Respiration

Question 1

Where do the 4 stages of respiration occur?

Answer 1

1. Glycolysis in the cytoplasm
2. The link reaction in the fluid matrix of the mitochondrion
3. Krebs cycle within the fluid matrix of the mitochondrion
4. ETC on the cristae of the mitochondrion

Question 2

What is the first step of Glycolysis?

Answer 2

Glucose is activated by phosphorylation.

Question 3

What is the second step of Glycolysis?

Answer 3

The activated glucose molecule is split in 2, producing two triose molecules.

Question 4

What is the third step of Glycolysis?

Answer 4

Each triose molecule is oxidised by removing two hydrogen atoms. These are transferred to co-enzyme NAD to form NADH.

Question 5

What is the fourth step of Glycolysis?

Answer 5

Each triose phosphate into pyruvate. During this process, two ATP molecules are generated.

Question 6

What are coenzymes?

Answer 6

Molecules that bind with specific enzymes or substrates, helping to catalyse a reaction.

Question 7

What are the three major coenzymes used in respiration?

Answer 7

• NAD
• Coenzyme A
• FAD

Question 8

What does NAD do?

Answer 8

NAD can accept a hydrogen molecule, forming NADH, which is used to regenerate ADP in the ETC.

Question 9

What does Coenzyme A do?

Answer 9

Coenzyme A aids the transition between glycolysis and the Krebs cycle, by converting pyruvate to acetyle coenzyme A.

Question 10

What does FAD do?

Question 11

What does the Link Reaction link?

Answer 11

T

Question 12

Where does the Link Reaction take place?

Question 13

What is released in the Link Reaction?

Answer 13

CO₂ and NADH.

Question 14

What is the first step of the Krebs Cycle?

Question 15

What is the second step of the Krebs Cycle?

Answer 15

Citrate is decarboxylated, releasing 1 CO₂. It also releases two H atoms to reduced NAD⁺.

Question 16

What is the third step of the Krebs Cycle?

Question 17

What is the fifth step of the Krebs Cycle?

Answer 17

This step involves dehydrogenation. Two H atoms are released.