Question 5(c)
[Maximum number: 4]
Dopamine, serotonin and acetylcholine are neurotransmitters in the human nervous system.
The genetically engineered E. coli was grown in a liquid culture. The concentrations of tryptophan and serotonin in the culture were measured. The graph shows the results. Concentration / a.u.

Discuss the changes shown in the graph. Use the information in the question to support your answer.
