Q.12 In balanced growth phase of a cell
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- P. all components of a cell grow at the same rate
- Q. specific growth determined by cell number or cell mass would be the same
- R. the growth rate is independent of substrate concentration
- S. the growth rate decreases with decreasing substrate concentration
- (A) P, Q and S only
- (B) Q, R and S only
- (C) P, Q and R only
- (D) P only
In the balanced growth phase (exponential/log phase), all cell components grow proportionally at a constant rate independent of substrate depletion. This SEO-optimized article answers the MCQ: In balanced growth phase of a cell P. all components grow same rate, Q. specific growth by number/mass same, R. growth rate independent of substrate, S. growth decreases with substrate—selecting (C) P, Q and R only, ideal for microbiology and bioprocess engineering students.
Correct Answer: Option (C) P, Q and R Only
Balanced growth occurs during exponential phase where:
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P. All components grow same rate: True. Proteins, DNA, RNA, organelles double proportionally per generation, maintaining constant cell composition.
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Q. Specific growth (μ) by cell number or mass same: True. μ = ln2/generation time identical whether measured by OD600 (mass) or CFU (number).
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R. Growth rate independent of substrate concentration: True. Above saturation constant (Ks), Monod kinetics yield maximal μ_max unaffected by [S].
S is false—that’s deceleration phase as [S] approaches Ks.
Explanation of All Statements
Statement Phase Characteristic True in Balanced Growth? Reason P Proportional biosynthesis True Constant RNA/protein ratio Q μ_number = μ_mass True Doubling time identical metrics R μ independent of [S] True [S] ≫ Ks saturation kinetics S μ decreases with [S] False Describes deceleration phase Option Analysis:
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(A) P,Q,S: Wrong—S false
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(B) Q,R,S: Wrong—S false
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(C) P,Q,R: Correct—defines balanced growth
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(D) P only: Incomplete
Biotechnology Relevance
Balanced growth enables accurate μ calculation for bioreactor scale-up, F0D0 modeling, and fermentation yield optimization—directly linking to your microbial kinetics expertise. Specific growth rate constancy validates chemostat steady-state analysis.
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