Lactose is more likely to be utilised by E. Coli than Arabinose because Lactose will yield more energy (ATP) and lactose breakdown will give glucose and galactose and these will enter into the glycolytic pathways to pyruvate for ATP generation until Arabinose which will undergo Pentose phosphate pathway and this does not produce enough energy.
The molecule that would be affected by 'limited nitrogen' is the myofibrillar proteins in muscle. Explanation: The myofibrils of the muscle have a number of protein molecules.
