Respiration

Question 1

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

Answer 1

Oxygen is final/terminal (electron) acceptor / oxygen combines with electrons and protons;
(Aerobic respiration) oxidative phosphorylation / electron transfer chain;
Anaerobic (respiration) only glycolysis occurs / no Krebs / no link reaction;

Question 2

Explain why a log scale is used to record the number of cells.

Answer 2

Large range/difference/increase in numbers;

Question 3

Many yeast cells die during the death phase.

Suggest one reason why

Answer 3

Decrease/no glucose/substrate
OR
Increase in ethanol/carbon dioxide/acidity;

Question 4

Suggest one reason why it was important that the student left the apparatus for one hour after the yeast culture reached a constant temperature.

Answer 4

(So the) oxygen is used/absorbed/respired;

Question 5

During her investigation, the coloured liquid moved to the right.
Explain why it moved to the right.

Answer 5

1. Anaerobic respiration produces carbon dioxide;

2. Increase in pressure/volume (of gas);

Question 6

Suggest and explain why the chosen temperature was 20 °C for this experiment.

Answer 6

(Optimum temperature) for enzymes involved in respiration.

Optimum temperature / temperature for normal growth of seeds;

Question 7

describe how ATP is made in mitochondria

Answer 7

Substrate level phosphorylation / ATP produced in Krebs cycle;

Krebs cycle / link reaction produces reduced coenzyme / reduced NAD / reduced FAD;

Electrons released from reduced / coenzymes / NAD / FAD;

(Electrons) pass along carriers / through electron transport chain / through series of

Energy released;

ADP/ADP+Pi;

Protons move into intermembrane space

ATP synthase;

Question 8

Plants produce ATP in their chloroplast during photosynthesis. They also produce ATP during respiration. Explain why its important for plants to produce ATP during respiration in addition to during photosynthesis

Answer 8

1. In the dark no ATP production in photosynthesis;
2. Some tissues unable to photosynthesise / produce ATP;
3. ATP cannot be moved from cell to cell / stored;
4. Plant uses more ATP than produced in photosynthesis;
5. ATP for active transport / synthesis (of named substance);

Question 9

Another substance in the Krebs cycle is called succinylcholine coenzyme A this substance is a very similar shape to acetyl coenzyme A
Suggest how the production of succinylcholine coA could control the rate of a reaction catalysed by citrate synthase

Answer 9

Is a competitive inhibitor / attaches to active site; prevents E-S complexes from forming

Question 10

Describe how acetyl-CoA is formed in the link reaction

Answer 10

Oxidation of / hydrogen removed from pyruvate and carbon dioxide released;
Addition of coenzyme A.

Question 11

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

Answer 11

Regenerates / produces NAD / oxidises reduced NAD;

(NAD used) in glycolysis.

Question 12

describe the part played by the in a membrane of mitochondria in producing ATP

Answer 12

Electrons transfer down the electron transport chain
Provide energy to take protons into space between membranes
Protons pass back through the membrane into matrix through ATP synthase
Energy used to combined ADP and phosphate to produce ATP

Question 13

Explain why converting pyruvate to ethanol is important in allowed to continue production of ATP and anaerobic respiration

Answer 13

Allows NAD to be recycled so that glycolysis can proceed some more glucose can be converted to pyruvate

Question 14

Give two ways in which anaerobic respiration of glucose is similar to anaerobic respiration of glucose in muscle cells

Answer 14

ATP formed

pyruvate formed

Question 15

Give two ways in which anaerobic respiration of glucose is for anaerobic respiration of glucose in muscle cells

Answer 15

ethanol formed by yeast, lactate by muscle cells

CO2 released by yeast but not muscle cell

Question 16

Describe the roles of the co enzyme and carrier proteins in the synthesis of ATP

Answer 16

NAD / FAD reduced / hydrogen attached to NAD / FAD;

H+ ions / electrons transferred from coenzyme to coenzyme /
carrier to carrier / series of redox reactions;

energy made available as electrons passed on;

energy used to synthesise
ATP from ADP and phosphate / using ATPase;

H+ / protons passed into intermembrane space;

H+ / protons flow back through stalked particles / enzyme;

Question 17

Mitochondria muscle cells in cristea then mitochondria and skin cells explain the advantage of mitochondria muscle cells having more Cristae

Answer 17

(more cristae / larger surface area) for electron transport chain /
more enzymes for ATP production / oxidative phosphorylation; muscle cells use more ATP (than skin cells)(not just more respiration);

Question 18

Pyruvate is formed in the breakdown of glucose during respiration when there is sufficient oxygen this pyruvate is fully broken down in the two substances formed from the pyruvate

Answer 18

CO2
water
ATP

Question 19

Some of the lactate is oxidised provoked by muscles when they are well supplied with oxygen. Suggest an advantage of the lactate being oxidised in the muscles

Answer 19

lactate / pyruvate is an energy source;
muscles have increased / immediate energy or ATP supply; (accept lactate replenishes glycogen or glucose)
restores pH levels;

Question 20

If there was a shortage of oxygen in muscle cells drinks and some pyruvate is converted to lactate but my muscles become fatigued when insufficient oxygen is available

Answer 20

build up / increased concentration of lactate lowers
increased H+/ acidity
enzymes / named protein inhibited(not denatured);