Question

Enumerate the assumptions that we undertake in making the respiratory balance sheet. Are these assumptions valid for a living system? Compare fermentation and aerobic respiration in this context.

Answer 1

Assumption made for the respiratory balance sheet:

The assumptions made for the respiratory balance sheet are:

1. These metabolic pathways should occur in the sequential and orderly manner.
2. NADH produced in glycolysis moves into the mitochondria for oxidative phosphorylation.
3. Intermediates produced in the pathway are not utilized in other biochemical processes.
4. The substrate for respiration is only glucose and other substrates like fats or proteins do not enter the process in any intermediate steps.

Assumptions for living system:

The assumptions made for the respiratory balance sheet are not applicable for the living systems.

• The metabolic pathways such as glycolysis, krebs cycle do not strictly occur in the sequential manner.
• Depending on the concentration of metabolites, availability of oxygen gas, in the cell, a metabolic pathway is chosen.

Comparison between Aerobic respiration and fermentation

Criteria	Aerobic respiration	Fermentation
Definition	Aerobic respiration is the process where complete oxidation of glucose takes place.	Fermentation is the process where partial oxidation of glucose takes place.
Net gain of ATP	38 molecules of ATP	2 molecules of ATP