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AQA A Level Biology > Respiration > Flashcards

Respiration Flashcards

1
Q

Why do cells respire?

A

In order to produce ATP, which stores the energy needed for metabolic reactions.

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2
Q

What process is part of both aerobic and anaerobic respiration?

A

Glycolysis

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3
Q

What is the role of oxygen in aerobic respiration?

A

Oxygen is the final electron acceptor in the oxidative phosphorylation electron transport chain. It combines with protons and electrons to form water.

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4
Q

Describe the process of glycolysis.

A
  1. Phosphorylation of glucose using 2 x ATP (to form hexose bisphosphate which then splits to form two molecules of triose phosphate)
  2. Oxidation of triose phosphate to form (2 molecules of) pyruvate (2 x NADH + 4 x ATP)
  3. Net gain of 2 x ATP
  4. NAD reduced
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5
Q

What does aerobic respiration mean?

A

With oxygen

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6
Q

What does anaerobic respiration mean?

A

Without oxygen

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7
Q

How does the structure of the mitochondria maximise rate of respiration?

A

The inner membrane of the mitochondrion provides a large surface area

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8
Q

What is a coenzyme?

A

A molecule that aids the function of an enzyme by transferring a chemical group from one molecule to another.

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9
Q

What coenzymes are used in respiration?

A

NAD, conenzyme A, FAD

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10
Q

What molecule does NAD and FAD transfer?

A

H - hydrogen allows them to reduce (give H) or oxidise (take H) a molecule.

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11
Q

What molecule does coenzyme A transfer?

A

Acetate

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12
Q

What are the 4 stages of aerobic respiration?

A
  1. Glycolysis
  2. Link Reaction
  3. The Krebs Cycle
  4. Oxidative phosphorylation
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13
Q

Where does glycolysis take place?

A

In the cytoplasm of cells

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14
Q

Where do the other three stages of aerobic respiration take place?

A

In the mitochindrial matrix

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15
Q

What can be used as a respiratory substrate in both aerobic and anaerobic respiration?

A

Glucose

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16
Q

What are the products of glycolysis?

A

2 reduced NAD
2 ATP net gain
2 Pyruvate

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17
Q

What are the products of anaerobic glycolysis - animals?

A

lactate - lactate fermentation

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18
Q

What are the products of anaerobic glycolysis - plants?

A

ethanol - alcohol fermentation
pyruvate –> (loss co2) ethanal –> (NADH –> NAD) ethanol

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19
Q

Products of the link reaction

A

2 acetyl coenzyme A
2 CO2
2 reduced NAD

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20
Q

Where do the prodcuts of the link reaction go to?

A

2 acetyl coenzyme A –> Krebs cycle
2 CO2 –> released as waste product
2 reduced NAD –> oxidative phosphorylation

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21
Q

What happens in the link reaction?

A

Converts pyruvate (from glycolysis) to acetyl coenzyme A

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22
Q

Breakdown of the link reaction?

A

Pyruvate is decarboxylated - 1C removed in the form of CO2
At the same time - pyruvate is oxidised to form acetate
NAD reduced to NADH
Acetate combined with CoA to form acetyl CoA
No ATP is produced.

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23
Q

How many times does the link reaction occur per glucose molecule?

A

Twice - because glycolysis produces 2 pyruvate

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24
Q

What are the 3 stages of the Krebs Cycle?

A

Formation of a 6C compound
Formation of a 5C compound
Regeneration of oxoloacetate

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25
Q

What reactions make up the Krebs cycle?

A

A series of oxidation-reduction reactions

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26
Q

Describe the formation of the 6 carbon compound in the Krebs Cycle

A

Acetyl coenzyme A combines with a 4C molecule (oxoloacetate) to form a 6C molecule (citrate)
Coenzyme A goes back to the link reaction

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27
Q

Equation showing the formation of 6C compound (KREBS)

A

Acetyl CoA [2C] + Oxoloacetate [4C] –> (CoA) citrate [6C]

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28
Q

Describe the formation of the 5C compound in the Krebs cycle

A

6C is converted to a 5C as decarboxylation occurs where a CO2 molecule is lost.
Dehydrogenation occurs and the H is used to produce NADH from NAD.

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29
Q

Equation showing the formation of 5C compound (KREBS)

A

Citrate [6C] –> (CO2 + (NAD –> NADH) 5C compound

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30
Q

Describe the regeneration of oxoloacetate.

A

The 5C is converted back to a 4C compound (oxoloacetate)
Decarboxylation & Dehydrogenation occur this produces 1xFADH 2xNADH
ATP is produed by the direct transfer of a phosphate group from an intermediate compound to ADP

31
Q

What is substrate-level phosphorylation?

A

When a phosphate group is directly transferred from one molecule to another.

32
Q

What are the products of the Krebs Cycle?

A

1 reduced FAD
1 ATP
3 reduced NAD
2 CO2
1 CoA
1 oxoloacetate

33
Q

What are each of the products of the Krebs Cycle used for?

A

1 reduced FAD - oxidative phosphorylation
1 ATP - used as energy
3 reduced NAD - oxidative phosphorylation
2 CO2 - waste product
1 CoA - reused in Link reaction
1 oxoloacetate - regenerated for Krebs

34
Q

What 2 processes does oxidative phosphorylation involve?

A

Chemiosmosis + Electron transfer chain

35
Q

How many steps does oxidative phosphorylation consist of?

A

7

36
Q

What is the first stage of oxidative phosphorylation?

A

Hydrogen atoms are released from FADH + NADH to form FAD + NAD
H atoms split into protons (H+) and e-

37
Q

What is the second stage of oxidative phosphorylation?

A

The electron transfer chain is made up of electron carriers. Electrons move down the ETC - losing energy at each carrier

38
Q

What is the third stage of oxidative phosphorylation?

A

The energy is used by electron carriers to pump H+ from mitochondrial matrix into the intermembrane space

39
Q

What is the intermembrane space?

A

Space between the inner and outer mitochondrial membranes

40
Q

What is the fourth stage of oxidative phosphorylation?

A

The concentration of H+ is now higher in the intermembrane space than the matrix - forms an electrochemical gradient

41
Q

What is an electrochemical gradient?

A

A concentration gradient of ions.

42
Q

What is the fifth stage of oxidative phosphorylation?

A

Protons then move down the electrochemical gradient across the inner mitochondrial membrane - into the matrix via ATP SYNTHASE.
This movement drives the synthesis of ATP from ADP and Pi.

43
Q

Where is ATP synthase found?

A

Embedded in the inner mitochondrial membrane

44
Q

What is the sixth stage of oxidative phosphorylation?

A

The process of ATP production via the movement of H+ across a membrane due to e- moving down an ETC is known as chemiosmosis.

45
Q

What is the seventh stage of oxidative phosphorylation?

A

In the mitochondrial matrix, at the end of the ETC, the H+, e- and oxygen (from blood) combine to form H2O

46
Q

What is oxygen said to be?

A

The final electron acceptor

47
Q

How many ATP are made from each reduced NAD?

A

2.5 ATP

48
Q

How many ATP are made from each reduced FAD?

A

1.5 ATP

49
Q

Protons don’t move into/out of the inner mitochondrial membrane they move…

A

across it

50
Q

How many ATP molecules can a cell make from a single molecule of glucose in aerobic respiration?

A

32 ATP

51
Q

Why do the Krebs cycle and Link reaction happen twice?

A

Because glycolysis produced 2 molecules of pyruvate.

52
Q

Glycolysis, the link reaction and the Krebs cycle are a…

A

… series of reactions which produce ATP, NADH, FADH and CO2

53
Q

The reduced coenzymes NADH and FADH are then used to produce…

A

lots of ATP in oxidative phosphorylation.

54
Q

What can mitochondrial disease affect?

A

The production of ATP

55
Q

How do mitochondrial dieases affect ATP production?

A

Can affect how proteins involved in oxidative phosphorylation + Krebs cycle function - reducing ATP production

56
Q

How can mitochondrial diease increase the rate of anaerobic respiration?

A

In order to make up some of the ATP shortage. Resulting in lots of lactate being produced.

57
Q

What effects can lots of lactate have?

A

Muscle fatigue and weakness, some lactate can diffuse in the bloodstream leading to high lactate concentration in blood.

58
Q

What process is used to move pyruvate into the mitochondrial matrix?

A

Active Transport

59
Q

Name the stage of aerobic respiration that produces reduced coenzymes, but no ATP

A

The Link Reaction

60
Q

What happens in anaerobic respiration of animal cells?

A

The pyruvate produced in glycolysis is converted into lactate in order to regenerate NAD from reduced NAD. This allows glycolysis to continue as it requires NAD to convert TP into pyruvate.

61
Q

Investigating the factors affecting respiration in single-celled organisms…

A

yeast - are single celled organisms which can be grown in a culture w/ plenty of oxygen and anaerbically w/ no oxygen.

62
Q

What is a manometer?

A

A capillary tube filled with coloured fluid - with a calibrated scale.

63
Q

A student is measuring the rate of respiration in woodlice in a manometer. Suggest a suitable control.

A

A test tube set up the same way as the test tube containing the woodlice, but containing an equivalent amount of glass beads instead of woodlice.

64
Q

What gas is being collected in the gas syringe - when measuring the rate of aerobic respiration in a yeast culture?

A

Carbon dioxide

65
Q

What does required practical 9 investigate? (respiration practical)

A

The effect of temperature on both aerobic and anaerobic respiration in yeast.

66
Q
  1. Required Practical 9
A

Put known vol + conc of substrate solution (e.g. glucose) in test tube.
Add known volume of buffer solution - keep pH constant.
CHOOSE OPTIMUM pH for yeast you’re using.

67
Q
  1. Required Practical 9
A

Place test tube in water bath set to one of the temps being investigated. Leave for 10 mins - allows temp of substrate to stabilise

68
Q
  1. Required Practical 9
A

Add known vol of yeast suspension to test tube - stir for 2 mins

69
Q
  1. Required Practical 9
A

Add known vol of methylene blue to test tube + seal tube w/ bung

70
Q
  1. Required Practical 9
A

Shake test tube for set no. of secs (10s) + place back in water bath.
Start stopwatch immediately

71
Q
  1. Required Practical 9
A

Record how long it takes to change blue –> colourless.
Can use control to compare colours

72
Q
  1. Required Practical 9
A

Repeat steps 1-6 for each temp - calculate a mean time for the colour change to occur at each temp.

73
Q
  1. Required Practical 9
A

Calculate mean rate of respiration of yeast at each temp - use equation:
Mean rate of respiration = 1 / mean time for colour change to occur

AQA A Level Biology (19 decks)

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