Photosynthesis

Question 1

what type of activity is photosynthesis

Answer 1

biosynthetic

Question 2

what are two significant outcomes of PS

Answer 2

produces all organic material required by consumers, produces oxygen required by animals

Question 3

where is photosynthesis performed

Answer 3

chloroplasts in green tissue of leaves

Question 4

what are the parts of chloroplasts

Answer 4

thylakoid
granum = stacks of thylakoids
stroma = aqueous phase where many BC reactions takes place

Question 5

what is the energy source of PS

Answer 5

sun

Question 6

where is energy stored in glucose

Answer 6

chemical bonds within carbs

Question 7

what is photosynthesis the transfer of

Answer 7

light energy —> chemical energy

Question 8

what is oxidized/reduced in PS

Answer 8

water = oxidized
co2 = reduced

Question 9

where is water split

Answer 9

H2O: O –> O2, H —> C5H12O6 and H2O
CO2: C —> C6H12O6, O —> C6H12O6 and H2O

Question 10

what are the three steps of PS, where do they occur

Answer 10

1. photochemistry (light) = thylakoid
2. production of NADPH and ATP (light) = thylakoid
3. incorporation of Co2 —> carbohydrate (dark) = stroma

Question 11

what do pigments do in step 1

Answer 11

transfer radiant energy to chemical bonds

Question 12

what do enzymes do in steps 2 and 3

Answer 12

transfer chemical energy

Question 13

what is light

Answer 13

electromagnetic radiation characterized by its energy

Question 14

what are three things that can occur when light meets matter

Answer 14

reflected, transmitted, absorbed

Question 15

what are three classes of pigments

Answer 15

chlorophylls (chl a and b)
carotenoids
phycobilins (red algae and cyanobacteria, chl a and c, not b)

Question 16

what can pigments do

Answer 16

absorb certain wavelengths of visible light, reflect or transmit the rest

Question 17

why are leaves green

Answer 17

chloroplasts dont absorb green light, green light bounces back to eye

Question 18

what is the absorption spectrum

Answer 18

absorbance response of a pigment exposed to a series of wavelengths of light

Question 19

what is the action spectrum

Answer 19

physiological response of the organisms to specific wavelengths

Question 20

which wavelengths are most effective for driving photosynthesis?

Answer 20

red and blue

Question 21

which wavelength is least effective for driving photosynthesis

Answer 21

green

Question 22

what is the difference in structure of chl a and b

Answer 22

chl a = ch3, chl b = cho

Question 23

what is the function of the porphyrin ring in chlorophyll

Answer 23

light absorbing head with magnesium in the centre

Question 24

what is the function of the hydrocarbon tail of chlorophyll

Answer 24

interacts with hydrophobic regions of proteins inside thylakoid membranes of chloroplasts

Question 25

what is the function of conjugated double bonds in the porphyrin ring

Answer 25

allows electrons to flow in ring --> creates electron cloud around Mg

Question 26

what happens when light hits the double bond system

Answer 26

1 or 2 electrons go into an excited state by absorbing the energy and emit light as photon/heat

Question 27

what are light harvesting complexes

Answer 27

where chl a, b and carotenoids transfer energy, embedded in protein complex, link together pigments

Question 28

what are light harvesting complexes connected to

Answer 28

reaction centres

Question 29

what occurs in reaction centres

Answer 29

transfer of electrons to primary electron acceptor

Question 30

what makes up a photosystem

Answer 30

light harvesting complexes and reaction centre

Question 31

what is the first step in photosystem II

Answer 31

light excites pigment ---> excited e- ---. e- falls to ground state while another e- is excited ---> energy passed until e- in P680 is excited

Question 32

what is the second step that occurs in PSII

Answer 32

transfer of e- from chl a pair (P680) to primary electron acceptor P680 ---> P680+

Question 33

what is the third step in PSII

Answer 33

e- hole in P680+ must be filled (strongest oxidizing agent) ---> pulls e- from water

Question 34

what is the reaction between water and P680+

Answer 34

H2O + 2P680+ ---> 1/2O2 + 2H+ + 2e- + 2P680

Question 35

what happens after PSII

Answer 35

ETC transfers electron down through a cytochrome complex to PSI, synthesizing ATP

Question 36

what occurs at PSI

Answer 36

same as PSII, pigment gets excited, electron excited, energy passed through electrons until P700 is reached and transfers electron to primary acceptor

Question 37

how is the whole is P700 filled

Answer 37

by electron coming from PS II via the ETC

Question 38

what occurs after PS I

Answer 38

second ETC transports electron to NADP+ reductase, synthesizing NADPH

Question 39

In ATP production, where is the H+ gradient, what is this process called

Answer 39

high in thylakoid space, low in stroma, photophosphorylation

Question 40

what happens when the lights go out?

Answer 40

all light reactions stop, co2 absorption and sugar production continues as long as substrates are available

Question 41

what are the three steps of the calvin cycle

Answer 41

carbon fixation, reduction, regeneration

Question 42

what is the input/output of the calvin cycle

Answer 42

Input: 3 Co2 molecules 6 G3P molecules are made (5 stay one leaves) Output: 1 G3P, 9 ADP, 6 NADP+

Question 43

what occurs in carbon fixation

Answer 43

3 Co2 molecules enter one at a time and react with RuBP

Question 44

what occurs during reduction

Answer 44

6 ATP ---> 6 ADP 6 NADPH ---> 6 NADP+ & 6Pi Output: 1 G3P

Question 45

what occurs during regeneration

Answer 45

3 ATP ---> 3 ADP

Question 46

how many turns of the calvin cycle are needed to generate one glucose molecule

Answer 46

6

Question 47

what can G3P create

Answer 47

proteins, lipids, carbs, DNA/RNA, hormones, secondary metabolites