Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OCR A level Biology HJ > Respiration > Flashcards

Respiration Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

where do most reactions in respiration take place?

A

mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

draw and label a diagram of mitochondria

A

insert pic page 482 KERBOODLE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is a coenzyme?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the coenzymes used in respiration?

A

NAD, , coenzyme and FAD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what do NAD, coenzyme A and FAD do?

A

NAD and FAD transfer hydrogen form one molecule to another.

This means they can reduce (give hydrogen to) or oxidise (take hydrogen from) a molecule)

Coenzyme A transfers acetate between molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the 4 stages of respiration?

A

1- Glycolysis
2-the link reaction
3-the Krebs cycle
4-Oxidative phosphorylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

where does the 1st stage of respiration take place?

A

Glycolysis happens in the cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

where do stage 2,3 and 4 of respiration take place?

A

2-the link reaction
3-the krebs cycle
4-Oxidative phosphorylation
take place in the mitochondira

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what other complex organic molecules can organisms break down to respire?

A

fatty acids, amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what product does glycolysis make from glucose?

A

pyruvate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what happens in glycolysis?

A

-glycolysis involves splitting one molecule of glucose (with 6C) into 2 smaller molecules of pyruvate (3C)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

is glycolysis involved in aerobic or anaerobic respiration ?

A

glycolysis is the first stage of both aerobic and anaerobic respiration and doesn’t need oxygen to take place- so it’s anaerobic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what + describe are the 2 stages of glycolysis?

A

1-phosphorylation:
=ATP is used to phosphorylate glucose to triose phosphate.
-phosphorylation is the process of adding phosphate to a molecule

2-oxidation:
=then triose phosphate is oxidised releasing ATP

-overall there’s a net gain of 2 ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are the 4 main steps in glycolysis?

A

1-phosphorylation;
-2 molecules of ATP release 2 phosphates and attach onto a glucose molecule forming hexose bisphosphate

2- lysis:
-this destabilises the molecule causing it to split into 2 triose phosphate molecules

3-phosphrylation:
-another phosphate group is added onto the each triose phosphate forming triose bisphosphate molecules. These phosphate groups come from free inorganic phosphate (Pi) floating in the cytoplasm.

4-dehydrogenation and formation of ATP:
-the 2 triose bisphosphate molecules are then oxidised by the removal of hydrogen atoms (dehydrogenation) to form 2 pyruvate molecules.
|
|
NAD coenzymes accept the removed hydrogen- they are reduced, forming 2 reduced NAD molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

draw a diagram showing a summary of what happens in glycolysis

A

insert pic page 481 KERBOODLE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the products of glycolysis and where do the go?

A
  • 2 reduced NAD = to oxidative phosphorylation
  • 2 pyruvate = to the link reaction
  • 2 ATP (net gain) = used for energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what happens in the link reaction?

A
  • pyruvate is actively transported into the matrix of the mitochondria by specific carrier proteins
  • here the link reaction converts pyruvate to acetyl Coenzyme A
  • pyruvate is decarboxylated, so one carbon atom is removed from pyruvate in the form of CO2.
  • NAD is reduced to NADH- it collects hydrogen from pyruvate, changing pyruvate, changing pyruvate into acetate.
  • Acetate is combined with coenzyme A (CoA_ to from acetyl coenzyme A (CoA).
  • no ATP is produced in this reaction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the first stage of aerobic respiration ?

A

oxidative decarboxylation(link reaction)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

why is it called the ‘link’ reaction?

A

because it is the step that links anaerobic glycolysis, occurring in the cytoplasm, to the aerobic steps of respiration, occurring in the mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how many pyruvate molecules are made for every glucose molecules that enters glycolysis?
what does this mean?

A

2

-this means the link reaction and the 3rd stage (the Krebs cycle) happens twice fro every glucose molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what are the products of 2 link reactions and where do they go?

A

2 acetyl coenzyme A=> to the Krebs cycle
2 CO2=> released as a waste product
2 reduced NAD=> to oxidative phosphorylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what does the Krebs cycle produce?

A

reduced FAD–oxidative phosphorylation
reduced NAD x3–oxidative phosphorylation
CO2 x2–waste
ATP x1–used for energy
CoA–reused in link reaction
oxaloacetate–regenerated to be used again in kreb cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what reactions does the Krebs cycle involve?

A

oxidation- reduction reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

where does the Krebs take place?

A

in the matrix of the mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

how many times does the Krebs cycle take place for every pyruvate molecule?

A

the cycle happens once for every pyruvate molecule, so it goes round twice for every glucose molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

draw and label a diagram for one turn of the Krebs cycle

A

insert pic page 415 CGP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what are the 3 stages of the Krebs cycle?

A

1-formation of citrate
2-formation of a 5-carbon compound
3-regenerate of oxaloacetate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what happens at the 1st stage of the Krebs cycle?

A

1-FORMATION OF CITRATE:
-the acetyl group from acetyl CoA (produced in the link reaction) combines with oxaloacetate to form citrate (citric acid).
-This is catalysed by citrate synthase.
-Coenzyme A goes back to the link reaction reaction to be used again.
CoA
—–^
oxaloacetate (4C) + acetyl CoA (2C)———–> citrate (6C)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what happens at the 2nd stage of the Krebs cycle?

A

2-FORMATION OF A 5-CARBON COMPOUND:

  • the 6C citrate molecule is converted to a 5C molecule.
  • decarboxylation occurs, where carbon dioxide is removed.-dehydration also occurs.
  • the hydrogen is used to produce reduced NAD and NAD
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what happens at the 3rd stage of the Krebs cycle?

A

3-REGENERATION OF OCALOACETATE:

  • the 5C molecule is then converted to a 4C molecule.
  • (there are some intermediate compounds formed during this conversion)
  • decarboxylation and dehydrogenation occur, producing 1 molecule of reduced FAD and 2 of reduced NAD.
  • ATP is produced by the direct transfer of a phosphate group from an intermediate compound to ADP.
  • citrate has now been converted into oxaloacetate.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is meant by substrate- level phosphorylation?

A

when a phosphate group is directly transferred from one molecule to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what are the products from one Krebs cycle and do they each go?

A

1 coenzyme A=> reused in the next link reaction
Oxaloacetate=>regeneration for use in the next Krebs cycle
2 CO2=> released as a waste product
1 ATP=>used for energy
3 reduced NAD=>to oxidative phosphorylation
1 reduced FAD=>to oxidative phosphorylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what is the process of oxidative phosphorylation?

A

oxidative phosphorylation is the process where the energy carried by electrons, from reduced coenzymes (reduced NAD and reduced FAD), is used to make ATP.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

draw and label a diagram showing the 7 stages of oxidative phosphorylation

A

insert pic page 417 CGP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what are the 7 stages of oxidative phosphorylation?

A

1- hydrogen atoms are released from reduced NAD and reduced FAD as they’re oxidised to NAD and FAD. The hydrogen atoms spilt into protons (H+) and (e-).

2-the electrons move along the electron transport chain (made up of 3 electron carriers), losing energy a each carrier. The electron transport chain located in the inner mitochondrial membrane. This membrane is folded into cristae, which increases the membrane’s surface area to maximise respiration.

3-this energy is used by the electron carriers to pump protons from the mitochondrial matrix into the intermembrane space (the space between the inner and outer mitochondrial membranes).

4-the concentration of protons is now higher in the intermembrane space than in the mitochondrial matrix- this forms an electrochemical gradient (a concentration gradient of ions).

5-protons move down the electrochemical gradient, back into the mitochondrial matrix, via ATP synthase.

6-This movement drives the synthesis of ATP from ADP and inorganic phosphate (Pi). This process of ATP production driven by the movement of H+ ions across a membrane (due to electrons moving down an electron transport chain) is called chemiosmosis (which is described by the chemiosmosis theory).

7-in the mitochondrial matrix, at the end of the transport chain, the protons, electrons and oxygen (from the blood) combine to form water. Oxygen is said to be the final electron acceptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

draw a diagram showing how electrons lose energy as they move along the electron transport chain

A

insert pic page 417 CGP bottom right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what is role of electron carriers?

A
  • the job of a carrier is to transfer electrons

- when a carrier receives electrons it’s reduced and when it passes on electrons it becomes oxidised again.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

draw a diagram summarising all the stages of aerobic respiration

A

insert pic page 418 CGP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

summarise what happens in oxidative phosphorylation?

A

oxidative phosphorylation makes ATP using energy from the reduced coenzymes- 2.5 ATP are made from each reduced NAD and 1.5 ATP are made from each reduced FAD

40
Q

draw a table showing how a cell can make 32 ATP from one molecule of glucose in aerobic respiration.

(remember, 1 molecule of glucose produces 2 pyruvate, so the link reaction and Krebs cycle happen twice)

A

Stage of | Molecules produced | Number of ATP
respiration | | molecules
_____________________________________________
Glycolysis | 2 ATP | 2
Glycolysis | 2 reduced NAD | 2 x 2.5 = 5
Link reactionX2| 2 reduced NAD | 2 x 2.5 = 5
Krebs cycle X2 | 2 ATP | 2
Krebs cycle X2 | 6 reduced NAD | 6 x 2.5 = 15
Krebs cycle X2 | 2 reduced FAD | 2 x 1.5 = 3
________________
Total ATP = 32

41
Q

what is the difference between aerobic and anaerobic respiration?

A

anaerobic respiration is a type of respiration that doesn’t use oxygen.

  • like aerobic respiration, it starts with glycolysis
  • unlike aerobic respiration it doesn’t involve the link reaction, the Krebs cycle or oxidative phosphorylation
42
Q

what are the 2 types of anaerobic respiration?

A

alcoholic fermentation and lactate fermentation

43
Q

what are the similarities between alcoholic fermentation and lactate fermentation?

A
  • they both take place in the cytoplasm
  • they both produce 2 ATP per molecule of glucose
  • they both start with glycolysis (which produces pyruvate)
44
Q

how do alcoholic fermentation and lactate fermentation differ?

A
  • they differ in which organisms they occur in and what happens to the pyruvate.
  • lactate fermentation occurs in mammals and produces lactate.
45
Q

what happens in the process of lactate fermentation?

A

1-reduced NAD (from glycolysis) transfers hydrogen to pyruvate to form lactate an NAD.
2-NAD can then be reused in glycolysis.
3-the production of lactate regenerates NAD.
4-Glycolysis needs NAD in order to take place.

46
Q

what is the benefit of lactate fermentation?

A

This means glycolysis can continue even when there isn’t much oxygen around, so a small amount of ATP can still be produced to keep some biological processes going.

47
Q

describe our cells tolerance level to lactate

A
  • our cells can tolerate a high level of lactate (and the coinciding low pH conditions) for short periods of time.
  • e.g. during short periods of hard exercise, when they can’t get enough ATP from aerobic respiration.
  • However, too much lactate is toxic and is removed form the cells into the bloodstream.
  • The liver takes up lactate from the bloodstream and converts it back into glucose in a process called gluconeogenesis.
48
Q

define gluconeogenesis

A

-The liver takes up lactate from the bloodstream and converts it back into glucose in a process called gluconeogenesis.

49
Q

describe the process of alcoholic fermentation and its benefit

A
  • CO2 is removed from pyruvate to form ethanal.
  • reduced NAD (from glycolysis) transfers hydrogen to ethanal to form ethanol and NAD.
  • NAD can then be reused in glycolysis.
  • the production of ethanol also regenerates NAD so glycolysis can continue when there isn’t much oxygen around.
50
Q

other than yeast cells, where else does alcoholic fermentation occur?

A

in plants

51
Q

what is a disadvantage of anaerobic respiration?

A

the ATP yield from anaerobic respiration is always lower than from aerobic respiration

52
Q

why is the yield of ATP lower in anaerobic respiration?

A

This is because anaerobic respiration only includes one energy- releasing stage (glycolysis), which only produces 2 ATP per glucose molecule.
WHEREAS AEROBIC RESPIRATION PRODUCES 32 ATP PER MOLECULE OF GLUCOSE.

-The energy- releasing reactions of the Krebs cycle and oxidative phosphorylation needs oxygen, so they can’t occur during anaerobic respiration.

53
Q

what is meant by a respiratory substrate?

-give examples

A

any biological molecule that can be broken down in respiration to release energy
-cells respire glucose, but they also respire other carbohydrates, lipids and proteins- these are all respiratory substrates.

54
Q

at what stage do the different respiratory substrates (glucose, proteins and lipids) enter respiration?

A
  • glucose enters right at the beginning- at the start of glycolysis.
  • proteins and lipids enter respiration at the Krebs cycle.
55
Q

why do different respiratory substrates have different energy values?
____________________________________________
Respiratory substrates | Average energy value (kJ g-1)
carbohydrates | 15.8
lipids | 39.4
proteins | 17.0

A
  • lipids have the highest energy value, followed by proteins, then carbohydrates.
  • this is because most ATP is made in oxidative phosphorylation, which requires hydrogen atoms form reduced NAD and reduced FAD.
  • this means that respiratory substrates that contains more hydrogen atoms per unit of mass cause more ATP to be produced when respired.
  • Lipids contain the most hydrogen atoms per unit of mass, followed by proteins and then carbohydrates
56
Q

what is the formula for respiratory quotients?

A

RQ= volume or molecules of CO2 released
_______________________________
volume or molecules of O2 consumed

57
Q

what are the respiratory quotients for lipids (triglycerides), proteins or amino acids and carbohydrates?

A

.lipids (triglycerides) = 0.7
proteins or amino acids = 0.9
carbohydrates = 1

58
Q

why do lipids (triglycerides), proteins or amino acids and carbohydrates have the respiratory quotients that they do?

A

lipids and proteins have an RQ value lower than 1 because more oxygen is needed to oxidise fats and lipids than to oxidise carbohydrates

59
Q

what are the different types of respiratory quotients that can be calculated?

A
  • you can work out the respiratory quotient for a whole organism as well as a particular substrate.
  • the respiratory quotient for a whole organism is an average of all of the respiratory quotients for all the different molecules the organism is respiring
60
Q

why is the respiratory quotient for an organism useful?

A

-because it tells you what kind of respiratory substrate an organism is respiring and what type of respiration it’s using (aerobic or anaerobic)

61
Q

what is the RQ for humans under normal conditions and why?

A
  • under normal conditions the usual RQ for humans is between 0.7 and 1.0.
  • An RQ in this range shows that some fats (lipids) are being used for respiration, as well as carbohydrates like glucose.
  • Protein isn’t normally used by the body for respiration unless there’s nothing else.
62
Q

what is meant by a high RQ for humans and what does it mean?

A

High RQs (greater than 1) man that an organism is short of oxygen, and is having to respire anaerobically as well as aerobically.

63
Q

why do plants sometimes have a low RQ?

A

this is because the CO2 released in respiration is used for photosynthesis (so it’s not measured).

64
Q

what is the RQ of Oleic acid and why?

A

Oleic acid is a fatty acid.
Fatty acids make up triglycerides (lipids), so you would expect oleic acid to have an RQ of about 0.7.
Like other lipids, oleic acids enters respiration at the Krebs cycle.

65
Q

why does the rate of CO2 production give an indication of the yeast’s respiration rate?

A
  • yeast are single-celled organisms that can be grown in culture.
  • they can respire aerobically when plenty of oxygen is available and anaerobically when oxygen isn’t available.
  • both aerobic and anaerobic respiration in yeast produce CO2.
  • So the rate of CO2 production gives an indication of the yeast’s respiration rate.
66
Q

describe the method on one way to measure CO2 production using a gas syringe to collect CO2?
(10 steps)
AEROBIC RESPIRATION

A

1-put a known volume and concentration of substrate solution (e.g. glucose) in a test tube.

2-add a known volume of buffer solution to keep the pH constant (choose the optimum pH for the yeast you’e testing- usually 4-6).

3-place the test tube in a water bath set to 25 degrees. This ensures that the temperature stays constant throughout the experiment. Leave it there for about 10 minutes to allow the temperature of the substrate to stabilise.

4-add a known mass of dried yeast (e.g. Saccharomyces cerevisiae) to the test tube and stir for 2 minutes.

5-after the yeast has dissolved into the solution, put a bung with a tube attached to a gas syringe in the top of the test tube. The gas syringe should be set to zero.

6-start a stop watch as soon as the bung has been put in the test tube.

7-as the yeast respire, the CO2 formed will travel up the tube and into the gas syringe, which is used to measure the volume of CO2 released.

8-at regular time intervals (e.g. every minute), record the volume of CO2 tat is present in the gas syringe. Do this for a set amount of time (e.g. 10 minutes).

9-a control experiment should also be set up, where no yeast is present. No CO2 should be formed without the yeast.

10-repeat the experiment three times. Use your data to calculate the mean rate of CO2 production.

67
Q

Draw a diagram showing how apparatus can be set up measure aerobic respiration in yeast.

A

insert pic page 424 CGP bottom

68
Q

describe the method on one way to measure CO2 production using a gas syringe to collect CO2?
(11 steps)
ANAEROBIC RESPIRATION

A

1-put a known volume and concentration of substrate solution (e.g. glucose) in a test tube.

2-add a known volume of buffer solution to keep the pH constant (choose the optimum pH for the yeast you’e testing- usually 4-6).

3-place the test tube in a water bath set to 25 degrees. This ensures that the temperature stays constant throughout the experiment. Leave it there for about 10 minutes to allow the temperature of the substrate to stabilise.

4-add a known mass of dried yeast (e.g. Saccharomyces cerevisiae) to the test tube and stir for 2 minutes.

5-after the yeast has dissolved into the substrate solution, trickle some liquid paraffin down the inside of the test tube so that it settles on and completely covers the solution. this will stop oxygen getting in, which will force the yeast to respire anaerobically.

6-put a bung, with a tube attached to a gas syringe, in the top of the test tube. The gas syringe should be set to 0.

7-start a stop watch as soon as the bung has been put in the test tube.

8-as the yeast respire, the CO2 formed will travel up the tube and into the gas syringe, which is used to measure the volume of CO2 released.

9-at regular time intervals (e.g. every minute), record the volume of CO2 tat is present in the gas syringe. Do this for a set amount of time (e.g. 10 minutes).

10-a control experiment should also be set up, where no yeast is present. No CO2 should be formed without the yeast.

11-repeat the experiment three times. Use your data to calculate the mean rate of CO2 production.

69
Q

why are you able to compare the results for both experiments (aerobic and anaerobic respiration)?

A

-the only difference between these experiments is the presence or absence of oxygen, so you can directly compare your results for both experiments with each other to find out how the respiration rate of yeast under aerobic and anaerobic conditions differ.

70
Q

what else can you measure using the methods for aerobic and anaerobic respiration?

A

-you can also easily adapt these methods to investigate the effects of variables, such as temperature, substrate concentration and the due of different respiratory substrates (e.g. sucrose), on the respiration rate.

71
Q

how can you test that the gas produced, in the experiments for aerobic and anaerobic respiration, is definitely CO2?

A

connect the yeast and substrate solution to a test tube of limewater rather than a gas syringe. The limewater will turn cloudy in the presence of CO2.

72
Q

what are respirometers?

A

respirometers ca be used to indicate the rate of aerobic respiration by measuring the amount of oxygen consumed by an organism over a period of time.

73
Q

describe a Method that can be used to measure the respiration rate of other small organisms or of plant seeds

A

1-the syringe is then used to set the fluid to a known level

2- the apparatus is then left for a set period of time (e.g. 20 mins). During that time, there’ll be a decrease in the volume of air in the test tube, due to oxygen consumption by the woodlice (all the CO2 produced is absorbed by the potassium hydroxide). The decrease in the volume of air will reduce the pressure in the tube and cause the coloured liquid in the manometer to move towards the test tube.

3-the distance moved by the liquid in a given time is measured. This value can then be used to calculate the volume of oxygen taken in by the woodlice per minute. (you also need to know the diameter of the capillary tube in the manometer to do this.)

4-any variables that could affect the results are controlled and kept the same (e.g. volume of potassium hydroxide and mass of woodlice.

74
Q

draw a diagram showing how a respirometer can be set up to measure oxygen consumption.

A

insert pic page 426 CGP CGP

75
Q

how can we analyse data and draw conclusions from our experiment using a respirometer to measure oxygen consumption?

A
  • respirometers cab be set up with an electronic oxygen sensor to measure the oxygen concentration inside the respirometer chamber at set intervals and also with data loggers to automatically record the data measured by the sensor.
  • Using technology like this reduces the chance of human error when it comes to recording data.
  • The data collected by the data logger can be put into data analysis software, which can help you to analyse you data and draw conclusions from your experiment.
76
Q

what are some limitation of the experiment ‘using respirometer to measure oxygen consumption’?

A

-it can very difficult to accurately read the meniscus of the fluid in the manometer

77
Q

what are some safety precautions that should be taken when carrying out the experiment for ‘using respirometer to measure oxygen consumption’?

A

-wear eye protection when working with potassium hydroxide and make sure that the woodlice don’t come into contact with it.

78
Q

what are some ethical concerns when carrying out the experiment ‘using respirometer to measure oxygen consumption’?

A

-when using small organisms like woodlice, you must treat the woodlice with respect and ensure that they’re not harmed or distressed unnecessarily.

79
Q

where does the link reaction occur?

A

The link reaction occurs in the mitochondrial matrix.

80
Q

what reactions does the link reaction involve?

A

It involves the decarboxylation and dehydrogenation of pyruvate into acetyl CoA, catalysed by the multi-enzyme complex pyruvate dehydrogenase. No ATP is produced in this reaction.

81
Q

what are the 3 stages of the link reaction?

A
  1. 3-carbon pyruvate is oxidised to an acetyl group (2-carbon acetate) through dehydrogenation and decarboxylation. A carboxyl group is lost in the process to form a carbon dioxide molecule
  2. The lost hydrogens are accepted by NAD to form reduced NAD (NADH), which is used later in respiration to produce ATP
  3. The acetyl group combines with coenzyme A (CoA) to produce the compound acetyl CoA
82
Q

what is the equation for the link reaction?

A

2 pyruvate + 2NAD + 2CoA ——> 2Co2+ 2 reduced NAD + 2 acetyl CoA

83
Q

what are the 3 stages of the Krebs cycle?

A

1-Actetyl CoA delivers an acetyl group to the Krebs cycle. The 2(C) acetyl group combines with 4(C) oxaloacetate to form 6(C) citrate.

2-the citrate molecule undergoes decarboxylation and dehydrogenation producing one reduced NAD and CO2. A 5(C) compound is formed.

3-the 5(C) compound undergoes further decarboxylation and dehydrogenation reactions, eventually regenerating oxaloacetate, and so the cycle continues. More CO2, 2 more reduced NADs, and one reduced FAD are produced. ATP is also produced by substrate-level phosphorylation.

84
Q

what are the differences between the coenzymes NAD and FAD?

A
  • NAD takes part in all stages of cellular respiration but FAD only accepts hydrogen in the Krebs cycle
  • NAD accepts one hydrogen and FAD accepts 2 hydrogen
  • reduced NAD is oxidised at the start of the start of the electron transport chain releasing protons and electrons while reduced FAD is oxidised further along the chain.
  • reduced NAD results in the synthesis of 3 ATP molecules but reduced FAD results on the synthesis of only 2 ATP molecules
85
Q

what are a number of ways that NAD can be represented and why?

A

NADH
NADH + H+
NADH2+
the reason for this is that NAD is actually charged sp so more accurately charged so is more accurately represented as NAD+.
-when NAD+ is reduced it accepts 2 protons and an electron pair (from a C-H bond) forming NADH + H+.
NADH, or reduced NAD, then transfers the proton and electron pair to a subsequent reaction.

86
Q

what is the need for cellular respiration?

A

The energy released during respiration is used to synthesise molecules of ATP, which is used an immediate source of energy.
Respiration also produces heat energy, helping multi-cellular organisms to coordinate key processes such as maintaining a suitable body temperature.

87
Q

what are the 2 different types of metabolic reactions and their features?

A

anabolic ans catabolic reactions

-Anabolic Reactions
• Involve synthesising large molecules from smaller molecules
• Requires energy
• For example, building a protein from amino acids

-Catabolic Reactions
• Involve breaking down large molecules to form smaller molecules
• Releases energy
• For example, digestion and breakdown of proteins into its amino acids

88
Q

whats the function of outer mitochondrial membranes and its adaptations that enable them to perform their function in respiration?

A

The outer mitochondrial membrane contains protein channels and carriers, which allows the passage of molecules, needed in respiration, into the mitochondria such as pyruvate

89
Q

whats the function of inner mitochondrial membranes and its adaptations that enable them to perform their function in respiration?

A

The inner mitochondrial membrane is the site at which ATP synthesis takes place.ATP synthesis requires a large positive proton gradient to exist across the inner mitochondrial membrane. This can be maintained as the inner mitochondrial membrane is much less permeable to protons than the outer membrane

90
Q

whats the function of cristae and its adaptations that enable them to perform their function in respiration?

A

The cristae provide a large surface area to embed necessary proteins (e.g. the electron carriers)and enzymes (e.g. ATP synthase)needed for aerobic respiration to occur.

-Cristae:
Highly-folded inner mitochondrial membrane.

91
Q

whats the function of mitochondrial matrix and its adaptations that enable them to perform their function in respiration?

A

The matrix contains mitochondrial DNA and ribosomes, allowing most enzymes required in respiration to be synthesised in the mitochondria itself. Specifically, it allows for the link reaction and Krebs cycle to take place as it contains:

  • Specific enzymes — catalyse certain stages in these reactions
  • Oxaloacetate — 4-carbon compound in the Krebs cycle that accepts the acetyl group produced in the link reaction
  • NAD and FAD molecules
  • Mitochondrial Matrix:
  • Inner part of a mitochondrion that is fluid-filled.
92
Q

​

​
what is the formula for standard deviation?

A 
|-------------
          |        _
  S  =  | ∑ (x-x  )^2
          |---------------
        \​ |      n-1
∑= sum of 
x= value in the data set
-
x (x with a line on top)= mean
n=number of values
S= standard deviation
93
Q

after completing the practical experiments how can you compare the means of data values of 2 sets of data?

A

use standard deviation to measure the spread of data and/ or Student’s t- test to compare means of data values

94
Q

whats the formula for student t-test?

A 
-      -                               
                x1  - x2
t= --------------------------------------
     -----------------------------------
   \| (S1 ^2 / n1) + (S2 ^2 / n2) 
-
x (x with line above) = mean
s = standard deviation
n = number of values of data set
1 or 2 = data set being referred to
95
Q

what needs to be ensured for the experiment for anaerobic respiration?

A

that the flask is sealed

96
Q

how do we measure the rate of respiration?

A

1- as the yeast respires CO2 is released increasing the volume of gas in the flask

2-as the volume of gas in the tube increases the pressure will increase causing the coloured liquid to move along the capillary tube.

3-the distance moved by the liquid together with diameter of the tube can be used to calculate the increase in volume of gas (CO2) in the flask over a certain period of time.

4-this is a measure of the rate of respiration

97
Q

how can a student use a data logger?

A

1- the student placed a solution containing yeast and glucose in the flask and inserted a CO2 sensor.

2-Th solution was covered with a layer of liquid paraffin.

3-the software was set up to record readings every 50 seconds fro 1600 seconds.

4-the readings are displayed in graphical form

OCR A level Biology HJ (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions