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A2 biology content > photosynthesis > Flashcards

photosynthesis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what does oxidation mean

A

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

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2
Q

what does reduced mean?

A

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

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3
Q

what is a metabolic pathway

A

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

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4
Q

define phosphorylation

A

adding a phosphate to a molecule

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5
Q

define photophosphorylation

A

adding a phosphate to Another molecule USING LIGHT

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6
Q

define photolysis

A

splitting of a molecule using light

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7
Q

what is photo ionisation

A

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

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8
Q

what is hydrolysis

A

splitting of molecules using water

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9
Q

what is decarboxylation

A

.removal of carbon dioxide from a molecule

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10
Q

what is dehydrogenation

A

the removal of hydrogen from a molecule

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11
Q

define photosynthesis

A

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

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12
Q

what coenzymes are involved in photosynthesis

A

.NADP

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13
Q

what is the role of coenzymes

A

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

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14
Q

what photosynthetic pigments are there in chlorophyll

A

chlorophyll b
chlorophyll a
carotene

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15
Q

what is the point of these photosynthetic pigments?

A

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

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16
Q

where does light dependent reaction take place?

A

thylakoid membranes of chloroplasts

17
Q

describe the first step of the process of LDR reaction?

A
  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
18
Q

describe the second step of the process of LDR reaction?

A

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

19
Q

describe the third step of the process of LDR reaction?

A

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

20
Q

where does LIR reaction happen?

A

in the stroma

21
Q

what is the 1st step of LIR reaction

A
  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
22
Q

what is the 2nd step of LIR reaction

A
  1. ATP and reduced NADP from the light-dependent reaction are used to reduce GP to triose phosphate
23
Q

what is the 3rd step of LIR reaction

A
  1. 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
24
Q

what is the 4th step of LIR reaction

A

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

25
Q

what are the 3 limiting factors fro photosynthesis

A

temperature
light intensity
CO2

25
Q

what is the optimum light intensity and why?

A

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

25
Q

what is the optimum temperature and why?

A

.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

25
Q

what is the optimum co2 levels and why?

A

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

26
Q

how do growers optimise their temperature?

A

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

27
Q

how do growers optimise their co2 levels?

A

.burning fuels ( propane in co2 generator)

27
Q

how do growers optimise their light intensity?

A

.lamps at night and glass green houses in the morning

28
Q

what does chromatography provide?

A

it shows which pigments are present in the leaves

29
Q

describe chromatography steps

A

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

30
Q

how is RF value calculated

A

distance travelled by spot / distance travelled by solvent

31
Q

how can you measure the rate of dehydrogenase activity

A

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

32
Q

what is the role of dehydrogenase enzyme?

A

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

33
Q

describe the experiment

A
  1. grind up leaves with chilled isolation solution
  2. filter liquid into a beaker
    3.transefer liquid into centrifuge at high speed
  3. resuspend pellet of chloroplasts into the chilled isolation solution
  4. 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.
  5. record absorbance in colorimeter every 2 minutes

A2 biology content (2 decks)

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