Final answer:
A leucine auxotroph requires the addition of leucine to a minimal medium to grow, as it cannot synthesize this amino acid due to a genetic mutation.
Step-by-step explanation:
A leucine auxotroph is a nutritional mutant that requires leucine for growth because it has a loss-of-function mutation in a gene responsible for the biosynthesis of leucine.
In the context of the scenario provided, a leucine auxotroph would require the addition of leucine to a minimal medium to support its growth.
This is because the auxotroph is unable to synthesize leucine on its own due to a genetic mutation affecting the pathway that normally produces this amino acid.