Respiration- past paper qs

Question 1

Why does aerobic respiration yield fewer molecules of ATP than the theoretical
maximum

Answer 1

-some ATP used to (actively) transport pyruvate
(into the mitochondrion) ;
- some ATP used to (actively) transport
H(+) from (reduced) NAD ,
formed in glycolysis / into the mitochondrion

Question 2

Explain why the incomplete breakdown of glucose in anaerobic respiration produces less ATP than aerobic respiration.

Answer 2

glycolysis / conversion of glucose into pyruvate ,occurs ;

produces 2 molecules of ATP (net) ;
(only) substrate level phosphorylation (occurs) ;
oxygen not available as final electron acceptor ;
pyruvate / ethanal ,
used to regenerate NAD for glycolysis (to continue) ;
6 (Krebs cycle and)
electron transport chain / chemiosmosis /
oxidative phosphorylation ,
do not occur ;

Question 3

The anaerobic respiration pathway in animal cells can be reversed, but the anaerobic
respiration pathway in yeast cells cannot be reversed.
Explain why, using your knowledge of the differences between the two pathways.

Answer 3

-in lactate fermentation, lactate can be converted back to pyruvate via enzyme dehydrogenase
-in ethanal fermentation, CO2 released in order for ethanol to be produced, carboxylase enzyme unable to reverse reaction
-or 3C-2C so cannot be reversed

Question 4

Outline the process of glycolysis

Answer 4

phosphorylation of glucose ;
2 so forming hexose (1,6) bisphosphate ;
3 (then) splitting into / formation of ,
two / 2 , triose phosphate(s) / TP ;
4 (for formation of pyruvate) dehydrogenation /
oxidation / formation of reduced NAD ;
5 yruvate produced (from , TP / (3C) intermediate) ;
6 total production 4 ATP / net production of 2 ATP ;

Question 5

Suggest the type of reaction that removes a phosphate group from an ATP molecule.

Answer 5

hydrolysis

Question 6

State the precise location of the electron transport chain in the cell

Answer 6

cristae

Question 7

hydrogen acceptor for mammals vs yeast in anaerobic respiration

Answer 7

-pyruvate in mammals
-ethanal in yeast

Question 8

final product in mammals vs yeast in anaerobic respiration

Answer 8

-lactate in mammals
-ethanol in yeast