Respiration

Question 1

What are the 4 stages in aerobic respiration?

Answer 1

Glycolysis - occurs in the cytoplasm
Link reaction - occurs in the mitochondrial matrix
Krebs cycle - mitochondrial matrix
Oxidative phosphorylation - via electron transfer chain : membrane of cristae

Question 2

How does pyruvate from glycolysis enter the mitochondria?

Answer 2

Active transport

Question 3

What are the net products from glycolysis?

Answer 3

2 ATP molecules
2 NADH molecules
2 pyruvate molecules

Question 4

What are the steps of glycolysis?

Answer 4

Phosphorylation of glucose into glucose phosphate using ATP. Glucose is activated and has a lower activation energy.
Triose phosphate is produced from splitting the phosphorylated glucose.
Triose phosphate is oxidised (H removed) to pyruvate and NAD is reduced to NADH
ADP converted into ATP - net gain of ATP

Question 5

Where does the link reaction occur?

Answer 5

Mitochondrial matrix

Question 6

What are the steps in the link reaction?

Answer 6

Pyruvate is oxidised to acetate
Produces reduced NAD and carbon dioxide is lost/removed
Acetate combines with coenzyme A
Produces acetyl coenzyme A

Question 7

Where does the Krebs cycle occur?

Answer 7

Mitochondrial matrix

Question 8

Where does the Krebs cycle occur?

Answer 8

Mitochondrial matrix

Question 9

What are the products of the Krebs cycle

Answer 9

1 reduced FAD
3 reduced NAD
1 ATP
2 carbon dioxide

Question 10

What are the products of the Krebs cycle

Answer 10

1 reduced FAD
3 reduced NAD
1 ATP
2 carbon dioxide

Question 11

Steps of the Krebs cycle

Answer 11

Acetyl coenzyme A gives the 2 carbon acetate to a 4 carbon molecule.
The 6 carbon molecule undergoes reactions (decarboxylation, releasing NADH and reduced FAD)
Eventually, the 4 carbon molecule is regenerated and the Krebs cycle turns again.