A-Level Biology Unit 4: Chapter 4

Aerobic Respiration Common Exam Questions and Model Answers

General Questions:

· Tick boxes in table to show if NAD / ATP / CO2 produced in Glycolysis / Link / Krebs and location of stages

· Write in names of substances / how many C-atoms in the substance

· Label on mitochondria diagram where stages occur (for ETC label the inner membrane)

Experiment done on isolated mitochondria. Why was glucose not used as a respiratory substrate?

1. Glucose is broken down during glycolysis in cytoplasm;

2. Glucose cannot cross mitochondrial membrane;

How is oxygen used? (question comes in various forms)

· Oxygen used as final/terminal (electron) acceptor in the electron transport chain

· Electrons cannot be passed along electron transport chain if there is no oxygen to accept them

· Therefore used to generate ATP

· Accepts H+ to form water

Respirometer/Manometer experiment. Why did the air bubble move (has come up twice)

· Oxygen used in respiration

· Carbon dioxide (given out) is absorbed by solution/potassium hydroxide;

· Decrease in volume / pressure (inside flask);

Describe the part played by the inner membrane of a mitochondrion in producing ATP.

· Electrons transferred down electron transport chain;

· Provide energy to take protons/H+ into space between membranes;

· Protons/H+ pass back, through membrane/into matrix/through ATPase;

· Energy used to combine ADP and phosphate/to produce ATP;

In which step of respiration is carbon dioxide produced

Krebs / Link reaction

How would temperature affect respiration (be specific in answer whether Q refers to increased or decreased temp)

Enzyme controlled; kinetic energy; collisions between E and S; number of E-S complexes formed

Describe how ATP is made in mitochondria

1. Substrate level phosphorylation / ATP produced in Krebs cycle;

2. Krebs cycle/link reaction produces reduced NAD/reduced FAD;

3. Electrons released from reduced NAD/FAD;

4. (Electrons) pass along carriers/through electron transport chain/through series of redox reactions;

5. Energy released;

6. ADP/ADP + Pi;

7. Protons move into intermembrane space;

8. ATP synthase;