In a mixed bacterial culture of total size N = 1 × 10⁸ cells, a donor strain D carrying a plasmid for antibiotic resistance constitutes 0.1 % of the population. The remaining cells are recipients R that lack the plasmid. Conjugation occurs with a mass‑action rate constant β = 2 × 10⁻⁹ h⁻¹ per donor‑recipient pair. No plasmid loss occurs.

Calculate the expected number of transconjugant cells after 24 h. Also give the proportion of the total population that is resistant after this period. Present the number of transconjugants as an integer and the proportion as a decimal to four places.

Question

In a mixed bacterial culture of total size N = 1 × 10⁸ cells, a donor strain D carrying a plasmid for antibiotic resistance constitutes 0.1 % of the population. The remaining cells are recipients R that lack the plasmid. Conjugation occurs with a mass‑action rate constant β = 2 × 10⁻⁹ h⁻¹ per donor‑recipient pair. No plasmid loss occurs.

Calculate the expected number of transconjugant cells after 24 h. Also give the proportion of the total population that is resistant after this period. Present the number of transconjugants as an integer and the proportion as a decimal to four places.

Accepted Answer

479520 transconjugants; proportion = 0.0048

Waec Model Questions Vol1 2025 Biology Question 10

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