Section 5:Respiration

Question 1

What are the four steps of aerobic respiration?

Answer 1

1. Glycolysis
2. Link reaction
3. Krebs cycle
4. Oxidative phosphorylation

Question 2

Where do the stages of photosynthesis take place?

Answer 2

• Glycolysis=cytoplasm of the cell
• Link reaction and krebs cycle=matrix of the mitochondrian
• Electron transport chain=cristae of the mitochondrian

Question 3

Describe the process of glycolysis

Answer 3

• Glucose(6C) is activated by phosphorylation~by the addition of 2 phosphate molecules from hydrolysis of 2 ATP (Phosphorylated glucose)
• This splitting forms two triose phosphates (3C) which are then oxidised
• This causes NAD to form reduced NAD by the addition of a H+ (this happens to two NAD molecules)
• 4 ATP molecules are made from ADP and inorganic phosphate
• The final product is two molecules of pyruvate

Question 4

What is NAD and FAD?

Answer 4

A ‘coenzyme’ needed by enzymes in order to function properly

Question 5

Describe the process of the link reaction in respiration

Answer 5

• Pyruvate is oxidised to acectate (2C)~the pyruvate loses a carbon dioxide molecule and 2 hydrogens
• These hydrogens are then accepted by NAD forming reduced NAD
• Acetate then combines with coenzyme A to form acetylcoenzyme A (2C)
• The acetyl coA then enters the krebs cycle

Question 6

Describe what happens in the krebs cycle

Answer 6

• acetylcoenzyme binds with a four carbon molecule
• This forms a 6 carbon molecule
• Reduced NAD is formed after accepting a hydrogen ion
• Two molecules of carbon dioxide are then created
• Reduced FAD is formed from FAD after accepting a hydrogen ion
• One molecule of ATP is produced
• The four carbon molecule is then regenerated

Question 7

Describe what happens during oxidative phosphorylation

Answer 7

• Hydrogen ions combine with NAD and FAD to form reduced NAD and reduced FAD
• Reduced NAD and reduced FAD is then pass to the electron transport chain in the cristae of the mitochondria
• Hydrogen ions + electrons removed from reduced NAD and reduced FAD
• Electron~transferred to a series of electron carriers
• Hydrogen ions~actively pumped across the inner mitochondrial membrane and accumulates in the space between the inner and the outer membranes
• Last electron carrier is oxygen which accepts H+ and e- to form water

Question 8

Define substrate phosphorylation

Answer 8

ATP molecules made directly by the enzymes in glycolysis or the krebs cycle

Question 9

Define oxidative phosphorylation

Answer 9

The production of ATP using energy released when electrons pass down the electron transport chain down the electron transport chain

Question 10

What is produced from the respiration of lipids?

Answer 10

Glycerol and fatty acids,glycerol is then converted into triose phosphate

Question 11

Why is the respiration of lipids better than carbohydrates?

Answer 11

Lipids release double the amout of energy than carbohydrates of an equal mass

Question 12

What is pyruvate converted to in anaerobic respiration?

Answer 12

• Converted into lactate in animals
• Converted into ethanol and carbon dioxide in plants and microorganisms

Question 13

Describe the process of anaerobic respiration

Answer 13

• In the absence of oxygen there is a build up of hydrigen ions as there is no oxygen to form water
• This means that all NAD and FAD becomes reduced and they cannot release their hydrogen ions
• To prevent build up of hydrogenions and allow glycolysis, pyruvate accepts hydrigen from reduced NAD, therefore regenerating NAD

Question 14

How is energy derived from cellular respiration?

Answer 14

• Substrate-level phosphorylation
• Oxidative phosphorylation

Question 15

What is substrate-level phosphorylation?

Answer 15

The dircet transfer of phosphate from a respiratory intermediate ADP to produce ATP

Question 16

What is oxidative phosphorylation?

Answer 16

The indirect linking of energy from phosphate to ADP to produce ATP