Respiration

Question 1

How may ATP molecules does aerobic respiration yield?

Answer 1

Up to 38 molecules of ATP

Question 2

How many ATP molecules does anaerobic respiration yield?

Answer 2

2 ATP molecules

Question 3

Where does glycolysis occur in the mitochondria?

Answer 3

Cytoplasm

Question 4

Where does the link reaction occur in the mitochondria?

Answer 4

Mitochondrial matrix

Question 5

Where does the kreb cycle occur in the mitochondria?

Answer 5

Mitochondrial matrix

Question 6

Where does oxidative phosphorylation occur in the mitochondria?

Answer 6

Cristae

Question 7

Describe the process of glycolysis.

Answer 7

1. Glucose is phosphorylated using 2ATP to produce glucose phosphate
2. Glucose phosphate splits to form 2 molecules of Triose Phosphate
3. Triose phosphate is oxidised to form pyruvate when 2NAD is reduced to 2NADH
4. A net gain of 2ATP is made by substrate level phosphorylation

Question 8

Describe the end of glycolysis if respiration is anaerobic.

Answer 8

In plant cells/ yeast cells:

Pyruvate —> Ethanal which releases CO2
Ethanal is reduced to Ethanol when NADH —> NAD which restarts glycolysis

In animals cells:

Pyruvate is reduced to Lactate when NADH —> NAD which restarts glycolysis

Question 9

Describe the end of glycolysis if respiration is aerobic.

Answer 9

Pyruvate is actively transported into the mitochondrial matrix

Question 10

Describe the link reaction.

Answer 10

1. 2 x Pyruvate is oxidised to form 2 x acetate by the removal of 2 x CO2 and the reduction of NAD to NADH
2. Coenzyme A combines with acetate to produce 2 x Acetyl CoA

Question 11

Describe the Krebs cycle.

Answer 11

1. Acetyl CoA reacts with a 4C molecule to produce a 6C molecule and CoA is released
2. Redox reactions occur as FAD and NAD are reduced
3. CO2 is released
4. ATP is made by substrate level phosphorylation

Krebs cycle occurs twice for every glucose molecule.

Question 12

Why are glucose and pyruvate known as respiratory substrates?

Answer 12

• they are oxidised to release energy in the form of ATP

Question 13

What are the other types of respiratory substrates and, why might they be used in the Krebs cycle?

Answer 13

1. Breakdown products of lipids (fatty acids and glycerol)
2. Amino acids

• glucose might not always be available but ATP needs to be continuously produced to keep the cell alive

Question 14

Describe oxidative phosphorylation.

Answer 14

1. Reduced NAD/FAD release hydrogen at the cristae which is split into protons and electrons
2. Electrons transfer along the ETC in a series of redox reactions which release energy
3. Energy released is used to pump protons from the matrix across the crista membrane into the intermembrane space
4. This forms an electrochemical gradient and protons diffuse through ATP Synthase
5. Many ADP + Pi form many ATP
6. At the end of the ETC oxygen combines with the protons and electrons to form water
7. Oxygen is the final electron acceptor.