Respiration

Question 1

aerobis respiration stages

Answer 1

1. glycolysis
2. link reaction
3. krebs cycel
4. oxidative phosphorylation

Question 2

Where does glycolysis occur?

Answer 2

Cytoplasm

Question 3

Describe glycolysis (4 marks)

Answer 3

1. Phosphorylation of glucose using ATP;
2. Oxidation of triose phosphate to pyruvate;
3. Net gain of (2) ATP (molecules);
4. NAD reduced/ NADH produced;

Question 4

Dehyrogenase action during glycolysis

Answer 4

Removes hydrogen from triose phosphate so oxidised to pyruvate

Adds hydrogen to NAD so reduced to NADH

Question 5

During glycolysis, ATP is produced via ____________-____________ phosphorylation

Answer 5

substrate-level

Question 6

Net yield of 2 ATP during glycolysis

Answer 6

2 ATP used to phosophorylate glucose

4 ATP produced during substrate level phosphorylation (triose phosphate to pyruvate)

Question 7

Link reaction location

Answer 7

(Mitochondrial) matrix

Question 8

Fill in the blanks:

During the first step of the link reaction pyruvate is oxidised to [1] and the removed hydrogen is used to reduce [2]. During this step, carbon [3] is also released/removed by the enzyme [4].

Answer 8

1. acetate
2. NAD
3. dioxide
4. decarboxylase

Question 9

Carbons in pyruvate

Answer 9

3

Question 10

Carbons in acetate

Answer 10

2

Question 11

Describe how acetylcoenzyme A is formed in the link reaction (2 marks)

Answer 11

1. Oxidation of / hydrogen removed from pyruvate AND carbon dioxide released;
2. Addition of coenzyme A (to 2C acetate).

Question 12

Link reaction reactants

Answer 12

Pyruvate
NAD
CoenzymeA

Question 13

The Krebs cycle is a series of oxidation-reduction reaction that produces………

Answer 13

Products through oxidation-reduction:

Reduced NAD / NADH
Reduced FAD / FADH

Question 14

Importance of the 4C product from the Krebs cycle

Answer 14

Allows the Krebs cycle to continue;

So more NADH and FADH produced;

So more ATP can be produced during oxidative phosphorylation

Question 15

TRUE OR FALSE:

FADH is produced during the link reaction and Krebs cycle

Answer 15

FALSE

FADH is only produced during the Krebs cycle

Question 16

Malonate inhibits a reaction in the Krebs cycle.

Explain why malonate would decrease the uptake of oxygen in a respiring cell (2 marks).

Answer 16

1. Less/no reduced NAD/ reduced FAD
2. Oxygen is the final/terminal (electron) acceptor;

Less NADH/FADH = less electron transfer, so less oxygen required.

Question 17

Oxidative phosphorylation location

Answer 17

In the cristae (the folds of the inner mitochondrial membrane)

Question 18

Describe how ATP is made in mitochondria (6 marks).

Answer 18

1. ATP produced in Krebs cycle by Substrate level phosphorylation
2. Krebs cycle and link reaction produces NADH;
   OR Krebs cycle produces FADH;
3. Electrons released from NADH / FADH;
4. (Electrons) pass along carriers / through electron transport chain / through series of redox reactions;
5. Energy released;
6. Protons move into intermembrane space (electrochemical / proton gradient forms);
7. Protons move down electrochemical gradient and release energy used to combine
8. ADP + Pi;
9. ATP synthase

Question 19

Explain why oxygen is needed for the production of ATP on the cristae of mitochondria (3 marks)

Answer 19

1. ATP formed as electrons pass along transport chain (ETC);
2. Oxygen is final electron acceptor / accepts electrons from electron transport chain;
3. Electrons cannot be passed along electron transport chain if there is no O2 to accept them;

Question 20

Describe how oxidation takes place in glycolysis and in the Krebs cycle (4 marks).

Answer 20

1. Removal of hydrogen;
2. By enzymes/dehydrogenases;
3. H accepted by NAD / reduced NAD formed;

(Triose phosphate is oxidised)

4. In Krebs cycle, FAD (used as well);

Question 21

TRUE OR FALSE:

Fatty acids, glycerol and amino acids can also enter the Krebs cycle to contribute to the generation of ATP

Answer 21

TRUE

Question 22

Which organisms produce carbon dioxide AND ethanol during anaerobic respiration?

Answer 22

Yeast
Bacteria
Some plants

Question 23

Products of anaerobic respiration in animal cells

Answer 23

Lactate / lactic acid

ATP (net yield of 2 ATP)

NAD

Question 24

2 main phases of anaerobic respiration

Answer 24

Glycolysis
Regeneration of NAD

Question 25

Explain why converting pyruvate to lactate allows the continued production of ATP during anaerobic respiration (2 marks).

Answer 25

1. Regenerates NAD
   (accept oxidises reduced NAD);
2. NAD used in glycolysis.

Question 26

Humans synthesise more than their body mass of ATP each day.

Explain why it is necessary for them to synthesise such a large amount of ATP.

Answer 26

ATP cannot be stored / is an immediate source of energy;
ATP only releases a small amounts / packets of energy at a time;

Question 27

Aerobic respiration produces more ATP per molecule of glucose than anaerobic respiration.

Explain why (2 marks).

Answer 27

1. Oxygen is final/terminal (electron) acceptor /
2. (This allows aerobic respiration) oxidative phosphorylation / electron transfer chain;
3. Anaerobic (respiration) only glycolysis occurs
   (so some ATP produced via substrate level phosphorylation)

Question 28

Equipment used to measure the
rate of respiration

Answer 28

respirometer

Question 29

In an experiment using a respirometer, apart from time, give two measurements the student would have to make to determine the rate of aerobic respiration of these seeds in cm^3 hour^–1.

Answer 29

1. Distance liquid moves;
2. Diameter/radius of the tubing/lumen