Respiration

Question 1

four stages of aerobic respiration

Answer 1

• glycolysis
• link reaction
• krebs’ cycle
• oxidative phosphorylation

Question 1

what intermediates and product is formed in glycolysis?

Answer 1

glucose
–> hexose bisphosphate
–> G3P/TP
—> pyruvate

Question 2

what is used/made in glycolysis and where?

Answer 2

2ATP –> 2ADP + 2Pi
(conversion of glucose to hexose bisphosphate)

2NAD –> 2 red NAD
(one per molecule of TP converted to pyruvate)

4ADP + 4Pi –> 4ATP
(conversion of hexose bisphosphate to pyruvate)

Question 3

what is the product of the link reaction?

Answer 3

acetyl coenzymeA

Question 4

what is used/made in the link reaction per molecule of pyruvate?

Answer 4

CO2
(decarboxylation of pyruvate)

NAD –> red NAD

coenzyme A + 2C molecule –> acetyl coA

Question 5

three stages of the link reaction

Answer 5

• decarboxylation
• dehydrogenation
• combination

Question 6

where does glycolysis take place?

Answer 6

cytoplasm of the cell

Question 7

where does the link reaction take place?

Answer 7

mitochondrial matrix

Question 8

intermediates in the krebs’ cycle (and how many carbons are each of them)

Answer 8

• acetyl coA (2) + oxaloacetate (4)
  –> citrate (6)
  –> ketoglutarate (5)

Question 9

what is used/made in the Krebs’ cycle (and where)?

Answer 9

CO2
NAD –> red NAD
(conversion of citrate to ketoglutarate)

CO2
ADP + Pi –> ATP
FAD –> red FAD
2NAD –> 2 red NAD
(conversion of ketoglutarate to oxaloacetate)

Question 10

dehydrogenation

Answer 10

removal of H (usually to reduce NAD or FAD)

Question 11

coenzymes involved in respiration

Answer 11

• NAD (H carrier)
• FAD (H carrier)
• coenzyme A

Question 12

how much ATP does red NAD and red FAD produce in oxidative phosphorylation?

Answer 12

red NAD -> 2.5ATP
red FAD -> 1.5ATP

Question 13

stages of glycolysis

Answer 13

• phosphorylation
• lysis
• dehydrogenation

Question 14

stages in the Krebs’ cycle

Answer 14

• decarboxylation
• dehydrogenation
• decarboxylation
• dehydrogenation

Question 15

respiratory substrate

Answer 15

an organic substance that releases energy in respiration

Question 16

three types of respiratory substrates and rank them in order of energy values

Answer 16

• carbohydrates
• proteins
• lipids

Question 17

why do lipids produce more ATP than carbohydrates?

Answer 17

lipids have a greater proportion of C-H bonds which provides more H+ for chemiosmosis

Question 18

RQ formula

Answer 18

RQ = CO2 produced/O2 consumed

Question 19

why do carbohydrates produce the most ATP?

Answer 19

they enter the cycle of aerobic respiration at the start at glycolysis whereas other substrates may join in other stages like the link reaction or Krebs’ cycle

Question 20

how much energy is released when one molecule of ATP is hydrolysed?

Answer 20

30.6KJmol-¹

Question 21

why can aerobic respiration not take place without oxygen?

Answer 21

• oxygen acts as the final e- (H) acceptor at the end of the e- transport chain
• NAD will not be oxidised back to red NAD

Question 22

which organisms undergo alcoholic fermentation?

Answer 22

• yeast
• fungi
• bacteria

Question 23

alcoholic fermentation sequence

Answer 23

• pyruvate is decarboxylated to form a 2C molecule
• 2C molecule is reduced by accepting the H from red NAD (to form NAD)
• this recycles NAD which can be reduced again in glycolysis

Question 24

overall equation of alcoholic fermentation

Answer 24

C6H12O6 --> 2C2H5OH + 2CO2

Question 25

what organism does lactate fermentation occur in?

Answer 25

animals

Question 26

why is anaerobic respiration important?

Answer 26

- survival technique for babies during and immediately after birth - aquatic animals have fluctuating O2 concentrations in water - O2 used up faster that it can be supplied in repairing muscles (anaerobic respiration supplies muscles with ATP for extra time)

Question 27

sequence of lactate fermentation

Answer 27

- pyruvate is reduced by accepting a H from red NAD to produce NAD - NAD can be reused in glycolysis

Question 28

what happens to lactate to prevent initial cramp and muscle fatigue?

Answer 28

- lactate removed from blood - transported to liver - converted to glycogen OR reoxidised to pyruvate which enters the link reaction/Krebs' cycle once O2 supply is back

Question 29

what happens once O2 is resupplied after anaerobic respiration?

Answer 29

- oxygen debt is repaid - pyruvate from lactate fermentation enters the link reaction/Krebs' cycle

Question 30

how many molecules of ATP is produced from anaerobic respiration?

Answer 30

2 ATP (from glycolysis)

Question 31

substrate level phosphorylation

Answer 31

synthesis of ATP by transfer of a phosphate group from another molecule