Key Area 2

Question 1

What is glycolysis?

Answer 1

The breakdown of glucose to pyruvate in the cytoplasm

Question 2

Describe glycolysis

Answer 2

1. ATP is required for the phosphorylation of glucose and intermediates during the energy investment phase (uses 2 ATP)
2. This leads to the generation of more ATP during the energy payoff stage(regeneration of 4 ATP) and results in a net gain (2 ATP)

Question 3

Describe what happens after glycolysis in aerobic conditions

Answer 3

Citric acid cycle

1. Pyruvate is broken down to an acetyl group that combines with coenzyme A forming acetyl coenzyme A
2. In the citric acid cycle the acetyl group from acetyl coenzyme A combines with oxaloacetate to form citrate
   3.during a series of enzyme controlled steps citrate is gradually converted back into oxaloacetate which results in the generation of ATP and release of carbon dioxide
3. Happens in the matrix of the mitochondria

Question 4

What do dehydrogenase enzymes do?

Answer 4

Remove hydrogen ions and electrons to pass them to the coenzyme NAD to form NADH

Question 5

How is ATP synthesised

Answer 5

1. Electrons are passed along the electron transport chain releasing energy
   2.hydrogen ions are pumped across the inner mitochondrial membrane
2. Ions flow back through the membrane protein ATP synthase
3. Hydrogen ions and electrons combine with oxygen to form water

Question 6

What process happens in the absence of oxygen?

Answer 6

Fermentation in the cytoplasm

Question 7

What is pyruvate converted to in animal cells?

Answer 7

Lactate and it is a reversible reaction

Question 8

What is pyruvate converted into in plant and yeast cells?

Answer 8

Ethanol and CO2 and it is an irreversible reaction

Question 9

How does fermentation compare to aerobic respiration in ATP production

Answer 9

Much less ATP is produced

Question 10

What is ATP used for?

Answer 10

To transfer energy to cellular processes which require energy