photosynthesis

Question 1

why is the upper epidermis transparent

Answer 1

allows more light to be absorbed by chloroplast

Question 2

why are palaside mesophyll cells verticle

Answer 2

to increase photosynthesis

Question 3

how are leave arrangements made to maximise photosynthesis

Answer 3

minimal overlapping so no shade

Question 4

how do stoma maximise photosynthesis

Answer 4

open and close in responce to changes in light intensity

Question 5

why do leaves have a large surface area

Answer 5

collects as much solar energy as possible

Question 6

why are their aire spaces in the lower mesophyll

Answer 6

to allow diffusion and storage of co2 and o2

Question 7

structure of the chloroplast

Answer 7

outer membrane
stroma
thylakoid
thylakoid membrane
inner membrane

Question 8

describe the light dependant reaction

Answer 8

occures between the stroma and the inner thylakoid
photosystem captures solar energy
accessory pigments vibrate when light hits them
it forces energy down to chlorophyll A in the reaction centre
when enough energy is absorbed 2 electrons explode of magnesium
magnesium gets more electrons by photolysis in the reaction centre

Question 9

what is photolysis

Answer 9

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

Question 10

where does the oxygen go after photolysis

Answer 10

diffuses to atmosphere or mitchrocondria for respiration

Question 11

what is the reaction centre

Answer 11

at the bottom of the photosystem
with primary pigment chlorophyll A
Mg+ and hydrophobic tail

Question 12

where does the light independant reaction occur

Answer 12

in the stroma

Question 13

describe how ATP is produced

Answer 13

electrons bounce from one cytochrome to another loosing strength, this is called the electron transport chain
electrons move into the reaction centre of PS1
the electrons helpt to pump protons into the thylakoid by active transport
H+ ions move by facilitated diffusion through ATP synthase down the electrochemical gradient
chemiosmosis occurs to produce ATP
excited electrons are released and react with H+ ions to reduce NADP

Question 14

what is proton motive force

Answer 14

desire of protons to leave the thylakoid because of the force of their possitive charge

Question 15

describe the light independant reaction

Answer 15

CO2 is added to the reaction and binds to RuBP which has 5 carbons by the enzyme rubisco
this produces 2 molecules of 3 carbon GP
reduced NADP becomes NADP and the H+ is used to make TP. this is catalysed by the bendohydrogenase enzyme
ATP is broken down
some of the TP leaves as glucose

Question 16

what does RuBP mean

Answer 16

ribulose bisphosphate

Question 17

what does GP mean

Answer 17

glycerate phosphate

Question 18

what does TP mean

Answer 18

triose phosphate

Question 19

what is the limiting factor

Answer 19

factor limiting the rate of photosynthisis

Question 20

what is the compensation point

Answer 20

when there is no net exchange of gases in or out of the plant

Question 21

why is light intensity a limiting reactant

Answer 21

because it is too low for the light dependant reaction
this means the level of ATP and Red NADP will also be low so the light independant reaction will also be running slowly

Question 22

why is carbon dioxide a limiting factor

Answer 22

because at high light intensity the light dependant reaction is running very fast so lots of ATP and reduced NADP are made
but if their isnt enough CO2 it limits rate of reaction

Question 23

why is temperature a limiting factor

Answer 23

because the enzyme ribsico in the light independant reaction wont be running fast enough if temperature is low, decreasing rate of photosynthesis

Question 24

why might water be considered a limiting fator

Answer 24

because low water levels causes stomata to close
but then CO2 cant get in
so CO2 becomes the limiting factor

Question 25

what happens to the clavin cyle in low light intensity

Answer 25

GP conc increases because less ATP and RED NADP is available to convert it to TP
TP conc decreases
RUBP conc decreases

Question 26

what happens in the calvin cycle in low CO2 conc

Answer 26

GP conc decreases because less RUBP combines with CO2
less TP conc
RUBP conc increaes because less of it reacts with CO2