Respiration

Question 1

What is the first step in glycolysis involving glucose?

Answer 1

Phosphorylation of glucose using ATP.

Question 2

What happens to triose phosphate during glycolysis?

Answer 2

Oxidation of triose phosphate to pyruvate.

Question 3

What is the net ATP gain from glycolysis?

Answer 3

Net gain of ATP.

Question 4

What happens to NAD during glycolysis?

Answer 4

NAD is reduced.

Question 5

Where does glycolysis occur in the cell?

Answer 5

In the cytoplasm.

Question 6

Where does the link reaction take place?

Answer 6

In the matrix of the mitochondrion.

Question 7

What happens to pyruvate in the link reaction?

Answer 7

Pyruvate is oxidised and decarboxylated into acetate.

Question 8

What are the products of pyruvate oxidation?

Answer 8

Reduced NAD and CO2.

Question 9

What does acetate combine with?

Answer 9

Coenzyme A to form Acetyl CoA.

Question 10

Is ATP produced during the link reaction?

Answer 10

No ATP is formed.

Question 11

How does oxidation take place in glycolysis and Krebs cycle?

Answer 11

Removal of hydrogen (dehydrogenation).

Question 12

What enzymes are involved in oxidation?

Answer 12

Enzymes called dehydrogenases.

Question 13

What accepts hydrogen atoms removed?

Answer 13

NAD, which gets reduced to NADH.

Question 14

What other molecule accepts hydrogens in the Krebs cycle?

Answer 14

FAD is also used.

Question 15

How is water formed at the end of aerobic respiration?

Answer 15

Oxygen is the final electron acceptor.

Question 16

What combines to form water?

Answer 16

Oxygen combines with electrons and protons.

Question 17

How is ATP production increased inside mitochondria?

Answer 17

Oxidation/removal of electrons and H+ from pyruvate and acetyl CoA (6 carbon compound).

Question 18

Where does substrate-level phosphorylation occur?

Answer 18

In the Krebs cycle.

Question 19

Which coenzymes are produced for electron transport?

Answer 19

Reduced NAD and FAD.

Question 20

Where in mitochondria does the electron transport chain operate?

Answer 20

In the matrix and inner membrane.

Question 21

How do electrons move in the electron transport chain?

Answer 21

Electrons pass along carriers through a series of redox reactions.

Question 22

What does energy released from electrons do?

Answer 22

Pumps protons into the intermembrane space.

Question 23

How is ATP finally produced?

Answer 23

Protons move through ATP synthase to join ADP and Pi, forming ATP.

Question 24

What happens to NAD and FAD during oxidative phosphorylation?

Answer 24

They become reduced by attaching hydrogen.

Question 25

How are H+ ions and electrons transferred?

Answer 25

From coenzyme to coenzyme, carrier to carrier in the electron transport chain on cristae.

Question 26

What is the purpose of energy released during electron transfer?

Answer 26

To pump protons into the intermembrane space, creating an electrochemical gradient.

Question 27

How is ATP synthesized?

Answer 27

Protons flow back through ATP synthase producing ATP from ADP and phosphate.

Question 28

How do uncoupling proteins help maintain body temperature during hibernation?

Answer 28

Allow passage of protons/H+ across membrane.

Question 29

What happens to the energy released?

Answer 29

It is released as heat instead of making ATP.

Question 30

Why do mitochondria in muscles have many cristae?

Answer 30

To provide a larger surface area for the electron transport chain.

Question 31

What advantage does this give muscles?

Answer 31

More ATP is produced, supplying more energy for contraction.

Question 32

Why is the respirometer left for 10 minutes in the water bath?

Answer 32

To reach equilibrium.

Question 33

What else happens during the 10-minute wait?

Answer 33

Allow expansion of gases/liquids and stabilization of seed respiration rate.

Question 34

Why does the coloured liquid move to the left in a respirometer?

Answer 34

Oxygen is taken up by the organism.

Question 35

What happens to carbon dioxide produced?

Answer 35

It is absorbed by potassium hydroxide (KOH).

Question 36

What is the effect on pressure/volume inside the apparatus?

Answer 36

Pressure and volume decrease, moving the liquid.

Question 37

Apart from time, what measurements must be made to calculate respiration rate (cm³/hr)?

Answer 37

Distance liquid moves and diameter or radius of the tube.

Question 38

Why is a log scale used to record numbers of cells/bacteria?

Answer 38

Because there is a large range or difference in numbers.

Question 39

What kind of increase justifies log scale use?

Answer 39

Exponential increase.

Question 40

Why does converting pyruvate to lactate allow continued ATP production anaerobically?

Answer 40

It regenerates NAD by oxidising reduced NAD.

Question 41

How does this affect glycolysis?

Answer 41

Glycolysis continues.

Question 42

How does malonate decrease oxygen uptake in respiration?

Answer 42

It inhibits reactions in the Krebs cycle.

Question 43

What happens to reduced NAD/coenzymes?

Answer 43

Less or none are produced, so fewer hydrogens/electrons are passed to the electron transport chain.

Question 44

Why does this reduce oxygen uptake?

Answer 44

Because oxygen is the final electron acceptor and fewer electrons reach it.