An activated-sludge waste treatment system is required to reduce the amount of BOD₅ from 1000 mg/l to 20 mg/l at the exit. The sedimentation unit concentrates biomass by a factor of 3. Kinetic parameters are µ_m = 0.2 h-1 , K_s = 80 mg/l, k_d = 0.01 h-1 , and Y ^M _X/S = 0.5 g MLVSS/g BOD₅. The flow of waste water is 10000 l/h and the size of the treatme nt basin is 50,000 l. What value of the recycle ratio must be used?

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#Question id: 13108

#Section 7: Recombinant DNA technology and Other Tools in Biotechnology

With the help of DNA fingerprinting which can be used to determine paternity. There are three babies (Baby A, Baby B and Baby C) in a maternity ward, and three sets of confused and worried parents. (Father and Mother #1 are a couple, as are Father and Mother #2, and Father and Mother #3.) 

You do each PCR reaction on chromosome 15 and load each one into a separate well of an agarose gel, and then run the gel.

 

 Why is it that some people show three bands?

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#Question id: 3558

#Section 3: Genetics, Cellular and Molecular Biology

Cystic fibrosis (CF) is a Mendelian disorder in the human population that is inherited as a recessive. Normal parents have two children with CF. The probability of their next child being normal son for this characteristic.

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#Question id: 13153

#General Aptitude

The in-radius of an equilateral triangle is of length 3 cm. Then the length of each of its medians is

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#Question id: 15649

#Section 4: Fundamentals of Biological Engineering

A bacterial culture having a specific oxygen uptake rate of 5 mmol O2 (g DCW)⁻¹ h⁻¹ is being grown aerobically in a fed-batch reactor. The maximum value of the volumetric oxygen transfer coefficient is 0.18 s⁻¹ for the stirred tank bioreactor and the critical dissolved oxygen concentration is 20% of the saturation concentration (8 mg L⁻¹). The maximum density to which the cells can be grown in the fed-batch process, without the growth being limited by oxygen transfer, is approximately

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#Question id: 14508

#Section 1: Engineering Mathematics

There are three events A, B and C, one of which must occur and only one can happen, the odds are 8 to 3 against A, 5 to 2 against B; find the probability of C.