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Biology > 5A (photosynthesis and respiration) > Flashcards

5A (photosynthesis and respiration) Flashcards

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1
Q

why is energy important?

A

plants/ animals need energy for biological processes to occur so organism doesnt die
- photosynthesis, active transport, DNA replication, cell division, prot synthesis, muscle contraction, maintain body temp

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2
Q

what is the equation for photosynthesis?

A

6CO2 + 6H2O -> C6H12O6 + 6O2

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3
Q

what is the equation for aerobic respiration?

A

C6H12O6 + 6O2 -> 6CO2 + 6H2O

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4
Q

what is the equation for anaerobic respiration in humans?

A

C6H12O6 -> lactate

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5
Q

what is the equation for anaerobic respiration in plants/yeast?

A

C6H12O6 -> ethanol + CO2

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6
Q

what are the properties of ATP?

A
  • stores/ releases manageable amount of energy at a time (no energy wasted as heat)
  • small, soluble so easily transported
  • easily broken down so energy released instantaneously
  • can be quickly remade
  • can make other molecules more reactive through phosphorylation
  • cant pass out of cell so cell always has immediate supply of energy
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7
Q

what is the compensation point for light intensity?

A

particular level of light intensity where rate of respiration= rate of photosynthesis

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8
Q

how can you work out the compensation point for a plant?

A

measure rate O2 is being produced and used by plant at diff light intensities
compensation point is light intensity at which oxygen is being used as quickly as it is produced (0 net oxygen generation)
could also measure CO2

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9
Q

describe the structure of chloroplasts

A

small, flat organelles surrounded by double membrane
thylakoids are stacked into grana which are linked by lamella
contain photosynthetic pigments (absorb light energy for photosynthesis)
pigment is found in thylakoid membranes and are attached to proteins. protein and pigment is a photosystem (2 photosystems in plant)
stroma contains enzymes, sugars, organic acids
carbohydrates produced in photosynthesis that arent used straight away are stored as starch grains in stroma

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10
Q

redox reactions

A

reduced- gained electrons, gained hydrogen, lost oxygen
oxidised- lost electrons, lost hydrogen, gained oxygen

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11
Q

what is a coenzyme?

A

molecule that aids function of enzyme
they transfer chemical group from one molecule to another
eg NADP

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12
Q

what happens in the light dependent reaction? where does it take place?

A

occurs in thylakoids
light absorbed by chlorophyll in photosystems which excites the electrons giving them more energy and they eventually leave molecule (photoionisation) chlorophyll now +
some energy released is used to produce ATP and some used to form reduced NADP
ATP transfers energy and NADP transfers hydrogen to light independent reaction
in process, H2O oxidised to O2

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13
Q

what is the light independent reaction? where does it take place?

A

occurs in stroma
ATP and reduced NADP supply energy and hydrogen to make glucose from CO2
Calvin cycle

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14
Q

what is the energy resulting from the photoionisation of chlorophyll used for?

A

making ATP through phosphorylation
making reduced NADP from NADP
splitting water into protons, electrons and oxygen (photolysis)

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15
Q

what is non-cyclic phosphorylation?

A

produces ATP, reduced NADP, O2
photosystems are linked by electron carriers and this creates an electron transport chain

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16
Q

what are the processes in noncyclic phosphorylation?

A

1) Light energy excites electrons in chlorophyll- light energy absorbed by PS2 and this excites electrons in chlorophyll so they move to higher energy level and are released from chlorophyll and move down electron transport chain to PS1

2) photolysis of water produces protons, electrons, oxygen- excited electrons that leave must be replaced. light energy splits water into protons, electrons and oxygen in photolysis H2O -> 2H+ + 1/2O2

3) energy from exited electrons makes ATP- exited electrons lose energy as they move down e- transport chain. this energy is used to transport protons to thylakoids so thylakoid has higher conc of protons than stroma. this forms proton grad across thylakoid membrane which protons move down into the stroma via ATP synthase which is embedded in thylakoid membrane. energy from this movement combines ADP and Pi to form ATP

4) Energy from exited electrons generates reduced NADP- light energy absorbed by PS1 which excites electrons again to an even higher level. finally, electrons transferred to NADP with proton from stroma to form reduced NADP

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17
Q

what is the electron transport chain?

A

chain of proteins through which exited electrons flow

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18
Q

what is an electron carrier?

A

protein that transfers electrons

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19
Q

what is chemiosmotic theory?

A

the process of electrons flowing down electron gradient across membrane to drive ATP synthesis

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20
Q

what is cyclic phosphorylation?

A

Produces ATP and only uses PS1
cyclic because electrons from chlorophyll molecule are passed to NADP but are passed back to PS1 via electron carriers. electrons recycled repeatedly . doesnt produce reduced NADP or oxygen and only small amounts of ATP produced

21
Q

what is the Calvin cycle

A

takes place in stroma
makes triose phosphate from CO2 and ribulose biphosphate
TP can be used to make glucose/ other useful organic substances

22
Q

describe the Calvin cycle

A

1) formation of glycerate-3-phosphate
CO2 enters through stomata and diffuses into stroma where it combines w RuBP catalysed by rubisco. forms unstable 6 carbon compound which breaks into 2 molecules of gycerate-3-phosphate (GP)

2) formation of triose phosphate
hydrolysis of ATP from ldr provides energy to reduce GP into TP (also 3 carbon). this requires H+ which come from reduced NADP. some TP converted into useful organic compounds, some continue in calvin cycle to regenerate RuBP

3) regeneration of RuBP
5/6 molecules of TP produced are used to regenerate RuBP. this uses rest of ATP produced by ldr

23
Q

what is a hexose sugar? how many times does the Calvin cycle need to occur to make one hexose sugar? why?

A

hexose sugar is 6-carbon sugar made from 2 TP
cycle needs to turn 6 times to make 1 hexose sugar as 3 turns produces 6 TP (2 made for every CO2). 5/6 used to regenerate RuBP so 3 turns, only 1 TP that is produced is used to make hexose sugar
but, 2 TPs needed so must happen 6 times

24
Q

what organic substances can be made from the Calvin cycle

A

carbohydrates- hexose sugars made from 2 TP and more complex made of multiple hexose sugars

lipids- made of glycerol synthesised from TP and fatty acids synthesised from GP

amino acids- some made from GP

25
Q

what are the ideal conditions for photosynthesis?

A

high light intensity- provide energy for ldr
certain wavelength- only some absorbed by chlorophyll

25 degrees- below 10, enzymes (ATP synthase, rubisco) inactive and above 45, denature. high temp also means stomata close to not lose water so photosynthesis slows as less CO2 enters

CO2 at 0.4% (usually 0.04 in atmosphere) increased increases ror but higher, stomata start to close

water- too little= photosynthesis has to stop, too much= waterlogged soil (reduced uptake of minerals needed to make chlorophyll)

26
Q

what are the limiting factors of photosynthesis?

A

light, temperature, carbon dioxide

27
Q

how do farmers create optimum growing conditions?

A

add CO2 by burning small amount of propane in CO2 generator
light gets in through green house glass, lamps at night
green houses trap heat energy from sun which warms air, heaters/ coolers used to keep constant temp, air circulation systems- make temp even throughout

28
Q

practicals

A
29
Q

describe the structure of mitochondria

A

folds (cristae) in inner membrane provide large sa to maximise resp

30
Q

what are the coenzymes in respiration?

A

NAD, coenzyme A, FAD
NAD and FAD transfer hydrogen between molecules so can reduce/oxidise molecules
coenzyme A transfers acetate between molecules

31
Q

what are the stages of aerobic respiration?

A

glycolysis- cytoplasm of cell
link reaction- mitochondria
Krebs cycle - mitochondria
oxidative phosphorylation- mitochondria

32
Q

what are the stages of anaerobic respiration?

A

glycolysis- cytoplasm
products of glycolysis converted to ethanol or lactate

33
Q

what are the stages of glycolysis?
what happens in each?

A

makes 2 pyruvate (3C) from glucose (6C)
1) glucose phosphorylated using pi from ATP
creates 1 molecule of glucose phosphate and 1 molecule of ADP
ATP used to add another Pi forming hexose bisphosphate which is then split in 2 triose phosphate

2) oxidation
triosephosphate is oxidised (loses H) forming 2 pyruvate
NAD collects H+ forming 2 reduced NAD. 4 ATP produced but 2 used in stage 1 so net gain of 2

34
Q

what are the products of glycolysis (aerobic resp)?

A

2 reduced NAD- go to oxidative phosphorylation
2 pyruvate- actively transported to matrix for link reaction
2 ATP (net)- used for energy

35
Q

what are the products of glycolysis (anaerobic respiration)?

A

pyruvate produced is converted to ethanol (alcoholic fermentation- plants/yeast) or lactate (lactate fermentation- animals)) using reduced NAD

this regenerates oxidised NAD so glycolysis can continue w lack of O2

see diagrams on page 40

36
Q

what is the link reaction?

A

converts pyruvate to acetyl coenzyme A

pyruvate is decarboxylated so 1C removed in form of CO2
at same time, pyruvate is oxidised to form acetate and NAD is reduced to form reduced NAD

acetate combined with CoA to form acetyl CoA

no ATP produced

37
Q

how many times do the link reaction and Krebs cycle occur per glucose molecule?

A

2 pyruvate formed per glucose molecule that enters glycolysis so link reaction and krebs cycle happen twice for every glucose

38
Q

what are the products of the link reaction?

A

2 acetyl CoA- to Krebs cycle
2 CO2- released as waste
2 reduced NAD- to oxidative phosphorylation

39
Q

what is the Krebs cycle?

A

produces reduced coenzymes and ATP
involves redox reactions in matrix of mitochondria
happens once per pyruvate

40
Q

describe the Krebs cycle

A

1) formation of 6C compound- acetyl CoA combines w 4C molecule (oxaloacetate) to form 6C molecule (citrate), coA goes back to link reaction to be reused

2) formation of 5C compound- 6C molecule is converted to 5C molecule. decarboxylation occurs where CO2 is removed. dehydrogenation also occurs- the hydrogen is used to produce reduced NAD

3) regeneration of oxaloacetate- 5C molecule is converted to 4C molecule. decarboxylation and dehydrogenation occur producing 1 reduced FAD and 2 reduced NAD. ATP produced by direct transfer of phosphate group from intermediate compound compound to ADP (substrate level phosphorylation) citrate has now been converted to oxaloacetate

41
Q

what are the products of the Krebs cycle

A

1 coA- reused in next link reaction
oxaloacetate- regenerated for use in next Krebs cycle
2CO2 reduced as waste
1 ATP- used for energy
3 reduced NAD- to oxidative phosphorylation
1 reduced FAD- to oxidative phosphorylation

42
Q

describe oxidative phosphorylation

A

1) H atoms released from reduced NAD and reduced FAD as theyre oxidised to NAD and FAD. H atoms split into H+ and e-

2) e- move down electron transport chain, losing energy at each carrier

3) this energy used by electron carriers to pump protons from matrix to intermembrane space

4) conc of protons is now higher in intermembrane space so forms electrochemical grad

5) protons move down electrochemical grad back across inner mitochondrial membrane and into matrix via ATP synthase. this movement drives synthesis of ATP from ADP and Pi

6) ATP production driven by movement of H+ ions across membrane is called chemiosmosis

7) in matrix, at end of transport chain, protons, electrons and oxygen join to form water. oxygen is the final electron acceptor

43
Q

what is oxidative phosphorylation?

A

process where energy carried by electrons from reduced coenzymes is used to make ATP
involves electron transport chain and chemiosmosis

44
Q

how does a cell make 32 ATP from 1 glucose molecule?

A

glycolysis produces 2 ATP and 2 reduced NAD (2.5 ATP each)
link reaction produces 2 reduced NAD (2.5 ATP each)
krebs cycle produces 2 ATP, 6 reduced NAD (2.5 ATP each) and 2 reduced FAD (1.5 ATP each)

45
Q

mitochondrial diseases

A

affect functioning of mitochondria
affect how proteins involved in oxidative phosphorylation or krebs cycle function, reducing ATP production
may cause anaerobic resp to increase which results in lactate production which causes muscle fatigue and weakness. some lactate will diffuse into bloodstream leading to high lactate conc in blood

46
Q

respiration experiments

A
47
Q

compare/ contrast chemiosmotic theory in photosynthesis vs respiration

A

photosynthesis
- occurs in thylakoids and stroma of chlorophyll
-water isnt produced
- photolysis of water
- only green plants
- protons pumped from stroma to thylakoid
- transforms light energy into chemical energy

respiration
- occurs in intermembrane space and matrix of mitochondria
- water is produced
- photolysis of water isnt required
- all living cells
- proton pumped from matrix into intermembrane space
- transforms chemical energy from food into ATP

both
- active transport
- transport of protons
- ATP synthase channels

48
Q

(check how to word)
why isnt all light used in photosynthesis?
or is it in food chains topic?

A
  • some reflected- green
  • not all lands on a leaf
  • gaps between chloroplasts
  • some reflected?
  • check!!!

Biology (20 decks)

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