photosynthesis

Question 1

what are the two stages of photosynthesis

Answer 1

light dependent reaction
light independent reaction

Question 2

what key products are produced in the LDR

Answer 2

ADP
NADPH

Question 3

where does the light dependent reaction take place

Answer 3

thylakoids

Question 4

where does the light independent reaction take place

Answer 4

stroma

Question 5

what are the two groups of pigments

Answer 5

carotenoids
chlorophylls

Question 6

what are the main primary pigments

Answer 6

chlorophylls

Question 7

what are the main accessory pigments

Answer 7

carotenoids

Question 8

what is the absorption peak of PSII

Answer 8

P680nm

Question 9

what is the absorption peak of PSI

Answer 9

P700nm

Question 10

RF value =

Answer 10

distance by pigment divided by distance by solvent

Question 11

what are the 2 ways that ATP can be synthesised

Answer 11

1 non cyclic photophosphorylation
2 cyclic photophosphorylation

Question 12

what is the flow of electrons called

Answer 12

Z scheme

Question 13

stages of photophosphorylation in the LDR

Answer 13

1 photosystem 2 absorbs light
2 electrons raised to a higher energy level and leave chlorophyll molecule
3 electrons accepted by electron carrier
4 splitting of water/photolysis replaces electron
5 replacement e- accepted by chlorophyll molecule
6 electrons passed along electron carriers via redox reactions
7 causes pumping of protons into the thylakoid lumen
8 protons used to produce ATP by chemiosmosis
9 electrons enter PS1 and raised to a higher energy level
10 enter final electron carrier
11 electrons and protons reduce NADP which passes to calvin cycle with ATP

Question 14

what is the chemiosmostic theory

Answer 14

production of ATP involves electron transfer and the passage of protons across chloroplast membranes

Question 15

stages of chemiosmosis

Answer 15

1 electron flow provides energy to pump protons from stroma into thylakoid lumen.
2 creates a high conc of protons in thylakoid lumen and low in stroma
3 thylakoid membrane can maintain electrochemical gradient as it is impermeable to protons
4 protons move back into stroma via ATP synthase channel proteins
5 flow of protons leads to ATP formation (from ADP and Pi)

Question 16

stages of the Calvin cycle

Answer 16

1 fixation- RuBp reacts with CO2 catalysed by RUBISCO
2 produces 2 molecules of GP
3 some GP removed to form hexose sugars
4 GP reduced to form TP using ATP and NADPH from LDR
5 regeneration- RuBp regenerated using ATP

Question 17

effect of decreased light intensity

Answer 17

TP - less
GP - more
RuBp - less

Question 18

effect of increased CO2

Answer 18

TP - more
GP - more
RuBp - less

Question 19

effect of increased temperature

Answer 19

TP - more (until RUBISCO denatures)
GP - more (until RUBISCO denatures)
RuBp - less

Question 20

how is nitrogen absorbed

Answer 20

through roots as nitrates

Question 21

how is nitrogen transported

Answer 21

as nitrate in xylem
amino acids in phloem

Question 22

what is the appearance of a plant with nitrogen deficiency

Answer 22

chlorosis (yellowing of leaves)

Question 23

what is the role of magnesium

Answer 23

forms part of the chlorophyll molecule

Question 24

what is the appearance of a plant with magnesium deficiency

Answer 24

chlorosis (yellowing of leaves)

Question 25

what is the law of limiting factors

Answer 25

when a process depends on two or more factors, the rate of that process is limited by the factor which is in shortest supply.

Question 26

what factors will limit the rate of photosynthesis

Answer 26

CO2 concentration, light intensity, water, availability of chlorophyll

Question 27

what is the compensation point

Answer 27

where the rate of photosynthesis = the rate of respiration