respiration incorrect Qs

Question 1

Why does the incomplete breakdown of glucose in anaerobic respiration produce less ATP than aerobic respiration?

Answer 1

• Glycolysis: glucose –> pyruvate. Produces net 2 ATP
• Only substrate-level phosphorylation occurs.
• Oxygen not available as FEA therefore no Krebs or ETC/ox. phos.
• Pyruvate/ethanal used to regenerate NAD for glycolysis

Question 2

Why does aerobic resp. produce fewer molecules of ATP than the theoretical maximum?

Answer 2

1 some ATP used to (actively) transport pyruvate (into the mitochondrion)

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

3 some energy released in ETC, is not used to transport H+ (across inner membrane) / is released as heat ;

4 not all the H+ movement (back across membrane) is used to generate ATP / is through ATP synth(et)ase . Leaky.

5 not all the, reduced NAD / red NAD / NADH , is used to feed into the ETC ;

Question 3

Why can the anaerobic pathway in animals be reversed but not in yeast?

Answer 3

in animals:
A1 pyruvate is , converted / reduced , to ,
lactate / lactic acid ;
A2 can be reversed as no atoms lost / other product formed ;
A3 lactate dehydrogenase available
to reverse the reaction

in yeast:
Y1 pyruvate converted to ethanol (in 2 steps) and
carbon dioxide / CO2 ;
Y2 cannot be reversed as carbon dioxide is / atoms are , lost
Y3 (de)carboxylase enzyme cannot reverse the reaction ;