Respiration

Question 1

What are the 4 stages of aerobic respiration?

Answer 1

Glycolysis, link reaction, Krebs cycle and oxidative phosphorylation

Question 2

What’s a summary of glycolysis?

Answer 2

Splitting of 6-carbon glucose to to two 3-carbon pyruvate molecules

Question 3

What’s a summary of the link reaction?

Answer 3

3-carbon pyruvate enter into a series of reactions which lead to the formation of acetylcoenzyme A, a 2-carbon molecule

Question 4

What’s a summary of the Krebs cycle?

Answer 4

Introduction of acetylcoenzyme A into a series of redox reactions that yield some ATP and a large quantity of reduced NAD and FAD

Question 5

What’s oxidative phosphorylation?

Answer 5

the use of electrons, associated with reduced NAD and FAD, released from the Krebs cycle to synthesise ATP with water produced as a by-product

Question 6

What co-enzymes are involved in respiration?

Answer 6

NAD, CoA and FAD

Question 7

What does CoA do?

Answer 7

Carries ethanoate groups created in the link reaction through to the Krebs cycle

Question 8

Why is glycolysis anaerobic?

Answer 8

Doesn’t require oxygen

Question 9

What molecules are used and formed in phosphorylation stage of glycolysis?

Answer 9

ATP used to make hexose phosphate then another ATP used for hexose biphosphate formation

Question 10

What molecules are used and formed in oxidation stage of glycolysis?

Answer 10

Hexose biphosphate is hydrolysed into two triose phosphate then 4ADP and 2NAD produce 4ATP and 2NADH for two pyruvate molecules

Question 11

What are the products of glycolysis?

Answer 11

Net gain 2 ATP, 2 NADH and 2 pyruvate molecules

Question 12

Why does the link reaction depend on oxygen?

Answer 12

Pyruvate needs to be passed into the mitochondria via active transport

Question 13

What are the stages of link reaction?

Answer 13

Pyruvate oxidises NADH to NAD and releases CO2, it’s converted to acetate, which then combines with Coenzyme A to form Acetyl Coenzyme A

Question 14

What are the products of one link reaction?

Answer 14

NADH, CO2 and Acetyl Coenzyme A

Question 15

What’s the first step in the Krebs cycle?

Answer 15

Acetyl Coenzyme A reacts with Oxaloacetate to form Citrate (citric acid) and the Coenzyme A is released.

Question 16

What happens to the citrate in the Krebs cycle?

Answer 16

CO2 is released and NADH is formed for a 5C molecule. The same to produce a 4C molecule. ATP is formed (new 4C). FADH is formed (new 4C). NADH is formed (new 4C, oxaloacetate).

Question 17

What is decarboxylation?

Answer 17

Release of CO2 in Krebs cycle

Question 18

What is dehydrogenation?

Answer 18

Reduction of NAD in Krebs cycle

Question 19

What are the products on one Kreb cycle?

Answer 19

2 CO2, 1 ATP and 4 pairs of hydrogen atoms

Question 20

What does the electron transport chain do?

Answer 20

Makes ATP from reduced NAD and FAD made in earlier stages

Question 21

What happens at the electron transfer chain?

Answer 21

Coenzymes are oxidised at electron carriers and H+ move to the intermembrane space and electrons move down electron carriers

Question 22

What’s the consequence of H+ electrochemical gradient?

Answer 22

Protons diffuse through inner mitochondrial membrane down ATP synthase and catalyse the production of ATP

Question 23

What happens to electrons in the electron transfer chain?

Answer 23

The combine with protons to form hydrogen atoms which then combine with oxygen to create water

Question 24

Which complex in ETC does FADH bind to?

Answer 24

II

Question 25

Which complexes pump protons through?

Answer 25

I, II and IV

Question 26

How many protons moved through for NADH?

Answer 26

10

Question 27

How many protons pumped for FADH?

Answer 27

6

Question 28

What happens to pyruvate in anaerobic respiration?

Answer 28

Pyruvate is oxidised by NADH to lactate and NAD is produced

Question 29

What do plants and some microorganisms convert pyruvate to?

Answer 29

Ethanol as it loses CO2 and accepts hydrogen from reduced NAD

Question 30

What’s the intermediate in ethanol production?

Answer 30

Acetylaldehyde

Question 31

What co-enzymes are created in anaerobic in plants?

Answer 31

NAD created

Question 32

Why is anaerobic respiration important?

Answer 32

NADH is converted to NAD when the hydrogen atoms are added to pyruvate, this allows glycolysis to continue

Question 33

How are lipids used for respiration?

Answer 33

Hydrolysed to glycerol and fatty acids, glycerol is then phosphorylated to TP and fatty acids are converted to acetyl coenzyme A

Question 34

Why are lipids more energy dense than carbohydrates?

Answer 34

Oxidation of lipids produces 2 carbon fragments and many hydrogen atoms, these can be used in ATP synthase

Question 35

How are proteins used for respiration?

Answer 35

Hydrolysed to amino acids, the amino group is removed (deamination), 3 carbon compound are converted to pyruvate and 4 and 5 carbon compounds are converted to intermediates in the Krebs cycle