Respiration

Question 1

Prior Knowledge
– Respiration is an enzyme _________process.
– Aerobic respiration is mainly carried out within the _____________.
– During ___________respiration, glucose and oxygen react to produce carbon dioxide and water. Energy is released in this process.
– The energy released during respiration is used to ___________ larger molecules, contract muscles (in animals), maintain a constant body ______________(birds and mammals) and produce ________ acids (in plants).
– ____________respiration releases less energy and is used when insufficient _______reaches the muscles.
– Glucose is not completely broken down and produces lactic acid. This causes muscle fatigue. An oxygen debt has to be repaid in order to oxidise the lactic acid into glucose and water.

Answer 1

– Respiration is an enzyme catalysed process.
– Aerobic respiration is mainly carried out within the mitochondria.
– During aerobic respiration, glucose and oxygen react to produce carbon dioxide and water. Energy is released in this process.
– The energy released during respiration is used to synthesise larger molecules, contract muscles (in animals), maintain a constant body temperature (birds and mammals) and produce amino acids (in plants).
– Anaerobic respiration releases less energy and is used when insufficient oxygen reaches the muscles.
– Glucose is not completely broken down and produces lactic acid. This causes muscle fatigue. An oxygen debt has to be repaid in order to oxidise the lactic acid into glucose and water.

Question 2

Mitochondrion Adaptations -
Inner membrane folded to give large surface area.
Matrix containing many enzymes.
Double membrane with intermembrane space
Contains own DNA and ribosomes

so…?

Answer 2

So many electron carriers and enzymes such as ATP synthase can be housed
So Reactions of link reaction and Krebs cycle can proceed fast enough
So different reactions can be compartmentalized – this allows control.
SO able to produce own proteins in translation - enzymes and transport proteins

Question 3

Can you remember what a coenzyme is?

Answer 3

A coenzyme is a molecule that aids the function of an enzyme. It does this by transferring a chemical group from one molecule to another. Co-enzymes used in respiration include NAD, coenzyme A and FAD

Question 4

What is
An oxidation reaction?
A reduction reaction?
A phosphorylation reaction?
A decarboxylation reaction?

Answer 4

An oxidation reaction is the loss of hydrogen or electrons, or the gain of oxygen.
A reduction reaction is the gain of hydrogen or electrons, or the gain of hydrogen.
A phosphorylation reaction is the transfer of a phosphate group.
A decarboxylation reaction is the removal of carbon dioxide.

Question 5

Complete the table to show the major differences between aerobic and anaerobic respiration

Answer 5

Question 6

There are 4 stages in aerobic respiration

Answer 6

Glycolysis
The link reaction
The Krebs cycle
Oxidative phosphorylation

Question 7

Glycolysis takes place in the (a)
Glycolysis makes two molecules of (b)
If (C) is available then the pyruvate crosses the (D)membrane. The other 3 stages occur in the mitochondria
If oxygen is absent then anaerobic respiration occurs in the (E).

Answer 7

a. cytoplasm
b. pyruvate(each 3C) from 1 molecule of
glucose (6C)
c. oxygen
d. mitochondrial
e. cytoplasm

Question 8

There are 2 stages in glycolysis
1. Phosphorylation

Answer 8

Glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP. This creates 2 molecules of TP and 2 ADP

Question 9

There are 2 stages in glycolysis
2. Oxidation

Answer 9

TP is oxidised forming 2 molecules of pyruvate. NAD is reduced, forming 2NADH.
4ATP are produced
Overall gain = 2 ATP

Question 10

Exam Tips

Answer 10

Glycolysis takes place in the cytoplasm because glucose cannot cross the outer mitochondrial membrane. Pyruvate can cross this membrane so the rest of the reactions occur within the mitochondria.

For each molecule of glucose at the start of the process, 2 molecules of TP are produced. Each molecule of TP goes on to form a molecule of pyruvate

Question 11

Products from glycolysis
1. 2 Reduced NAD
2. 2 pyruvate
3. 2 ATP

Answer 11

1.To oxidative phosphorylation
2.Actively transported into the mitochondrial matrix for use in the link reaction
3.Used for energy

Question 12

Q1. What is the name of substance:
a) V? b) W? c) X? d) Y? e) Z?
Q2. What is the name of process
A b) B?
Q3 What part of the process is missing off the diagram above?
Q4. If 5 molecules of glucose enter the process of glycolysis:
a) How many molecules of pyruvate will be produced?
b) How many molecules of reduced NAD will be produced?
c) What will the net gain of ATP be?

Answer 12

Q1. What is the name of substance:
a) V?ATP b) W? REDUCED NAD c) X? Pi d) Y? TP e) Z?H+ ions
Q2. What is the name of process
A Phosphorylation b) B? oxidation
Q3 What part of the process is missing off the diagram above?
Formation of 4 x ATP from ADP and Pi between Y and pyruvate
Q4. If 5 molecules of glucose enter the process of glycolysis:
a) How many molecules of pyruvate will be produced?10 (5x2)
b) How many molecules of reduced NAD will be produced?10
c) What will the net gain of ATP be?10 (4x ATP are made per glucose but two are used in phosphorylation so net gain is 2…so 5x2)

Question 13

What happens in the Link reaction
1.
2.
3.

Answer 13

1. Pyruvate is decarboxylated (carbon dioxide is removed)
2. NAD is reduced- it collects hydrogen from pyruvate. Pyruvate is converted into acetate
3. The acetate combines with coenzyme A to form acetyl coenzyme A (acetyl-coA)

No ATP is produced

Question 14

Anaerobic Respiration
There is no oxygen and therefore the process stops at _______________

In plants and yeast ________is produced. In animals __________is produced. The production of both regenerates ____. This means __________can continue even when ________is in short supply. Therefore small amounts of ____are produced keeping biological processes going

Answer 14

GLYCOLYSIS

In plants and yeast Ethanol is produced. In animals Lactate is produced. The production of both regenerates NAD. This means glycolysis can continue even when oxygen is in short supply. Therefore small amounts of ATP are produced keeping biological processes going

Question 15

Alcoholic Fermentation

The reduction of _________to _________is essential to regenerate the coenzyme ___. It can then return to _____________ and ensure a net 2 ATP are produced

Occurs in _______and _______

Answer 15

The reduction of ethanal to ethanol is essential to regenerate the coenzyme NAD. NAD can then return to glycolysis and ensure a net 2 ATP are produced

Occurs in plants and yeast

Question 16

Lactate Formation

Answer 16

The conversion of pyruvate into lactic acid is reversible – how would you show this in the diagram?
Lactic acid fermentation takes place in skeletal muscle alongside aerobic respiration all the time. This allows for greater intensity (anaerobic) and duration (aerobic) activity.
Lactic acid dissociates to form Lactate and Hydrogen ions (H+) - what problem could this cause in muscle?

Question 17

Hexokinase is an enzyme that catalyses the production of glucose phosphate.
Suggest and explain how hexokinase is involved in glycolysis.
Suggest a benefit of hexokinase being inhibited by the product of this reaction

Answer 17

1a) It catalyses the phosphorylation of glucose to glucose phosphate using phosphate from ATP.
b) It may help to stop the over production of glucose phosphate

Question 18

What is the name of substance:
X? ii) Y? iii) Z?
B Which process A or B:
i) Is lactate fermentation? ii) Happens in plant cells iii) can happen in bacterial cells?

Answer 18

2ai) Lactate/lactic acid
ii) Pyruvate iii) ethanol
3. A ii) B iii) A

Question 19

PPQ

Answer 19

Question 20

What is ATP used for in glycolysis?

Answer 20

It is used to phosphorylate the glucose (1)

Question 21

What role does the coenzyme NAD play in glycolysis?

Answer 21

It is used in the oxidation of triose phosphate to pyruvate. NAD collects the hydrogen ions from triose phosphate , forming reduced NAD (2)

Question 22

If 5 molecules of glucose enter the process of glycolysis, how many molecules of pyruvate will be produced?

Answer 22

Two molecules of pyruvate are made from every glucose molecule that enters glycolysis (2)

Question 23

During fermentation, reduced NAD is oxidised to NAD.
What happens to the oxidised NAD?

Answer 23

It is used in glycolysis. It collects hydrogen ions from triose phosphate in the production of pyruvate. (2)

Question 24

. What is the final product of anaerobic respiration by animal cells?

Answer 24

? Lactate/ lactic acid (1)

Question 25

The Link Reaction
How many carbon atoms in
Pyruvate
Acetyl coenzyme A
2. Name the 2 types of reaction which occur.
3. What can pyruvate do that glucose can’t?
4. What is the next stage of respiration?
5. Where does it take place?

Answer 25

1a) 3 b) 2
2. The pyruvate is decarboxylated and then oxidised (loses H)
Pyruvate can cross the mitochondrial membrane. Glucose can’t.
4. Kreb’s cycle
5. It occurs in the mitochondrial matrix

Question 26

Products of the link reaction
a) 2 acetyl coenzyme A
b) 2 carbon dioxide
c) 2 reduced NAD

Where do they go

Answer 26

Where it goes?
To the Krebs cycle
Released as a waste product
To oxidative phosphorylation

Question 27

Kreb’s cycle
This produces — and —. It involves a series of oxidation—-reactions and takes place in the —of the mitochondria. The cycle happens once for every — molecule.

Answer 27

Kreb’s cycle
This produces coenzymes and ATP. It involves a series of oxidation-reduction reactions and takes place in the matrix of the mitochondria. The cycle happens once for every pyruvate molecule.

Question 28

Kreb’s cycle

__________________(from the link reaction) joins with a 4C compound to form a __C compound. Coenzyme A goes back to the ______ __________
_____________occurs forming a __C compound. Dehydrogenation also occurs. The __________ is used to form _________________ from NAD
Decarboxylation and _____________ of the 5C compound occur to form a ___ C compound.
ATP is made by the removal of a ____________group. As the phosphate group is transferred directly from 1 molecule to another (ADP) we say the ATP has been formed by __________________phosphorylation.

Answer 28

`Acetyl coenzyme A (from the link reaction) joins with a 4C compound to form a 6C compound. Coenzyme A goes back to the link reaction
Decarboxylation occurs forming a 5C compound. Dehydrogenation also occurs. The hydrogen is used to form reduced NAD from NAD
Decarboxylation and dehydrogenation of the 5C compound occur to form a 4 C compound.
ATP is made by the removal of a phosphate group. As the phosphate group is transferred directly from 1 molecule to another (ADP) we say the ATP has been formed by substrate level phosphorylation.

Question 29

The products of Kreb’s cycle
Product from 1 Kreb’s cycle
a)1 coenzyme A
b)Oxaloacetate (4C)
c)2 carbon dioxide
d)1 ATP
e)3 reduced NAD
f)1 reduced FAD

Answer 29

Reused in the next link reaction
Regenerated for use in the next Kreb’s cycle
Released as a waste product
Used for energy
To oxidative phosphorylation
To oxidative phosphorylation

The table shows ONE turn of Kreb’s cycle
It turns TWICE for every glucose molecule

Question 30

Oxidative phosphorylation
The process where the energy carried by —, from reduced — (reduced —and reduced —) is used to make —.
Oxidative — involves the electron transport chain and —.

Answer 30

The process where the energy carried by electrons, from reduced coenzymes (reduced NAD and reduced FAD) is used to make ATP.
Oxidative phosphorylation involves the electron transport chain and chemiosmosis.

Question 31

Can you describe what is happening at each of the numbered steps?
Where does the oxygen come from…?

1. ___________ atoms are released from reduced NAD and reduced FAD. They are ___________to NAD and FAD, The hydrogen atoms split into __________ (H+) and electrons (e-)
2. The electrons move down the electron transport chain (made up of electron ___________) losing ___________ at each carrier.
3. The energy is used by the electron carriers to pump _________ from the mitochondrial ________ into the ____________ space.
4. The concentration of protons is now __________ in the intermembrane space than in the mitochondrial matrix- this forms an ___________gradient. (a concentration gradient of ions)
5. ___________then move down the electrochemical gradient, back across the ________ mitochondrial membrane and into the mitochondrial matrix, via ________________ (which is embedded in the mitochondrial membrane). This movement drives the synthesis of ATP from ____ and inorganic phosphate (Pi)
6. The process of ATP production driven by the movement of H+ ions ________ a membrane (due to electrons moving down an electron transport chain) is called ________________.
7. In the mitochondrial matrix, at the end of the transport chain, the protons, electrons and __________ (from the blood) combine to form water. Oxygen is said to be the ________ _____________ _______________.

Answer 31

Hydrogen atoms are released from reduced NAD and reduced FAD. They are oxidised to NAD and FAD, The hydrogen atoms split into protons (H+) and electrons (e-)
The electrons move down the electron transport chain (made up of electron carriers) losing energy at each carrier.
The energy is used by the electron carriers to pump protons from the mitochondrial matrix into the intermembrane space.
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)
Protons then move down the electrochemical gradient, back across the inner mitochondrial membrane and into the mitochondrial matrix, via ATP synthase (which is embedded in the mitochondrial membrane). This movement drives the synthesis of ATP from ADP and inorganic phosphate (Pi)
The 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.
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.

Question 32

As electrons move down the electron transport chain, they lose energy.
The job of the carrier is to transfer —–. When a carrier receives electrons it’s —–and when it passes on electrons it becomes —— again

Answer 32

The job of the carrier is to transfer electrons. When a carrier receives electrons it’s reduced and when it passes on electrons it becomes oxidised again

Question 33

Tip
Remember that —- involves a series of oxidation and reduction reactions.

Tip
Oxygen is the final electron
—

Tip
Questions may be about artificial — acceptors- these are —. This means that they can be used to model the function of e.g. NAD

Answer 33

Tip
Remember that respiration involves a series of oxidation and reduction reactions.

Tip
Oxygen is the final electron
acceptor

Tip
Questions may be about artificial hydrogen acceptors- these are reduced. This means that they can be used to model the function of e.g. NAD

Question 34

Answer 34

Question 35

Mitochondrial Diseases

Answer 35

ATP production can be affected by mitochondrial diseases. These affect how proteins involved in oxidative phosphorylation or the Kreb’s cycle function, reducing ATP production. This may cause anaerobic respiration to increase to try and make up the ATP shortage. Lots of lactate will be made, which can lead to muscle fatigue and weakness. Some lactate diffuses in to the blood resulting in a high concentration of lactate in the blood.