5.1 Photosynthesis and respiration Flashcards

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1
Q

what is the equation for photosynthesis?

A

6CO2 + 6H2O = C6H12O6 + 6O2

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2
Q

name the two stages of photosynthesis

A
  1. light dependent reaction
  2. light independent reaction
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3
Q

where does the light dependent stage of photosynthesis take place?

A

the thylakoid membrane

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4
Q

where does the light independent stage of photosynthesis take place?

A

the stroma

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5
Q

what are the products of light dependent reactions?

A

ATP, NADPH (reduced NADP), O2

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6
Q

name the two uses of light energy in the light dependent stage of photosynthesis

A
  1. photophosphorylation: adding an inorganic phosphate ion to ADP to make ATP
  2. photolysis: splitting water into H+ ions and OH- ions
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7
Q

define photophosphorylation

A

using light energy to add phosphate to a molecule

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8
Q

define photolysis

A

using light energy to split a molecule

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9
Q

define photoionisation

A

using light energy to to ionise an atom or molecule

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10
Q

define electrochemical gradient

A

a concentration gradient of ions

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11
Q

define oxidation

A

gain of oxygen, loss of electron or hydrogen

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12
Q

define reduction

A

gain of electrons or hydrogen, loss of oxygen

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13
Q

define chemiosmosis

A

the process of electrons flowing down the electron transport chain and creating an electrochemical gradient which drives ATP synthesis

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14
Q

what products are released through non-cyclic photophosphorylation?

A

ATP, NADPH and oxygen

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15
Q

what products are released through cyclic photophosphorylation?

A

ATP

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16
Q

which photosystem is used first in non-cyclic photophosphorylation?

A

photosystem 2

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17
Q

what wavelength of light does photosystem 2 absorb?

A

P680

18
Q

what wavelength of light does photosystem 1 absorb?

A

P700

19
Q

describe the process of cyclic photophosphorylation

A

excited electrons in photosystem 1 are released to electron carriers, which pass them straight back to photosystem 1, meaning the only product is ATP

20
Q

describe 4 differences between cyclic and non-cyclic photophosphorylation

A
  1. photosystems 1 and 2 are used in non-cyclic, whilst only PS1 is used in cyclic
  2. photolysis of water is only required in non-cyclic, not cyclic
  3. NADPH is only synthesised in non-cyclic, not cyclic
  4. non-cyclic produces ATP, NADPH and oxygen, whereas cyclic only produces ATP
21
Q

describe the process of light dependent reactions in photosynthesis [5]

A
  1. light absorbed by chlorophyll excites electrons
  2. electrons move out of chlorophyll molecule and along electron transfer chain, releasing energy
  3. light energy is used for photophosphorylation to join ADP and Pi to form ATP
  4. photolysis of water produces protons, electrons and oxygen
  5. NADP is reduced when electrons and hydrogen join, becoming NADPH
22
Q

describe what happens during photoionisation in the light dependent reaction [2]

A
  1. chlorophyll absorbs light and excites electrons
  2. excited electrons are lost and chlorophyll become positively charged
23
Q

suggest and explain the advantage of having different coloured pigments in leaves [1]

A

absorbs different wavelengths of light for photosynthesis

24
Q

suggest two reasons why most of the light that falls on producers is not used in photosynthesis

A
  1. light is reflected
  2. light is wrong wavelength
25
Q

name the two products of the light-dependent reaction that are required for the light-independent reaction

A
  1. ATP
  2. reduced NADP (NADPH)
26
Q

explain how a reduced transfer of electrons down the chain reduces the rate of photosynthesis [4]

A
  • reduced transfer of electrons leads to a reduced transfer of of protons across the thylakoid membrane
  • so less ATP is produced
  • and less NADPH is produced
  • so light-independent reaction slows
27
Q

what wavelength of light does photosystem II absorb?

A

680nm

28
Q

what wavelength of light does photosystem I absorb?

A

700nm

29
Q

name five differences between the processes of cyclic and non-cyclic photophosphorylation

A
  1. in cyclic, only PSI is involved, whereas in non-cyclic, both PSI and PSII are involved
  2. photolysis is only required in non-cyclic
  3. oxygen is only produced in non-cyclic
  4. NADPH is only synthesised in non-cyclic
  5. ATP produced in cyclic is used by the cell, whereas ATP produced in non-cyclic is used for the light-independent reactions
30
Q

explain part 1 of the Calvin cycle

A

ribulose bisphosphate reacts with CO2 to produce two glycerate 3-phosphate molecules. the reaction is catalysed by rubisco enzymes

31
Q

what enzyme catalyses the reaction between ribulose bisphosphate and CO2?

A

rubisco

32
Q

what products are produced when ribulose bisphosphate and CO2 react?

A

two glycerate 3-phosphate molecules

33
Q

explain part 2 of the Calvin cycle

A

glycerate 3-phosphate molecules are reduced to triose phosphate. hydrolysis of ATP provides energy for reaction. reduced NADP provides H+ ions for the reaction.

34
Q

explain part 3 of the Calvin cycle

A

triose phosphate is used to regenerate ribulose bisphosphate or make hexose sugars. hydrolysis of ATP provides energy for this reaction

35
Q

how many turns of the Calvin cycle does it take to make one hexose sugar?

A

6

36
Q

how many carbon atoms are in a ribulose bisphosphate molecule?

A

5

37
Q

how many carbon atoms are in each glycerate 3-phosphate molecule?

A

3

38
Q

how many carbon atoms are in each triose phosphate molecule?

A

3

39
Q

how many ATP molecules are hydrolysed in one turn of the Calvin cycle?

A

3

40
Q

how many NADPH molecules are used in one turn of the Calvin cycle?

A

2