5.2.2 - Respiration

Question 1

Why is cellular respiration required by all living organisms ?

Answer 1

• All living organisms respire
• Energ is required by cells to carry out many activities and processes that maintain life

Question 2

What are the uses of cellular respiration ?

Answer 2

• Transport of substances across membranes ( eg. Exocsytosis )
• Anabolic reactions ( eg. Synthesis of DNA from nucleotides/ proteins from amino acids )
• Movement ( eg. Muscle contraction )
• Maintaing body temperature

Question 3

What are the different types of respiration ?

Answer 3

• Aerobic respiration
• Anaerobic respiration

Question 4

Define the term ‘Aerobic respiration’ ?

Answer 4

Aerobic respiration - The process by which organisms break down glucose in the presence of oxygen to produce energy in the form of ATP

Question 5

Define the term ‘Anaerobic respiration’ ?

Answer 5

Anaerobic respiration - The process of breaking down glucose to release energy in the absence of oxygen to produce nervy in the form ATP

Question 6

When does aerobic and anaerobic respiration occur ?

Answer 6

• Aerobic respiration occurs in a plentiful supply of oxygen
• During aerobic respiration, glucose is broken down in the presence of oxygen
• Anaerobic respiration occurs in a low/ lack supply of oxygen
• During anaerobic respiration, glucose is broken down in the absence of oxygen

Question 7

What is the word equation for aerobic respiration ?

Answer 7

Glucose + Oxygen —> Water + Carbon dioxide

Question 8

What is the equation for aerobic respiration used?

Answer 8

Cv6Hv120v6 + 6Ov2 → 6COv2 + 6Hv20

Question 9

What is the word equation for anaerobic respiration used?

Answer 9

Glucose —> Lactate

Question 10

What is the equation for anaerobic respiration used?

Answer 10

Cv6Hv120v6 —> 2Cv3Hv60v3

Question 11

Where does aerobic respiration occur ?

Answer 11

In the mitochondria

Question 12

What is the role of the mitochondria ?

Answer 12

• It is the site of aerobic respiration
• It is responsible for synthesising ATP ( during the last stage of respiration called oxidative phosphorylation )

Question 13

Label the different structures of the mitochondria ?

Answer 13

Question 14

What of the features of the outer membrane ?

Answer 14

• Smooth
• Permeable to several small molecules
• Separates the conditions of the mitochondria from the cytoplasm of the cell, creating ideal conditions for aerobic respiration

Question 15

What are the features of the inner membrane ?

Answer 15

• Folded /cristae
• Less permeable/ Impermeable to H+ ions
• The site of the electron transport chain / electron carriers and ATP synthase enzymes

Question 16

What are the features of the intermembrane spaces ?

Answer 16

• Protons are pumped into this space during oxidative phosphorylation and is essential for ATP synthesis
• Due to the small space, the contraction increases quickly and has a low pH due to the high concentration of protons

Question 17

What are the features of the mitochondrial matrix ?

Answer 17

• Is an aqueous solution within the inner membranes of the mitochondrion
• Contains ribosomes, enzymes for the Krebs cycle and link reactions
• Also contains circular mitochondrial DNA necessary for mitochondria to function

Question 18

What is the role of cristae ?

Answer 18

• Cristae / inner foldings of the inner membrane produce a large surface area for oxidative phosphorylation
• This enables the membrane to hold many electron transport chain proteins and ATP synthase enzymes

Question 19

Why would cells have a greater number of/ larger mitochondria ?

Answer 19

• More active cell types can have larger mitochondria with longer and more tightly packed cristae to enable the synthesis of more ATP because they have a larger surface area
• The number of mitochondria in each cell can vary depending on cell activity

Question 20

What are the four stages of aerobic respiration ?

Answer 20

• Glycolysis
• The Link reaction
• The Krebs cycle
• Oxidative phosphorylation

Question 21

Where does each stage of aerobic respiration occur ?

Answer 21

• Glycolysis ( cell cytoplasm )
• The Link reaction ( Matrix of mitochondria )
• The Krebs cycle ( Matrix of mitochondria )
• Oxidative phosphorylation ( Inner membrane of mitochondria )

Question 22

What are the products of glycolysis ?

Answer 22

• 2 Pyruvate (3C) molecules
• Net gain 2 ATP
• 2 reduced NAD

Question 23

Name examples of substrate-level phosphorylation throughout all the stages ?

Answer 23

• During glycolysis, to produce 4 molecules of ATP resulting. in net gain of 2 ATP molecules
• During glycolysis, when triose (bis)phosphate is being converted to pyruvate
• During Krebs cycle, to produce 1 molecule of ATP
• During Krebs cycle when intermediate compound is converted to oxaloacetate

Question 24

Draw a diagram showing all the stages of glycolysis ?

Answer 24

Question 25

What is the role of the Link Reaction ?

Answer 25

It links Glycolysis to the Krebs Cycle

Question 26

Draw a diagram showing what happens during the Link Reaction ?

Answer 26

Question 27

What are the products of the Link Reaction ?

Answer 27

- Acetyl coA - Carbon dioxide (CO2) - Reduced NAD (NADH)

Question 28

What is the role of the coenzyme A in the Link Reaction ?

Answer 28

It transfers the acetyl group/ acetate from the link reaction into the Krebs cycle by binding to it

Question 29

What is the role of NAD and FAD ?

Answer 29

They are hydrogen acceptors/ they accept hydrogen atoms to from reduced NAD and reduced FAD

Question 30

Explain the role of NAD and FAD during all the stages ?

Answer 30

- NAD and FAD accept hydrogen atoms to form NADH and FADH - During glycolysis, when triose (bis)phosphate is converted into pyruvate - During the link reaction, when pyruvate is converted into acetate - During the Kreb's cycle, when citrate is converted into intermediate command and when intermediate compound is converted into oxaloacetate - During oxidative phosphorylation, they add electrons to electron transport chain

Question 31

Explain the role of ADP/ATP during all the stages ?

Answer 31

- ATP is formed during substrate-level phosphorylation - During glycolysis, add phosphate groups to glucose to from hexose-1,6-bisphosphate - Dephosphoryltion of phosphate groups from triose phosphate to form pyruvate - During Krebs cycle, dephosphrylation of intermediate compound

Question 32

What Is substrate-level phosphorylation ?

Answer 32

- Phosphorylation ONLY when ATP is generator from ADP by adding phosphaye group - ATP —> ADP + Pi IS NOT SUBSTRATE LEVEL- PHOSPHORLYATION, JUST PHOSPHORLYATION OF MOLECULE

Question 33

What is another name for the Krebs cycle ?

Answer 33

The citric acid cycle

Question 34

Draw the diagram explaining the Krebs cycle ?

Answer 34

Question 35

Explain how the intermediate compound is converted into oxaloacetate ?

Answer 35

- It will undergo decarboxylation, producing COv2 - It will undergo Dehydrogenation, forming NADH and FADH from NAD and FAD - Phosphorylation of ADP occurs producing 1 molecule of ATP

Question 36

What is produced during oxidative phosphorylation ?

Answer 36

- ATP - Water

Question 37

Explain how ATP is synthesised via chemiosmosis ?

Answer 37

- Energy at each electron carrier is used to pump protons across the membrane, from the mitochondrial matrix into the inter-membrane spaces via active transport - This creates a proton gradient - This causes protons to move down the proton gradient from an area of high concentration to an area of low concentration via ATP synthase back into the mitochondrial matrix - This movement of protons via ATP synths drives the formation of ATP from ADP + Pi

Question 38

Explain why chemiosmosis may be not completely efficient ?

Answer 38

- Some H+ ions leak back into the mitochondrial matrix through proton pores - This means less ATP is synthesised / reducing yield of ATP from chemiosmosis

Question 39

Describe what happens during oxidative phosphorylation ( Part 1 )?

Answer 39

- H atoms are released by NADH and FADH - H atoms split into protons and electrons - Electrons move along the electron-transport-chain ( consisting of at least 3 electron carriers ) releasing energy at each electron carrier in a series of redox reactions - This energy is used by each electron carrier to pump protons, via active transport, from the mitochondrial matrix into the inter-membrane space across the membrane - There is now a higher concentration of protons in the inter-membrane space than mitochondrial matrix establishing an electrochemical/ PROTON concentration gradient

Question 40

Describe what happens during oxidative phosphorylation ( Part 2 ) ?

Answer 40

- Protons move down the electrochemical/ PROTON concentration gradient back into the mitochondrial matrix via ATP synthase - The movement of protons via ATP synthase drives the synthesis of ATP from ADP and Pi ; called chemiosmosis - In the matrix, at then end of electron transport chain, protons, electrons and oxygen from the blood combine to form water - Oxygen acts as the final electron acceptor - Without oxygen, H atoms would not be removed and would ‘back up’ along the electron transport chain stopping respiration

Question 41

Draw a diagram showing what happens in oxidative phosphorylation ?

Answer 41

Question 42

What are the consequences of anaerobic respiration ?

Answer 42

- No oxygen to act as final electron/ hydrogen acceptor - Only glycolysis - No links reaction, revs cycle or oxidative phosphorylation - The electron transport chain stops functioning - Less ATP is produced ( 2 molecules instead of 36 molecules )

Question 43

What are the anaerobic pathways to synthesise ATP ?

Answer 43

- Ethanol fermentation - Lactate fermentation

Question 44

Draw a diagram showing what happens during ethanol fermentation ?

Answer 44

Question 45

Draw a diagram showing what happens during lactate fermentation ?

Answer 45

Question 46

Explain why anaerobic respiration is bad for plants long-term ?

Answer 46

- Ethanol is toxic - It is irreversible - Less ATP is produced - This means plant cannot synthesise DNA/ proteins - This means plants cannot carry out active transport ( mineral ions into root hair cells ) - No water potential gradient is generated in roots so water cannot be absorbed - Less/ no photosynthesis

Question 47

What can happen when lactate is produced ?

Answer 47

- It can be oxidised back to pyruvate which is then channelled into the Krebs cycle for ATP production - It can be converted into glycogen for storage in the liver

Question 48

What enzymes are involved in Animalia and plant anaerobic respiration ?

Answer 48

- Animal anaerobic respiration : lactate dehydrogenase - Plant anaerobic respiration : pyruvate decarboxylase

Question 49

What happens when lactate is oxidised back to pyruvate ?

Answer 49

- Oxidation of lactate to pyruvate requires extra oxygen which is referred to as oxygen debt - It explains why animals breathe deeper and faster after exercise

Question 50

What are examples of respiratory substrates for aerobic respiration ?

Answer 50

- Glucose - Other carbohydrates - Lipids - Proteins

Question 51

Explain why different respiratory substrates have different energy values ?

Answer 51

- Fatty acids, then proteins and then carbohydrates have the highest energy content - Fatty acids contain the most hydrogen atoms - This means they can be oxidised many times during the Krebs cycle - This results in more NADH and FADH molecules being produced resulting in more ATP being produced during oxidative phosphorylation

Question 52

Compare aerobic and anaerobic respiration in terms of stages involves, oxidation of glucose, total ATP produced, location and products ?

Answer 52

Question 53

What are the RQ values of different respiratory substrates ?

Answer 53

Question 54

What is the respiratory quotient ( RQ ) ?

Answer 54

The respiratory quotient (RQ) is: the ratio of carbon dioxide molecules produced to oxygen molecules taken in during respiration

Question 55

What is the equation for the respiratory quotient ?

Answer 55

RQ = COv2 produced / Ov2 consumed