Respiration

Question 1

What is the purpose of respiration?

Answer 1

To produce ATP

Question 2

What is the first stage of respiration?

Answer 2

Glycolysis

Question 3

Is glycolysis aerobic or anaerobic?

Answer 3

Anaerobic, does not require respiration

Question 4

Where does glycolysis take place?

Answer 4

In the cytoplasm of the cell

Question 5

What is glucose converted to and how?

Answer 5

hexose 1,6 bisphosphate through phosphorylation by ATP

Question 6

What is hexose 1,6 bisphosphate broken down to?

Answer 6

2 three-carbon molecules- triose phosphate

Question 7

What is the final product of glycolysis and how is it produced?

Answer 7

Pyruvate, made by the dephosphorylation of triose phosphate.

Question 8

What are the net products of glycolysis?

Answer 8

2x ATP, 2x NADH, 2x pyruvate

Question 9

What is the stage that occurs after glycolysis in aerobic conditions?

Answer 9

The link reaction

Question 10

Where does the link reaction occur?

Answer 10

The mitochondrial matrix

Question 11

How does pyruvate get to the link reaction?

Answer 11

It actively transports from the cytoplasm into the matrix of the mitochondria

Question 12

What is pyruvate converted to in the link reaction and how?

Answer 12

Acetate through decarboxylation and oxidation

Question 13

What is the final product of the link reaction and how is it produced?

Answer 13

Acetylcoenzyme A, by binding acetate and coenzyme A

Question 14

What stage occurs after the link reaction?

Answer 14

The Krebs Cycle

Question 15

How many carbons does AcetylcoA contain?

Answer 15

2

Question 16

How is a 6 carbon molecule produced from AcetylCoA in the Krebs Cycle?

Answer 16

Oxaloacetate joins with AcetylCoA to produce citrate

Question 17

How does citrate produce oxaloacetate

Answer 17

• Decarboxylation occurs twice
• 2 NAD molecules are reduced at the same time
• ADP is phosphorylated
• An FAD molecule is reduced
• another NAD molecule is reduced
• Oxaloacetate is produced

Question 18

What are the net products of the Krebs cycle?

Answer 18

3x NADH, 1x FADH₂, 1x ATP, 2x CO₂

Question 19

Where are NADH and FADH₂ transported to after the Krebs Cycle?

Answer 19

The intermembrane space of the mitochondria

Question 20

Where does the electron transport chain take place?

Answer 20

The intermembrane space of the mitochondria

Question 21

What are NADH and FADH₂?

Answer 21

Co-enzymes

Question 22

What happens to NADH and FADH₂ in the electron transport chain?

Answer 22

The are oxidised to release H+ atoms

Question 23

What happens to electrons as they move down the electron transport chain?

Answer 23

They release energy

Question 24

What is the last carrier in the electron transport chain and what is it reduced to?

Answer 24

Oxygen is reduced to water

Question 25

What happens to hydrogen atoms in chemiosmosis?

Answer 25

They are actively transported into the matrix, from which they enter the proton port of the ATP synthase molecules embedded into the membrane

Question 26

What is the name of the proton gradient established at the membrane?

Answer 26

electro-chemical gradient

Question 27

What happens to ATP synthase when H+ diffuses through?

Answer 27

It begins to spin so it gains kinetic energy which allows ADP to be phosphorylated to ATP

Question 28

Describe anaerobic respiration in animals

Answer 28

- glycolysis still occurs - NADH is recycled and oxidised to NAD - Pyruvate acts as a H acceptor so it is converted to Lactate in muscle cells - Lactate is taken to the liver where it is reconverted to pyruvate to continue to the link reaction there

Question 29

Describe anaerobic respiration in yeast

Answer 29

- NAD is recycled - Pyruvate undergoes decarboxylation and reduction to produce ethanol - If the ethanol conc. exceeds 12% all cells will die - Because the ethanol dissolves in cell membranes which causes them to swell and burst

Question 30

What is a respiratory substrate?

Answer 30

An organic substance that can be used for respiration

Question 31

Describe carbohydrates as respiratory substrates

Answer 31

Glucose is the main respiratory substrate | The brain and blood cells can only use glucose

Question 32

Describe proteins as respiratory substrates

Answer 32

Some of the molecule can be changed to glycogen Some is converted to pyruvate and continue to Krebs cycle Slightly higher energy yield than carbohydrates

Question 33

Describe lipids as respiratory substrates?

Answer 33

Glycerol can be converted to glucose Fatty acids (hydrocarbons) can produce ATP through chemiosmosis Can bind with CoA and enter Krebs cycle Highest energy yield

Question 34

Explain why converting pyruvate to lactate allows the continued production of ATP during anaerobic respiration.

Answer 34

- NAD is regenerated | - Which can be reduced again in glycolysis

Question 35

What is the effect of lactate in muscle cells?

Answer 35

Causes cramps due to toxicity

Question 36

What is the main role of oxygen in respiration?

Answer 36

Acts as an electron acceptor as it is reduced to form water (addition of electrons)