GATE Environmental Science and Engineering Practice Quiz

Question 1

In a batch culture growing exponentially, the biomass concentration increases from 0.20 g/L to 1.60 g/L in 6 hours. Assuming no lag phase during this interval, what is the specific growth rate, μ?

Accepted Answer

0.347 h^-1

Question 2

For a microorganism following Monod kinetics, the maximum specific growth rate is 0.80 h^-1 and the half-saturation constant Ks is 20 mg/L. What is μ when the substrate concentration is 20 mg/L?

Accepted Answer

0.40 h^-1

Question 3

For substrate-limited growth following Monod kinetics, which statement is correct when S << Ks?

Accepted Answer

μ ≈ μmax S/Ks and is approximately first-order in S

Question 4

In a chemostat at steady state with influent substrate concentration S0 = 100 mg/L, μmax = 0.80 h^-1, Ks = 20 mg/L, and dilution rate D = 0.40 h^-1, what is the steady-state substrate concentration S in the reactor? Assume no decay.

Accepted Answer

20 mg/L

Question 5

A chemostat is operated at steady state with dilution rate D = 0.30 h^-1 and negligible decay. If washout does not occur, what is the specific growth rate of the microorganism in the reactor?

Accepted Answer

0.30 h^-1

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