Topic 5 - Respiration

Question 1

What is step one of anaerobic and aerobic respiration?

Answer 1

Glycolysis

Question 2

Where in the cell does glycolysis occur?

Answer 2

In the cytoplasm

Question 3

What are the 3 key steps in glycolysis?

Answer 3

1. Phosphorylating glucose to glucose phosphate, using two molecules of ATP.
2. The production of triose phosphate.
3. Oxidation of triose phosphate to produce pyruvate.

Question 4

What happens to the net gain of ATP and reduced NAD?

Answer 4

Pyruvate and NADH are actively transported from the cytoplasm into the mitochondrial matrix.

Question 5

What are the products of glycolysis?

Answer 5

2x pyruvate
Net gain of 2x ATP
2x NADH

Question 6

What are the 3 main steps of the link reaction?

Answer 6

1. The pyruvate made in glycolysis is oxidised to acetate.
2. NAD picks up the hydrogen and becomes reduced NAD (NADH)
3. Acetate then combines with coenzyme A to produce acetyl coenzyme A

Question 7

What are the products of the link reaction for every glucose molecule?

Answer 7

2x Acetyl CoA
2x CO2
2x NADH

Question 8

What are the two main steps in the Kreb’s cycle?

Answer 8

1. Acetyl CoA reacts with a 4C molecule releasing CoA and producing 6C molecule that enters the Kreb cycle.
2. In a series of redox reactions, the Krebs cycle generates reduced coenzymes and ATP by substrate level phosphorylation and CO2 is lost.

Question 9

What are the products of the krebs cycle per cycle?

Answer 9

3x NADH
1x FADH
1x ATP
2x CO2

Question 10

What are the products of the krebs cycle per glucose molecule?

Answer 10

6x NADH
2x FADH
2x ATP
4x CO2

Question 11

What does oxydative phosphorylation involve?

Answer 11

Involves:
- The electron transfer chain
- Movement of protons across the inner mitochondrial membrane
- Catalysed by ATP synthase

Question 12

Explain the process of adaptive phosphorylation.

Answer 12

1. NADH and FADH coenzymes deliver their elections to the first protein in the ETC.
2. Elections are passed along the ETC in a series of redox reactions.
3. As the electrons more along, energy is released which provides energy to pump H+ into the intermembrane space.
4. This causes an electrochemical gradient to be established.
5. H+ can diffuse back into the centre of the mitochondria through ATP synthase enzyme. The ATP synthase turns as the H+ moves through, making ATP from ADP and Pi as it does so.
6. Oxygen in the matrix picks up the electrons at the end of the ETC as well as protons to form H2O. (oxygen is the final electron acceptor)

Question 13

Where in the cell does glycolysis occur?

Answer 13

Cytoplasm

Question 14

Where in the cell does the link reaction occur?

Answer 14

In the mitochondrial matrix.

Question 15

Where in the cell does the krebs cycle occur?

Answer 15

In the mitochondrial matrix

Question 16

Where in the cell does oxidative phosphorylation occur?

Answer 16

In the mitochondrial cristae.

Question 17

Where does anaerobic respiration occur?

Answer 17

In the cytoplasm only.

Question 18

What is pyruvate reduced to in anaerobic respiration?

Answer 18

Pyruvate is reduced to form ethanol and CO2 in plants and lactate in animals.

This oxidises NAD so that it can be reused in glycolysis and ensure more ATP is continued to be produced.