3.3.3 Respiration

Question 1

What do both aerobic and anaerobic respiration start with?

Answer 1

Glycolysis

Question 2

Where does glycolysis occur?

Answer 2

Happens in cytoplasm

Question 3

Is glycolysis are anaerobic or aerobic process?

Answer 3

Anaerobic process

Question 4

Name the 2 stages in glycolysis

Answer 4

1. Phosphorylation
2. Oxidation

Question 5

Glycolysis

Describe what happens in phosphorylation

Answer 5

1. Glucose is phosphorylated using phosphate from a molecule of ATP
   
   • Creates 1 molecule of glucose phosphate and 1 molecule of ADP
2. ATP is then used to add another phosphate = hexose bisphosphate
3. Hexose bisphosphate is splits into 2 molecules of TP

Question 6

Glycolysis

Describe what happens in oxidation

Answer 6

1. TP is oxidised (loses H) = 2 molecules of pyruvate
2. NAD collects H⁺ ions = 2 reduced NAD
3. 4 ATP produced, but 2 used up in stage 1 ∴ net gain of 2 ATP

Question 7

What happens to the products of glycolysis in aerobic respiration?

Answer 7

• 2 molecules of reduced NAD go to oxidative phosphorylation
• 2 pyruvate molecules are actively transported into matrix of mitochondria for link reaction

Question 8

Anaerobic Respiration

Pyruvate is converted into ___ in plants and yeast

Answer 8

Ethanol

(Using reduced NAD)

Question 9

Anaerobic Respiration

Pyruvate is converted into ___ in animal cells and some bacteria

Answer 9

Lactate

(Using reduced NAD)

Question 10

Illustrate Alcoholic Fermentation

(i.e. write equation)

Answer 10

Reduced NAD reduces/donate H ions to pyruvate to ethanol

Question 11

Illustrate Lactate Fermentation

Answer 11

Question 12

Name the 4 main stages in aerobic respiration

Answer 12

1. Glycolysis
2. Link Reaction
3. Krebs Cycle
4. Oxidative Phosphorylation

Question 13

Describe the link reaction

Answer 13

1. Pyruvate is decarboxylated
   
   • (1 C is removed in 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 (acetyl CoA)
4. No ATP produced

Question 14

2 pyruvate molecules are made for every glucose molecule that enters glycolysis. This means that the ____ _____ and _____ _____ happens _____ for every glucose molecule.

Answer 14

2 pyruvate molecules are made for every glucose molecule that enters glycolysis. This means that the link reaction and Krebs cycle happens twice for every glucose molecule.

Question 15

After Link Reaction

For each glucose molecule, state the quantity of each product and where they go

Answer 15

1. 2 molecules of acetyl CoA go into the Krebs cycle
2. 2 CO₂ molecules are released as waste product
3. 2 molecules of reduced NAD are formed and go to oxidative phosphorylation

Question 16

Krebs cycle Involves a series of ________ reactions

Answer 16

oxidation-reduction

Question 17

Where does the Krebs cycle takes place?

Answer 17

In matrix of mitochondria

Question 18

Krebs cycle happens once for every ______ molecule & goes round 2x for every ______ molecule

Answer 18

Krebs cycle happens once for every pyruvate molecule & goes round 2x for every glucose molecule

Question 19

Describe the Krebs cycle

Answer 19

1. Acetyl CoA combines with 4C to form 6C
   
   1. CoA A goes back to link reaction to be used again
2. 6C → 5C
   
   1. Decarboxylation occurs
   2. Dehydrogenation occurs
   3. H is used to NAD → reduced NAD
3. 5C → 4C
   
   1. Decarboxylation and dehydrogenation occur, produced 1x reduced FAD & 2x reduced NAD
   2. ATP is produced by direct transfer of phosphate group from intermediate compound to ADP
      
      1. Called substrate-level phosphorylation

Question 20

Answer 20

Question 21

Define oxidative phosphorylation

Answer 21

• Process where energy carried by electrons, from reduced coenzymes (reduced NAD and reduced FAD), is used to make ATP
• Involves electron transport chain and chemiosmosis

Question 22

Describe Oxidative Phosphorylation

Answer 22

1. Reduced NAD → NAD & reduced FAD → FAD = releases H
   
   • H atoms split into protons and e⁻
2. e⁻ move down electron transport chain, losing energy at each carrier
3. Energy is used to pump protons from mitochondrial matrix into intermembrane space
4. Conc. of protons is now higher in intermembrane space than in mitochondrial matrix
   
   • Forms electrochemical gradient
5. Protons move down electrochemical gradient into mitochondrial matrix via ATP synthase
   
   • Movement drives synthesis of ATP from ADP and P¡
6. In mitochondrial matrix, at end of transport chain, protons, electrons and O₂ (from blood) combine to form water
   
   • O₂ = final electron acceptor

Question 23

____ ATP are made from each reduced NAD and ___ ATP are made from each reduced FAD

Answer 23

2.5 ATP are made from each reduced NAD and 1.5 ATP are made from each reduced FAD

Question 24

Answer 24

Question 25

What do mitochondrial diseases affect?

Answer 25

* Affect functioning of mitochondria * Affect how proteins involved in oxidative phosphorylation or Krebs cycle function = reducing ATP production

Question 26

Describe the effect of mitochondrial diseases

Answer 26

1. May cause anaerobic respiration to increase, to try and make up some of the ATP shortage 2. = lots of lactate being produced, which can cause muscle fatigue and weakness 3. Some lactate will diffuse into bloodstream = high lactate concentrations in blood

Question 27

Describe how proteins can be used as respiratory substrates

Answer 27

1. Amino acids used as respiratory substances 2. Those not used for protein synthesis are deaminated in liver cells 3. Remainder of molecule can be converted into glycogen or fat 4. If there's not enough carbohydrates, muscle proteins can be hydrolysed to amino acids

Question 28

Describe how glycerol can be used as a respiratory substrate

Answer 28

Glycerol oxidised and phosphorylated into TP and then enters end of glycolysis

Question 29

Describe how fatty acids can be used as a respiratory substrate

Answer 29

Fatty acids are broken down by process known as beta oxidation to produce acetyl CoA when then enters the Krebs cycle

Question 30

What is produced a lot in beta oxidation?

Answer 30

Large amounts of FADH₂ and NADH

Question 31

Fatty acids can only be broken down \_\_\_\_\_\_\_

Answer 31

aerobically

Question 32

Why can fatty acids only be broken down aerobically?

Answer 32

∵ oxygen will be required as final electron acceptor

Question 33

Why do red blood cells only respire glucose?

Answer 33

Have no mitochondria - only respire anaerobically (lipids and proteins require aerobic conditions)

Question 34

What is the respiratory quotient

Answer 34

Is the ratio of CO₂ to O₂ in relation to a given respiratory substrate

Question 35

Describe how RQ values can be determined experimentally

Answer 35

By measuring O₂ consumption and CO₂ production using a respirometer

Question 36

By calculating RQ value, what can you find out?

Answer 36

* Substrates being used in respiration by an organism * Type of respiration being carried out can be deduced

Question 37

State the equation for calculating RQ

Answer 37

RQ = moles of CO₂ given out ————————————— Moles of O₂ taken in

Question 38

Work out the RQ for glucose

Answer 38

RQ = 6CO₂ ——— 6O₂ oxidised and phosphorylated RQ = 1

Question 39

RQ \< 1, it’s a ____ or \_\_\_

Answer 39

protein or lipid

Question 40

The production of ethanol or lactate regenerates oxidised NAD. Why is this good?

Answer 40

* Means glycolysis can continue when there isn't much oxygen around * ∴ small amount of ATP can be produced to keep some biological processes going

Question 41

Describe how you would investigate the effect of temperature on the rate of respiration of yeast

Answer 41

1. Set water bath at 35°C 2. Label 5 test tubes 3. Shake yeast and glucose mixture 4. Add 2 cm³ of yeast and glucose mixture to each test tube 5. Place all test tubes in water bath and wait until their contents reach 35°C 6. Add 1 cm³ of methylene blue to test tube 1 7. Shake test tube for 10s 8. Time how long it takes for solution to change from blue to colourless 9. Repeat steps 6-8 for other 4 tubes 10. Repeat steps 1-9, but use temperatures of 40°C, 45°C, 50°C, 55°C

Question 42

Explain why methylene blue changes from blue to colourless

Answer 42

1. During aerobic respiration, transport of electrons is linked to synthesis of ATP 2. Electrons are taken up by methylene blue 3. When methylene blue is reduced, changes from blue to colourless

Question 43

What is a respirometer is used for?

Answer 43

Used to indicate rate of aerobic respiration by measuring amount of oxygen consumed by organism in one period of time

Question 44

Respirometer What happens to the volume of air in test tube with e.g. woodlice & why?

Answer 44

* Volume of air decreases due to oxygen consumed during respiration * All CO₂ absorbed by potassium hydroxide

Question 45

Respirometer What happens when the volume of air in the test tube with e.g. woodlice decreases (as oxygen is taken up)?

Answer 45

* Decrease pressure in test tube * Causes coloured fluid in capillary tube of manometer to move toward it

Question 46

Describe what happens to reduced NAD produced in Krebs cycle (3)

Answer 46

* Enters mitochondria * NADH → oxidised to NAD * Used to produce ATP

Question 47

Describe the part played by the inner membrane of mitochondrion in producing ATP (3)

Answer 47

* electrons transferred down electron transport chain * provides energy to take protons into intermembrane * protons pass through membrane, ATP synthase

Question 48

Glucose _______ \_\_\_\_\_\_ the mitochondrial \_\_\_\_\_\_\_

Answer 48

Glucose _cannot_ _cross_ the mitochondrial _membrane_

Question 49

Human synthesise more than their body mass of ATP each day. Explain why it is necessary for them to synthesise such a large amount of ATP. (2)

Answer 49

* ATP cannot be stored/is an immediate source of energy * ATP only releases a small amount of energy at a time

Question 50

What measurements should the student have taken to calculate the rate of aerobic respiration in mm³ of oxygen g^-1 h^-1 (3)

Answer 50

* Distance (drop moves) and time * Mass of organism * Diameter of tube

Question 51

Draw Glycolysis. Include no. of carbon.

Answer 51

Question 52

Draw the Link Reaction. Include no. of carbon.

Answer 52

Question 53

Draw the Krebs Cycle. Include no. of carbon.

Answer 53

Question 54

The mitochondria in muscles contain many cristae. Explain the advantage of this. (2)

Answer 54

* Larger surface area for oxidative phosphorylation * Provide ATP / energy for contraction

Question 55

Explain why cells gain more energy from lipid than from carbohydrate (3)

Answer 55

* More H in lipid * More protons so more reduced FAD/NAD/(more protons) move across inner mitochondrial membrane * More ATP produced * More electrons moving down ETC

Question 56

Explain why less energy is released in anaerobic respiration (1)

Answer 56

Glucose only partly broken down/broken down to lactate

Question 57

At the end of a sprint race, a runner continues to breathe rapidly for some time. Explain the advantage of this. (2)

Answer 57

* Lactate built up * Oxygen used to break down lactate/convert it back to pyruvate

Question 58

Respiration Experiment State how temperature could be controlled

Answer 58

Using a water bath

Question 59

Respiration Experiment State how pH could be controlled

Answer 59

Using a buffer solution

Question 60

Explain why the scientist adds pyruvate rather than glucose to the isolated mitochondria (2)

Answer 60

* Glycolysis occurs in cytoplasm * Glycolsis produces pyruvate

Question 61

Explain why muscles become fatigued when insufficient oxygen is available (2)

Answer 61

* build up / increased concentration of lactate lowers pH / increases H / increases acidity * enzymes / named protein inhibited(not denatured)