Chapter 12 - Respiration

Question 1

Summarise aerobic respiration

Answer 1

• Oxygen required
• More efficient as more ATP reduced
• Complete breakdown of glucose to form CO2

Question 2

Summarise anaerobic respiration

Answer 2

• Does not need oxygen
• Less efficient as less ATP produced
• Incomplete breakdown of glucose and produces lactic acid in bacteria and animals/ethanol in plants and yeast

Question 3

Summarise Glycolysis

Answer 3

• Occurs in the cytoplasm
• Glucose phosphorylated by ATP into GP
• GP phosphorylated into hexose bisphosphate
• Two molecules of TP formed
• Each TP oxidised into Pyruvate by NAD to form NADH
• Oxidisation of TP forms two ATP molecules
• Net yield of 2 ATP and 2 NADH
• Pyruvate actively transported into mitochondrion for link reaction

Question 4

Summarise the Link reaction

Answer 4

• Occurs in matrix
• Pyruvate decarboxylated and dehydrogenated (oxidised) to form Acetate
• Acetate combines with coenzyme A to form Acetylcoenzyme A
• Net yield of 1 CO2 and 1 NADH for each pyruvate

Question 5

Summarise the Krebs cycle

Answer 5

• Occurs in matrix
• Acetylcoenzyme A combines with 4C oxaloacetate to form 6C citrate
• 6C molecule decarboxylated and oxidised and NAD reduced to form NADH and 5C molecule
• 5C molecule decarboxylated and oxidised and 2NAD reduced to form 2NADH to and 4C molecule
• 5C - 4C also reduces FAD top FADH and produces ATP from ADP and Pi
• Net yield 3 NADH, 1 ATP, 1 FADH

Question 6

Summarise oxidative phosphorylation

Answer 6

• Occurs in inner mitochondrial inner membrane
• Reduced NADH and FADH oxidised to release H+ and e-
• e- released into electron transport chain and travels down providing energy to proton pumps
• Proton pumps H+ ions into intermembrane space
• Gradient causes H+ to diffuse back into matrix through ATP synthase
• O2 used as final electron and H+ acceptor to produce water to maintain gradient

Question 7

Summarise anaerobic respiration in animals/bacteria

Answer 7

• Glycolysis as normal

- Pyruvate oxidised into lactate by NADH to reform NAD

Question 8

Summarise anaerobic respiration in plants/yeast

Answer 8

• Glycolysis as normal

- Pyruvate decarboxylated into ethanal and ethanal reduced into ethanol by NADH to reform NAD

Question 9

What is a respiratory substrate?

Answer 9

• Biological molecule that can be respired to release energy

Question 10

Which respiratory substrates produce the most/least energy?

Answer 10

Lipid = Most
Protein = Medium
Carbohydrate = Least