Home › MCQs › BioTechnology › Question #10603
Back to Questions
BioTechnology QUESTION #10603
Question 1
The distinction between primary and secondary metabolites in antibiotic fermentation is that:
  • Primary metabolites are toxic; secondary metabolites are non-toxic
  • Primary metabolites are produced during active growth (tropophase); antibiotics are secondary metabolites produced after growth slows (idiophase)✔️
  • Secondary metabolites are always produced in larger quantities than primary metabolites
  • Primary metabolites include only nucleic acids; secondary metabolites include all proteins
Correct Answer Explanation
In antibiotic fermentation, primary metabolites (amino acids, nucleotides, lipids) are produced during the growth phase (tropophase) when all nutrients are available. Secondary metabolites (antibiotics, pigments, toxins) are produced during the idiophase, after growth slows due to nutrient limitation. This temporal regulation is critical for industrial optimisation — process engineers manipulate nutrient feeding to extend the idiophase and maximise antibiotic yield.