The assumptions which are taken for the making of the respiratory balance sheet are:

i) The metabolic pathway for respiration is sequential as:

Glycolysis � Kreb’s Cycle � Electron transport system.

Each of the above occurs one after the other in sequential order.

ii) The NADH which is synthesized during the glycolysis process is taken from the cytoplasm to the mitochondria of the cell, where oxidation occurs along with electron transport.

iii) The intermediate which is formed by the various biochemical respiration pathways is not used as raw material for any other respiration pathway.

iv) Glucose is the sole respiratory substrate, and no other substrate can enter the glycolytic pathway at any particular step of the process.

These assumptions are not always valid for an organism because:

i) All the biochemical pathways do not follow a sequential order, and instead, they occur simultaneously.

ii) The substrates are constantly entering in the intermediate steps of the biochemical respiratory pathway.

iii) The ATP molecules are used whenever it is required and formed by the body.

iv) The enzyme functions rate is controlled by various functions, and it is not controlled by only a single mechanism from a single site.

Difference between fermentation and aerobic respiration: