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Biology A-level > 5A Photosynthesis and Respiration > Flashcards

5A Photosynthesis and Respiration Flashcards

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1
Q

Why do plants need energy?

A
  • Photosynthesis
  • Active transport
  • DNA replication
  • Cell division
  • Protein synthesis
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2
Q

Why do animals need energy?

A
  • Muscle contraction
  • Maintaining body temp
  • Active transport
  • DNA replication
  • Cell division
  • Protein synthesis
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3
Q

What does photosynthesis do?

A

It is the process where energy from light is used to make glucose from water and carbon dioxide

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4
Q

What is the overall equation for photosynthesis?

A

6CO2 + 6H2O + Energy –> C6H12O6 + 6O2

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5
Q

How is the energy that is produced from photosynthesis stored?

A

It is stored in the glucose that is made until the plant releases it by respiration

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6
Q

How do animals obtain glucose?

A

By eating plants (or other animals)

They then respire the glucose to release energy

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7
Q

How do cells release the energy from glucose?

A

By respiration

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8
Q

What is the energy from glucose used for in cells?

A

It is used to power all the biological processes in a cell

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9
Q

What are the two types of respiration?

A

Aerobic - respiration using oxygen

Anaerobic - respiration without oxygen

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10
Q

What is the equation for aerobic respiration?

A

C6H12O6 + 6O2 –> 6CO2 +6H2O + Energy

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11
Q

What is C6H12O6?

A

Glucose

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12
Q

What does anaerobic respiration in plants and yeast produce?

A

Ethanol, CO2 and releases energy

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13
Q

What does anaerobic respiration produce in animals?

A

Lactate and energy

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14
Q

What is ATP used for in a cell?

A

It is the immediate source of energy

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15
Q

Why do cells use ATP for energy?

A

As a cell can’t get its energy directly from glucose

So energy released from glucose is used to make ATP

ATP carries energy around the cell where it’s needed

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16
Q

How is ATP made?

A

It is synthesised via a condensation reaction between ADP and an inorganic phosphate, using energy from an energy releasing-reaction

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17
Q

Which enzyme catalyses the formation of ATP?

A

ATP synthase

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18
Q

Where is ATP hydrolysed?

A

In the part of the cell that needs energy

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19
Q

What happens when ATP is hydrolysed (broken down)?

A

It is hydrolysed into ADP and inorganic phosphate

Chemical energy is released from the phosphate bond and is used by the cell

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20
Q

Which enzyme catalyses the breakdown of ATP?

A

ATP hydrolase

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21
Q

Where is the energy stored in ATP?

A

In the phosphate bend, it is released when this bond is broken

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22
Q

Once ATP has been broken down, what happens the the ADP and the inorganic phosphate?

A

They’re recycled and the process starts again

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23
Q

What are 6 useful properties of ATP?

A
  1. Small manageable amount of energy released at a time
  2. Small and soluble molecule
  3. Easily broken down
  4. Can be quickly re-meade
  5. Can make other molecules more reactive
  6. Can’t pass out of the cell
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24
Q

Why is it useful that ATP only releases small, manageable amounts of energy at a time?

A

So no energy is wasted as heat

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25
Q

Why is it useful that ATP is a small soluble molecule?

A

So it can be easily transported around the cell

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26
Q

Why is it useful that ATP is easily broken down?

A

So energy can be released instantaneously

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27
Q

How can ATP make other molecules more reactive?

A

By transferring one of its phosphate groups to them (phosphorylation)

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28
Q

Why is it useful that ATP can’t pass out of the cell?

A

So the cell always has an immediate supply of energy

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29
Q

What is a metabolic pathway?

A

A series of small reactions controlled by enzymes

e.g. respiration or photosynthesis

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30
Q

What is phosphorylation?

A

Adding phosphate to a molecule

e.g. ADP is phosphorylated to ATP

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31
Q

What is photophosphorylation?

A

Adding phosphate to a molecule using light

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32
Q

What is photolysis?

A

The splitting (lysis) of a molecule using light (photo) energy

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33
Q

What is photionisation?

A

When light energy ‘excites’ electrons in an atom/molecule, giving them more energy & causing them to be released

The release of electrons causes the atom or molecule to become a positively-charged ion

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34
Q

What is hydrolysis?

A

The splitting (lysis) of a molecule using water (hydro)

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35
Q

What is decarboxylation?

A

The removal of CO2 from a molecule

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36
Q

What is dehydrogenation?

A

The removal of hydrogen from a molecule

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37
Q

What is a redox reaction?

A

Reactions that involve oxidation and reduction

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38
Q

What happens when something is reduced?

A

It has gained electrons

May have gained hydrogen or lost oxygen

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39
Q

What happens when something is oxidised?

A

It has lost electrons

May have lost hydrogen or gained oxygen

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40
Q

Give 2 example of where coenzymes are used

A
  • Photosynthesis

- Respiration

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41
Q

What is a coenzyme?

A

A molecule that aids the function of an enzyme

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42
Q

How do coenzymes work?

A

By transferring a chemical group from one molecule to another

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43
Q

What is the coenzyme used in photosynthesis called?

A

NADP

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44
Q

What does NADP do?

A

NADP transfers hydrogen from one molecule to another

This means it can REDUCE (give hydrogen to) or OXIDISE (take hydrogen from) a molecule

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45
Q

What are the coenzymes used in respiration?

A
  • NAD
  • Coenzyme A
  • FAD
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46
Q

What do NAD and FAD do in respiration?

A

They transfer hydrogen from one molecule to another

This means they can REDUCE (give hydrogen to) or OXIDISE (take hydrogen from) a molecule

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47
Q

What does coenzyme A do in respiration?

A

It transfers acetate between molecules

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48
Q

Where does photosynthesis take place in the cell?

A

In the chloroplasts

They are flattened organelles , surrounded by a double membrane

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49
Q

What are thylakoids?

A

Fluid-filled sacs found in the chloroplasts

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50
Q

What are grana?

A

Stacks of thylakoids

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51
Q

How are grana linked?

A

By bits of thylakoid membrane called lamellae

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52
Q

Where are the photosynthetic pigments found?

A

In the thylakoid membranes in chloroplasts

They are attached to proteins

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53
Q

Give 3 examples of photosynthetic pigments

A
  • Chlorophyll A
  • Chlorophyll B
  • Carotene
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54
Q

What are photosynthetic pigments?

A

They are coloured substances that absorb the light energy needed for photosynthesis

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55
Q

What is the protein and photosynthetic pigment called when they’re together?

A

A photosystem

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56
Q

How many photosystems are used by plants to capture light energy?

A

2

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57
Q

What are the names of the photosystems used by plants?

A
  • Photosystem 1 (or PSI)

- Photosystem 2 (or PSII)

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58
Q

What wavelength of light does PSI absorb best?

A

700 nm

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59
Q

What wavelength of light does PSII absorb best?

A

680 nm

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60
Q

What is the stroma?

A

It is a gel-like substance contained within the inner membrane of the chloroplast and it surround the thylakoids

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61
Q

What does the stroma contain?

A
  • Enzymes
  • Sugars
  • Organic acids
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62
Q

What happens to carbohydrates produced by photosynthesis?

A

They are not used up straight away, they are stored as starch grains in the stroma

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63
Q

What are the 2 stages that photosynthesis can be split into?

A
  • The light dependent reaction reaction

- The light independent reaction

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64
Q

What does the light dependant reaction in photosynthesis need?

A

Light energy, as suggested by the name

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65
Q

Where does light dependant photosynthesis take place?

A

In the thylakoid membranes of the chloroplasts

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66
Q

What happens to H2O in the light dependent reactions?

A

it is oxidised into O2

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67
Q

Where is light absorbed in the light dependant photosynthesis reaction?

A

By the chlorophyll (and other photosynthetic pigments) in the photosystems

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68
Q

How does chlorophyll become photoionised?

A

Light energy (absorbed by the chlorophyll) excites the electrons in the chlorophyll

This leads to their eventual release from the molecule - the chlorophyll has been photoionised

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69
Q

What is the energy produced from the light dependant photosynthesis reaction used for?

A
  • Some is used to add a phosphate group to ADP to make it ATP
  • Some is used to reduce NADP to form reduced NADP
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70
Q

What is the role of the ATP and NADP produced by the light dependent photosynthesis reaction?

A

ATP –> transfers energy

NADP –> transfers hydrogen to the light-independent reaction

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71
Q

What is another name for the light independent reaction?

A

The Calvin cycle

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72
Q

Does the calvin cycle use light energy?

A

It doesn’t use light energy directly

But it does rely on the products of the light dependent reaction

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73
Q

Where does the light independent reaction take place?

A

In the stroma of the chloroplast

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74
Q

How is ATP and reduced NADP used in the light independent reaction?

A

They supply the energy & hydrogen to make simple sugars from CO2

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75
Q

In the light dependent reaction how is ATP made?

A

By photophosphorylation

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76
Q

In the light dependent reaction, what is the energy from the photoionisation of chlorophyll used for?

A
  • Making ATP from ADP and inorganic phosphate
  • Making reduced NADP from NADP
  • Splitting water into protons (H+ ions), electrons and oxygen
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77
Q

What is the process of splitting water into protons (H+ ions), electrons and oxygen called?

A

Photolysis

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78
Q

What is the process of making ATP from ADP and inorganic phosphate called?

A

Photophosphorylation

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79
Q

What are the two type of photophosphorylation in the light independent reaction called?

A
  • Non-cyclic

- Cyclic

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80
Q

What does non-cyclic photophosphorylation produce?

A

ATP, reduced NADP and O2

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81
Q

What are the photosystems in the thylakoid membranes linked by?

A

Electron carriers

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82
Q

What are electron carriers?

A

Proteins that transfer electrons

83
Q

What is an electron transport chain?

A

A chain of proteins through which excited electrons flow

formed by the photosystems and electron carriers

84
Q

What are the main stages of light dependent photosynthesis?

A

1) Light energy excites electrons in chlorophyll
2) Photolysis of water produces protons (H+ ions), electrons and O2
3) Energy from the excited electrons makes ATP…
4) …and generates reduced NADP

85
Q

What happens to excite the electrons in chlorophyll in photosynthesis?

(stage 1 of light dependent photosynthesis)

A
  • Light energy absorbed by PSII
  • Light energy excites electrons in chlorophyll
  • Electrons move to a higher energy level (have more energy)
  • The high-energy electrons are released from the chlorophyll & moved down the electron transport chain to PSI
86
Q

What happens for the photolysis of water in photosynthesis?

stage 2 of light dependent photosynthesis

A
  • As excited electrons from chlorophyll leave PSII, they must be replaced
  • Light energy splits water into protons (H+ ions), electrons & oxygen - photolysis
87
Q

What is the equation for the photolysis of water in the chlorophyll?

A

H2O –> 2H+ + 1/2O2

88
Q

How does the energy from excited electrons make ATP in photosynthesis?

(stage 3 of light dependent photosynthesis)

A
  • Excited electrons lose energy as they move down the electron transport chain
  • Lost energy is used to transport protons into the thylakoid so the thylakoid has a higher conc. of protons than the stroma
  • This forms a protein gradient across the thylakoid membrane
  • Protons move down their conc. gradient, into the stroma, via the enzyme ATP synthase, which is embedded in the thylakoid membrane
  • The energy from this moment combines ADP & inorganic phosphate to form ATP
89
Q

How is reduced NADP produced from ATP in photosynthesis?

stage 4 of light dependent photosynthesis

A
  • Light energy is absorbed which excites the electrons again to an even higher energy level
  • Finally, the electrons are transferred to NADP, along with a proton (H+ ions) from the stroma - to form reduced NADP
90
Q

What is chemiosmosis?

A

The process of electrons flowing down the electron transport chain and creating a proton gradient across the membrane to drive ATP synthesis

It’s described by the chemiosmotic theory

91
Q

What is the light-independent reaction (photosynthesis) also called?

A

The Calvin Cycle

92
Q

Where does the Calvin Cycle (light-independent reaction) take place?

A

The stroma on the chloroplast

93
Q

What does the Calvin Cycle make and what from?

A

A molecule called triose phosphate

From CO2 and ribulose bisphosphate

94
Q

What is ribulose bisphosphate?

A

A 5-carbon compound

95
Q

What can ribulose bisphosphate be used for?

A

To make glucose and other useful organic substances

96
Q

What does the Calvin Cycle need to keep it going?

A

It needs ATP and H+ ions

97
Q

What is the Calvin Cycle like?

A

There are a few steps in the cycle and the reactions are in a linked cycle which means the starting compound, ribulose bisphosphate, is regenerated

98
Q

What are the 3 main stages in the Calvin Cycle?

A

1 - CO2 is combined with the ribulose bisphosphate to form two molecules of glycerate 3-phosphate

2 - ATP and reduced NADP are required for the reduction of GP to triose phosphate

3 - Ribulose bisphosphate is regenerated

99
Q

What happens in the first stage of the Calvin Cycle (where CO2 is added)?

A
  • CO2 enters leaf through stomata & diffuses into the stroma of the chloroplast
  • CO2 is combined with ribulose bisphosphate (RuBP), a 5 carbon compound
  • Unstable 6 carbon molecule is made, it quickly breaks down two molecules of a 3-carbon compound called glycerate 3-phosphate (GP)
100
Q

What happens in the second stage of the Calvin Cycle (ATP and reduced NADP used)?

A
  • Hydrolysis of ATP (from light-dependent reaction) provides energy to turn 3-carbon compound (GP), into a different 3-carbon compound, triose phosphate (TP)
  • This reaction needs H+ ions which come from reduced NADP (from L-D reaction), reduced NADP is recycled to NADP
  • Some triose phosphate is converted to useful organic compounds (e.g. glucose) & some continues in Calvin Cycle to regenerate RuBP
101
Q

What happens in the third stage of the Calvin Cycle (Ribulose bisphosphate is regenerated)?

A
  • 5/6 molecules of TP produced aren’t used to make hexose sugars, but to regenerate RuBP
  • Regenerating RuBP uses the rest of the ATP produced by the L-D reaction
102
Q

What are TP and GP converted to after the Calvin Cycle?

A

They are converted into useful organic substances like glucose

103
Q

What is the Calvin Cycle the starting point for?

A

It is the starting point for making all the organic substances plants need

104
Q

What are triose phosphate and glycerate 3-phosphate (from the Calvin Cycle) used for?

A

To make carbohydrates, lipids and amino acids

105
Q

What are the general optimum conditions for photosynthesis?

A
  • High light intensity of a certain wavelength
  • Temperature around 25 degrees
  • Carbon dioxide at 0.4%
106
Q

Why is light important for photosynthesis?

A

Light is needed to provide the energy for the light-dependent reaction

The higher the intensity of the light, the more energy it provides

107
Q

What are the 3 photosynthetic pigments?

A
  • Chlorophyll a
  • Chlorophyll b
  • carotene
108
Q

What types of light can the photosynthetic pigments absorb?

A

They can only absorb the red and blue light in sunlight

109
Q

Why is green light not absorbed and used for photosynthesis?

A

Green light is reflected as the chlorophyll is green, which is why the plant appears green

110
Q

What are the enzymes involved in photosynthesis?

A

ATP synthase and rubisco

111
Q

Why does the temperature for photosynthesis have to be 25 degrees?

A

The enzymes involved cannot function below 10 degrees and will denature above 45 degrees

112
Q

What happens to the stomata when the temperature is too high?

A

High temperatures cause the stomata to close to avoid losing too much water

This caused photosynthesis to slow down because less CO2 enters the leaf when stomata are closed

113
Q

What % of the atmosphere is CO2

A

0.04%

114
Q

Why is the optimum amount of CO2 0.4% and not 0.04%?

A

Increasing it to 0.4% gives a higher rate of photosynthesis but any higher than this the stomata will close

115
Q

How are carbohydrates made during the Calvin Cycle?

A

Also known as hexose sugars

Are made by joining two triose phosphate molecules

Larger carbohydrates are made by joining hexose sugars together in different ways

116
Q

How are lipids made during the calvin cycle?

A

They are made using glycerol - which is synthesised from triose phosphate & fatty acids

these are synthesised from glycersate 3-phosphate

117
Q

How are amino acids made during the calvin cycle?

A

Some amino acids are made from glycerate 3-phosphate

118
Q

How many times does the calvin cycle need to turn to make one hexose sugar?

A

Six times

119
Q

Why does the calvin cycle have to turn 6 times to make one hexose sugar?

A

1) 3 turns produce 6 molecules of triose phosphate (TP) - two molecules of TP are produced for every one CO2 molecule used
2) 5/6 TP molecules used to regenerate ribulose bisphosphate (RuBP)
3) This means for 3 turns 1 TP is produced that’s used to make hexose sugar
4) Hexose sugar has 6 carbons, so 2 TP needed to form one hexose sugar
5) Means the cycles must turn 6 times to produce 2 molecules of TP that can be used to make 1 hexose sugar
6) 6 turns of the cycle need 18 ATP & 12 reduced NADP from the light-dependent reaction

120
Q

How much ATP and reduced NADP is needed for 6 turns of the Calvin Cycle?

A
  • 18 ATP

- 12 reduced NADP

121
Q

What are the ideal conditions for photosynthesis?

A
  • High light intensity of a certain wavelength
  • Temp around 25 degrees
  • CO2 at 0.4%
122
Q

Why is light important for photosynthesis?

A

Light is needed to provide the energy for the light-dependent reaction

The higher the intensity of the light, the more energy it provides

123
Q

What are the 3 photosynthetic pigments?

A
  • Chlorophyll a
  • Chlorophyll b
  • Carotene
124
Q

What are the light wavelengths that photosynthetic pigments can absorb?

A

Red and blue light in sunlight

125
Q

Why can’t plants absorb green light?

A

It is reflected, as the chlorophyll is green so it cannot be absorbed

This is why plants look green

126
Q

Give two example of enzymes used in photosynthesis

A

ATP synthase and rubisco

127
Q

Why must the temperature be around 25 degrees for photosynthesis?

A

Photosynthesis involves enzymes

If the temp falls below 10 degrees the enzymes become inactive

If the temp is more than 45 degrees the enzymes with start to denature

Also affects stomata

128
Q

What happens to stomata on plants if the temperature becomes too high

A

High temps cause stomata to close to avoid losing too much water

Causes photosynthesis to slow down as less CO2 enters the leaf when the stomata are closed

129
Q

How much CO2 is in the atmosphere?

A

It makes up 0.04% of gases in the atmosphere

130
Q

Why is the optimum CO2 levels 0.4% and not 0.04%?

A

Increasing the levels to 0.4% gives a higher rate of photosynthesis

But any higher and the stomata would close

131
Q

Why is water key to photosynthesis?

A

Plants need a constant supply of water

  • Too little and photosynthesis would stop
  • Too much and the soil becomes waterlogged
132
Q

Why is it bad for the plant if there is too much water?

A

The soil becomes waterlogged

It reduces the uptake of minerals ie magnesium which is needed to make chlorophyll a

133
Q

What are the limiting factors of photosynthesis?

A

Light, temperature and CO2

134
Q

What happens if one of the limiting factors of photosynthesis is too high or low?

A

It will limit photosynthesis (slow it down)

Even if the other two factors are at the perfect level it won’t make any difference due to the one at the wrong level

135
Q

On a warm sunny day what would be the limiting factor for photosynthesis?

A

CO2

136
Q

At night what is the limitng factor for photosynthesis?

A

The light intensity

137
Q

What is the saturation point in photosynthesis?

A

Where a factor is no longer limiting the reaction - something else has to become the limiting factor

138
Q

What do growers use info about limiting factors for?

A

To increase plant growth

139
Q

How do farmers/growers control CO2 conc. ina greenhouse?

A

CO2 is added to the air

e.g. by burning a small amount of propane in a CO2 generator

140
Q

How do farmers/growers control light intensity in a greenhouse?

A

Light can get through the greenhouse glass

Lamps provide light at night time

141
Q

How do farmers/growers control temperature in a greenhouse?

A

Glasshouses trap heat energy from sunlight which warms the air

Heaters & cooling systems can also be used to keep a constant optimum temp & air circulation systems make sure the temp is even throughout glasshouse

142
Q

What are the two types of respiration?

A
  • Aerobic

- Anaerobic

143
Q

Do both areobic & anaerobic respiration both produce ATP?

A

They both do - but anaerobic produces less

144
Q

What do both aerobic and anaerobic start with?

A

They both start with glycolysis but the stages can differ

145
Q

What does glycolysis make?

A

It makes pyruvate from glucose

146
Q

What does glycolysis involve?

A

It involves splitting one molecule of glucose (with 6 carbons) into two smaller molecules of pyruvate (3C)

147
Q

Where does glycolysis happen?

A

The process happens in the cytoplasm of cells

148
Q

Is glycolysis anaerobic or aerobic?

A

It is an anaerobic process

It is the first stage of both aeorobic & anaerobic respiration and doesnt need oxygen

149
Q

What are the two stages in glycolysis?

A
  • Phosphorylation

- Oxidation

150
Q

What happens in phosphorylation (first stage of glycolysis)?

A

1 - Glucose is phosphorylated using a phosphate from a molecule of ATP. This creates 1 molecule of glucose phosphate and 1 molucule of ADP

2 - ATP is then used to add another phosphate, forming hexose bisphosphate

3 - Hexose bisphosphate is then split into 2 molecules of triose phosphate

151
Q

What happens in oxidation (second stage of glycolysis)?

A

1 - Triose phospahte is oxidised (loses hydrogen), forming 2 molecules of pyruvate

2 - NAD collects the hydrogen ions, forming 2 reduced NAD

3 - 4 ATP are produced, but 2 were used up in stage 1, so there’s a net gain of 2 ATP

152
Q

What is the overall reaction for glycolysis?

A

ATP is used to phosphorylate glucose to triode phosphate

Then triose phosphate is oxidised, releasing ATP

Overall there’s a net gain of 2 ATP and 2 reduced NAD

153
Q

What are the products of glycolysis?

A

2 reduced NAD

2 molecules of pyruvate

2 ATP

154
Q

Where does the reduced NAD from glycolysis go to?

A

It goes to oxidative phosphorylation

155
Q

Where do the two pyruvate molecules from glycolysis go?

A

They are actively transported into the matrix of the mitochondria for the link reaction

156
Q

What happens in anaerobic respiration after glycolysis?

A

Pyruvate is converted to either ethanol or lactate depending on whether it’s an animal or a plant

157
Q

What happens to pyruvate in anaerobic respiration in plants?

A
  • It is reduced to ethanal first (CO2 is released)

- Then ethanol is produced (it is reduced by reduced NAD when it turns into NAD)

158
Q

What is anaerobic respiration in plants called?

A

Alcoholic fermentation

159
Q

What is anaerobic respiration in animals called?

A

Lactate fermentation

160
Q

What happens in anaerobic respiration in animals?

A

Pyruvate is reduced to lactic acid - it is reduced by reduced NAD being oxidised

161
Q

What does the link reaction do?

A

It converts pyruvate to acetyl coenzyme A

162
Q

Is ATP produced in the link reaction?

A

No it is not

163
Q

What is the order of respiration?

A

1) Glycolysis
2) Link reaction
3) Krebs cycle
4) Oxidative phosphoralation

164
Q

What are the products of the krebs cycle?

A
  • 1 coenzyme A
  • 2 oxaloacetate
  • 2 CO2
  • 1 ATP
  • 3 reduced NAD
  • 1 reduced FAD
165
Q

What does oxidative phosphorylation produce lots of?

A

ATP

166
Q

Explain the whole process of oxidative phosphorylation

A

1) Hydrogen atoms released from FAD & NAD and split into protons and electrons
2) Electrons move down transport chain
3) Energy from this is used to pump protons from mitochondrial matrix into intermembrane space
4) Concentration of protons is higher in intermembrane space so forms a gradient
5) Protons move down the gradient through ATP synthase (makes ATP from ADP and P)
6) At end of transport chain protons, electrons and O2 form water

167
Q

In oxidative phosphorylation where are the hydrogen atoms (protons and electrons) released from?

A

Reduced NAD and FAD

168
Q

What happens at the electric transport chain in oxidative phosphorylation?

A

Electrons move down transport chain losing energy at each carrier?

169
Q

What gradient is formed in oxidative phosphorylation from protons?

A

Electrochemical gradient

170
Q

How do the protons go through ATP synthase?

A

They diffuse

171
Q

What is the process of ATP production driven by movement of H+ ions across a membrane called?

A

Chemiosmosis

172
Q

How much ATP can be made from 1 glucose molecule?

A

32

173
Q

What molecules are produced at glycolysis?

A

2 ATP

2 reduced NAD

174
Q

What sort of reactions occur in the Krebs cycle?

A

A series of oxidation-reduction reactions

175
Q

What molecules are produced at the krebs cycle?

A

2 ATP
6 reduced NAD
2 reduced FAD

176
Q

What happens in the first stage of the Krebs cycle?

A

1 - Acetyl CoA from link reaction combines ith 4-carbon molecule (oxaloacytate) to form a 6-carbon molecule (citrate)

2 - CoA goes back to link reaction to be used again (acetyl group is used)

177
Q

How much ATP is made for every reduced FAD?

A

1.5 ATP from every reduced FAD

178
Q

Explain the process of the link reaction

A

1 - Pyvurvate is decarboxylated (carbon atom removed from pyruvate in the form of CO2)

2 - Pyruvate is oxidised to form acetate & NAD is reduced to form reduced NAD

3 - Acetate is combined with coenzyme A (CoA) to form acetyl coenzyme A (acetyl CoA)

4 - No ATP produces in this reaction

179
Q

What are the products of the link reaction?

A
  • Acetyl CoA
  • CO2
  • Reduced NAD
180
Q

Which stage in respiration is oxidative phosphorylation?

A

The fourths stage (last stage)

181
Q

Why does the link reaction happen twice for every glucose molecule?

A

Two pyruvate molecules are made for every glucose molecule that enters glycolysis

Therefore the link reactiona and the Krebs cycle happen twice for every glucose molecule

182
Q

After the link reaction, what has been produced from one molecule of glucose (in total)?

A
  • Two molecules of a CoA (go to Krebs cycle)
  • Two CO2 molecules (released as waste products)
  • Two molecules of reduced NAD (go to oxidative phosphorylation)
183
Q

What does the Krebs cycle produce?

A

Reduced coenzymes and ATP

184
Q

Where does the Krebs cycle take place?

A

In the matrix of the mirochondria

185
Q

What sort of reactions occur in the Krebs cycle?

A

A series of oxidation-reduction reactions

186
Q

What disease can affect ATP production?

A

mitochondrial disease

187
Q

How is respiration affected by mitochondrial disease?

A

Affect how proteins function in the krebs cycle and oxidative phosphorylation

188
Q

What does mitochondrial disease lead to?

A
  • Increase in anaerobic respiration (makeup for less ATP)
  • Lots of lactate produced, causes muscle fatigue and weakness
  • Some lactate diffuses into blood stream, leading to high concentration of lactate in the blood
189
Q

What other respiratory substrates can be used in aerobic respiration?

A

Fatty acids, lipids and amino acids

190
Q

How many times does the Krebs cycle happen per pyruvate molecule?

A

Once for every pyruvate molecule

So twice for every glucose molecule

191
Q

What happens in the first stage of the Krebs cycle?

A

1 - Acetyl CoA from link reaction combines ith 4-carbon molecule (oxaloacytate) to form a 6-carbon molecule (citrate)

2 - CoA goes back to link reaction to be used again (acetyl group is used)

192
Q

Which stage in respiration is glycolysis?

A

The first stage

193
Q

Which stage in respiration is the link reaction?

A

The second stage

194
Q

Which stage in respiration is the Krebs cycle?

A

The thid stage

195
Q

Which stage in respiration is oxidative phosphorylation?

A

The fourths stage (last stage)

196
Q

What happens in the second part of the Krebs cycle?

A

1 - 6C cirtate molecule converted to 5C molecule (lost as CO2)

2 - Decarboxylation occurs (caused CO2 to be removed)

3 - Dehydrogenation occurs - hydrogen is removed

4 - Lost hydrogen is used to produce reduced NAD from NAD

197
Q

What happens in the third stage (final) of the Krebs cycle?

A

1 - 5C molecule converted to 4C

2 - Decarboxylation & dehydrogenation occur, produces 1 molecule reduced FAD & two reduced NAD

3 - ATP produced - direct transfer of phosphate group from intermediate compund to ADP - citrate converted to oxaloacetate

198
Q

What happens overall in the Krebs cycle?

A

1a - Acetyl CoA from link reaction combines ith 4-carbon molecule (oxaloacytate) to form a 6-carbon molecule (citrate)

1b - CoA goes back to link reaction to be used again (acetyl group is used)

2a - 6C cirtate molecule converted to 5C molecule (lost as CO2)

2b - Decarboxylation occurs (caused CO2 to be removed)

2c - Dehydrogenation occurs - hydrogen is removed

2d - Lost hydrogen is used to produce reduced NAD from NAD

3a - 5C molecule converted to 4C

3b - Decarboxylation & dehydrogenation pccur, produces 1 molecule reduced FAD & two reduced NAD

3c - ATP produced - direct transfer of phosphate group from intermediate compund to ADP - citrate converted to oxaloacetate

LOOK AT TEXTBOOK!!!! piss of lucy

199
Q

What organisms are used to investigate factors affecting respiration?

A

yeast

200
Q

Why are yeast used to investigated respiration?

A

When respire both aerobically and anaerobically CO2 is produced, this can used used to test the respiration rate

201
Q

How do your measure CO2 production?

A

gas syringe

202
Q

Explain process of temperature on aerobic respiration experiment?

A

1) put known volume and substrate solution in a tube, add buffer to maintain PH
2) place test tube in water bath to temperature being tested, leave for 10 mins so temperature of substrate can stabilize
3) add dried yeast and stir for 2 mins, until dissolved
4) put bung with tube attached to gas syringe in top of tube, should be at 0
5) start stop watch as soon as bung on test tube
6) at intervals record volume of CO2
7) repeat 3 times with different temperatures and one with no yeast as a control

203
Q

Explain process of temperature on anaerobic respiration experiment?

A

1) put known volume and substrate solution in a tube, add buffer to maintain PH
2) place test tube in water bath to temperature being tested, leave for 10 mins so temperature of substrate can stabilize
3) add dried yeast and stir for 2 mins, until dissolved
4) trickle liquid paraffin down inside of test tube so completely covers surface, stops oxygen
5) start stop watch as soon as bung on test tube
6) at intervals record volume of CO2
7) repeat 3 times with different temperatures and one with no yeast as a control

Biology A-level (20 decks)

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