Nutrient medium is to be heated from 10⁰C to 28⁰C is a single-pass countercurrent shell-and-tube heat exchanger before being pumped into a fed-batch fermenter. Medium passes through the tubes of the exchanger; the shell-side fluid is water which enters with flow rate 3 x 10^4 kg h^- 1 and temperature 60⁰C pre-heated medium is required at a rate of 50 m^3 h^-1. The density, viscosity and heat capacity of the medium are the same as water; the thermal conductivity of the medium is 0.54 Wm^- 1 ⁰C^ - 1. It is proposed to use 30 steel tubes with inner diameter 5 cm; the tubes will be arranged in line. The pipe wall is 5-mm thick; the thermal conductivity of the metal is 50 Wm^- 1 ⁰C^ - 1. The maximum linear shell-side fluid velocity is estimated as 0.15 m s^-1. What is the rate of heat transfer?

#Question id: 3276

#Section 3: Genetics, Cellular and Molecular Biology

Which of these conditions are always true of populations evolving due to natural selection?

Condition 1: The population must vary in traits that are heritable.

Condition 2: Some heritable traits must increase reproductive success.

Condition 3: Individuals pass on most traits that they acquire during their lifetime.

#Question id: 3277

#Section 3: Genetics, Cellular and Molecular Biology

Which of the following describes the most likely order of events in allopatric speciation?

#Question id: 3278

#Section 3: Genetics, Cellular and Molecular Biology

What does the biological species concept use as the primary criterion for determining species boundaries?

#Question id: 3279

#Section 3: Genetics, Cellular and Molecular Biology

Which two of the following have operated to increase divergence between mosquito fish populations on island?

a. improved gene flow

b. bottleneck effect

c. sexual selection

d. founder effect

e. natural selection

#Question id: 3280

#Section 3: Genetics, Cellular and Molecular Biology

Small populations are threatened by the loss of genetic diversity from

a. Inbreeding

b. Genetic drift

c. Limited mating

#Question id: 3282

#Section 3: Genetics, Cellular and Molecular Biology

Natural selection results in different forms of plants which can survive in contaminated or uncontaminated soil. Type of natural selection is