Respiration

Question 1

Describe how a 6-carbon molecule of glucose is converted to pyruvate. 6marks

Answer 1

• Glucose is phosphorylated
• By adding 2phosphates from 2 molecules of ATP
• This creates phosphorylated glucose and 2 molecules of triose phosphate
• triose phosphate is oxidised to give 2 molecules of pyruvate
• the hydrogen is accepted by 2 molecules of NAD producing 2 molecules of rNAD
• during oxidation 4 molecules of ATP are produced.

Question 2

Write down an equation to show how lactate is produced. 2 marks

Answer 2

Pyruvate + rNAD -> lactate + NAD

Question 3

What is the advantage of producing lactate in anaerobic respiration. 2 marks

Answer 3

• lactate is produced to regenerate NAD
• so glycolysis can continue and ATP can be produced under anaerobic conditions to provide energy for biological processes

Question 4

Carbon monoxide inhibits the final electron carrier in the electron transport chain.
A) explain how this affects ATP production via the electron transport chain. 2 marks

Answer 4

• transfer of electrons down the electron transport chain stops
• so no energy released to produce ATP

Question 5

Carbon monoxide inhibits the final electron carrier in the electron transport chain.
B) explain how this affects ATP production via the Krebs cycle. 2 marks

Answer 5

• the Krebs cycle stops

- because there is no oxidised NAD/FAD coming from the electron transport chain.