A2 Recall

Question 1

Describe how acetyl coenzyme A is formed in the link reaction

Answer 1

1. Oxidation of pyruvate and carbon dioxide released

Question 2

In muscles, pyruvate is converted to lactate during anaerobic respiration. Explain why converting pyruvate to lactate allows the continued production of ATP during respiration

Answer 2

1. Regenerates NAD
2. NAD used in glycolysis

Question 3

ATP is useful in many biological processes. Explain why.

Answer 3

1. Releases energy in small amounts
2. Brown down in one step
3. Phosphorylates
4. Reformed

Question 4

Describe how ATP is made in mitochondria

Answer 4

1. Substrate level phosphorylation
2. Link reaction produces reduced coenzyme
3. Electrons released from reduced coenzymes (NAD/FAD)
4. Electrons pass through electron transport chain
5. Energy released
6. ADP+ Pi
7. Protons move into intermediate space
8. ATP synthase

Question 5

Plants produce ATP in their chloroplasts during photosynthesis. They also produce ATP during respiration. Explain why it is important for plants to produce ATP during respiration in addition to during photosynthesis.

Answer 5

1. In the dark no ATP production in photosynthesis
2. Some tissues unable to photosynthesise
3. ATP cannot be moved from cell to cell
4. Plant uses more ATP than produced in photosynthesis
5. ATP for active transport

Question 6

Explain why oxygen is needed for the production of ATP on the cristae of the mitochondrion

Answer 6

1. ATP is formed as electrons pass along transport chain
2. Oxygen is terminal electron acceptor
3. Forms water

Question 7

Human skeletal muscle can respire both aerobically and anaerobically. Describe what happens to pyruvate in anaerobic conditions and explain why anaerobic respiration is advantageous to human skeletal muscle.

Answer 7

1. Forms lactate
2. Use of reduced NAD
   3.Regenerates NAD
3. Can still release energy when oxygen in short supply

Question 8

Without oxygen, less ATP is produced by respiration. Explain why.

Answer 8

1. Oxygen is the terminal acceptor
2. Which produces most of the ATP
3. Only produces 2 ATP per molecule of glucose

Question 9

Mitochondria in muscle cells have more cristae than mitochondria in skin cells. Explain the advantage of mitochondria in muscle cells having more cristae.

Answer 9

1. More cristae
2. More enzymes for ATP production
3. Muscle cells use more ATP

Question 10

Describe the roles of the coenzymes and carrier proteins in the synthesis of ATP

Answer 10

1. NAD/ FAD reduced
   2.Electrons transferred from coenzyme to coenzyme
2. Energy made available as electrons passed on
3. Energy used to synthesise ATP from ADP and phosphate
4. Protons passed into intermediate space
5. Protons flow back through stalked particles