

what is located in the reaction centre?

Answer 24

chlorophyll

Question 25

(pigment) what is a photosynthetic pigment?

Answer 25

coloured biological compound present in chloroplasts and photosynthetic bacteria which captures light energy for photosynthesis

Question 26

what pigment gives plants their green colour?

Answer 26

chlorophyll - it reflects green light

Question 27

what pigment gives plants a red - yellow colour?

Answer 27

carotenoids

Question 28

(light independent) what is the light independent stage also known as?

Answer 28

the calvin cycle

Question 29

(light independent) 1. CO2 diffuses into the leaf through what?

Answer 29

spongy mesophyll cells

Question 30

(light independent) 2. from the spongy mesophyll CO2 diffuses where?

Answer 30

into the stroma of chloroplasts

Question 31

(light independent) 3. what does CO2 combine with?

Answer 31

ribulose bisphosphate | this fixes the CO2

Question 32

(light independent) how many carbons does ribulose bisphosphate have?

Answer 32

5

Question 33

(light independent) 4. which enzyme catalyses CO2 combining with ribulose bisphosphate?

Answer 33

Rubisco

Question 34

(light independent) 5. CO2 + Ribulose forms an unstable six carbon molecule which breaks down to form what?

Answer 34

2 Glycerate 3 phosphates

Question 35

(light independent) 6. what are the glycerate 3 phosphates converted into?

Answer 35

2 triose phosphates

Question 36

(light independent) 7. how are the glycerate 3 phosphates converted to triose phosphates?

Answer 36

using hydrogens from reduced NADP and energy from ATP

Question 37

(light independent) 8. what is done with most of the TP?

Answer 37

recycled into RUBP

Question 38

(light independent) 9. what happens to the rest of the TP not used to make RUBP?

Answer 38

used to make lipids, glucose and amino acids

Question 39

(light independent) for one glucose to be made how many CO2 have to enter the calvin cycle?

Answer 39

6

Question 40

(light independent) 6 full turns of the calvin cycle produces how many triose phosphates?

Answer 40

12

Question 41

(light independent) of the 12 triose phosphates made in the calvin cylcle how many are removed to make glucose?

Answer 41

2

Question 42

(light independent) how many triose phosphates are recycled to regenerate 6 RuBP?

Answer 42

10