photosynthesis

Question 1

what does oxidation mean

Answer 1

. it gains oxygen or loses hydrogen
.when a substance is oxidised it loses electrons

Question 2

what does reduced mean?

Answer 2

loses oxygen or gains hydrogen
. a substance is reduced when it gains elelctrons

Question 3

what is a metabolic pathway

Answer 3

. a series of small reactions controlled by enzymes like respiration or photosynthesis

Question 4

define phosphorylation

Answer 4

adding a phosphate to a molecule

Question 5

define photophosphorylation

Answer 5

adding a phosphate to Another molecule USING LIGHT

Question 6

define photolysis

Answer 6

splitting of a molecule using light

Question 7

what is photo ionisation

Answer 7

when light energy excites electrons giving them more energy to be released.
the release of electrons causes the atom or molecule to be a positively charged ion

Question 8

what is hydrolysis

Answer 8

splitting of molecules using water

Question 9

what is decarboxylation

Answer 9

.removal of carbon dioxide from a molecule

Question 10

what is dehydrogenation

Answer 10

the removal of hydrogen from a molecule

Question 11

define photosynthesis

Answer 11

photosynthesis is the process where energy from light is used to make glucose from H2O and CO2

Question 12

what coenzymes are involved in photosynthesis

Answer 12

.NADP

Question 13

what is the role of coenzymes

Answer 13

.a coenzyme is a molecule that aids the function of an enzyme by transferring a chemical group form one molecule to another

Question 14

what photosynthetic pigments are there in chlorophyll

Answer 14

chlorophyll b
chlorophyll a
carotene

Question 15

what is the point of these photosynthetic pigments?

Answer 15

.they absorb the wavelength of light needed for photosynthesis
. found in thylakoid membranes

Question 16

where does light dependent reaction take place?

Answer 16

thylakoid membranes of chloroplasts

Question 17

describe the first step of the process of LDR reaction?

Answer 17

1. chlorophyll absorbs light, light energy excites electrons and causes them to get released from chlorophyll to and move down an electron transfer chain to PSI ,leading to photo ionisation of chlorophyll

Question 18

describe the second step of the process of LDR reaction?

Answer 18

2.as the electrons leave, the chlorophyll is now in need of new electrons , the .photolysis of water provides electrons.
.light energy splits 2 H2O into 4H ions, 4 electrons and o 2 oxygens

Question 19

describe the third step of the process of LDR reaction?

Answer 19

some of the energy from electrons released during photo ionisation is conserved in the production of ATP and reduced NADP

Question 20

where does LIR reaction happen?

Answer 20

in the stroma

Question 21

what is the 1st step of LIR reaction

Answer 21

1. carbon dioxide diffuses through stomata and reacts with ribulose bisphosphate (RuBP) to form two molecules of glycerate 3-phosphate (GP).
   This reaction is catalysed by the enzyme rubisco

Question 22

what is the 2nd step of LIR reaction

Answer 22

2. ATP and reduced NADP from the light-dependent reaction are used to reduce GP to triose phosphate

Question 23

what is the 3rd step of LIR reaction

Answer 23

3. ATP turns GP to TP because of some of the triose phosphate is converted to useful organic substances.
   .organic substances have 6 carbon molecules, in order to make one hexose sugar we need the Calvin cycle to happen 6 times

Question 24

what is the 4th step of LIR reaction

Answer 24

some of the triose phosphate is used to regenerate RuBP in the Calvin cycle

Question 25

what are the 3 limiting factors fro photosynthesis

Answer 25

temperature light intensity CO2

Question 25

what is the optimum light intensity and why?

Answer 25

.high light intensity .light is needed to provide energy, the higher the light intensity the more energy it provides

Question 25

what is the optimum temperature and why?

Answer 25

.25 degrees .photosynthesis involves enzymes like ATP synthase and rubisco .if its low enzymes are inactive and if it is too high(45) they may denature

Question 25

what is the optimum co2 levels and why?

Answer 25

.0.4% .this is high and gives a higher rate of photosynthesis .however any higher will cause stomata to close

Question 26

how do growers optimise their temperature?

Answer 26

.glasshouses trap heat energy form sunlight .heaters and cooling systems control temperature

Question 27

how do growers optimise their co2 levels?

Answer 27

.burning fuels ( propane in co2 generator)

Question 27

how do growers optimise their light intensity?

Answer 27

.lamps at night and glass green houses in the morning

Question 28

what does chromatography provide?

Answer 28

it shows which pigments are present in the leaves

Question 29

describe chromatography steps

Answer 29

1.grind up leaves with anhydrous sodium sulfate and propanone 2.transfer to test tube with petroleum ether and shake to form two distinct layers, use top one 3.transfer top pigment layer to a test tube with anhydrous sodium sulfate 4.draw horizontal pencil line near bottom of TLC paper and build concentrated spot of pigment called origin 5.place paper in solvent below origin 6.stop before solvent reaches the top

Question 30

how is RF value calculated

Answer 30

distance travelled by spot / distance travelled by solvent

Question 31

how can you measure the rate of dehydrogenase activity

Answer 31

.by measuring the rate at which DCPIP loses its blue colour.

Question 32

what is the role of dehydrogenase enzyme?

Answer 32

in photosystem 1, during the light dependent reaction, NADP acts as an electron acceptor and is reduced. this is catalysed by the enzyme dehydrogenase

Question 33

describe the experiment

Answer 33

1. grind up leaves with chilled isolation solution 2. filter liquid into a beaker 3.transefer liquid into centrifuge at high speed 4. resuspend pellet of chloroplasts into the chilled isolation solution 5. set up colorimeter and zero it using cuvette containing chloroplasts and distilled water 6.add a set amount of DCPIP and chloroplasts in test tube, place each tube at a different distance away from light. 7. record absorbance in colorimeter every 2 minutes