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TLS Online TPP Program

#Question id: 9609

Dozens of potato varieties exist, differing from each other in potato-tuber size, skin color, flesh color, and shape. One might construct a classification of potatoes based on these morphological traits. Which of these criticisms of such a classification scheme is most likely to come from an adherent of the phylocode method of classification?

#XL - S Microbiology
  1. Flesh color, rather than skin color, is a valid trait to use for classification because it is less susceptible to change with the age of the tuber.
  2. Flower color is a better classification criterion, because below-ground tubers can be influenced by minerals in the soil as much as by their genes.
  3. The only biologically valid classification of potato varieties is one that accurately reflects their genetic and evolutionary relatedness.
  4. The most accurate phylogenetic code is that of Linnaeus. Classify potatoes based on Linnaean principles; not according to their color.
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TLS Online TPP Program

#Question id: 35937

#XL - U Food Technology

Which of the following are true regarding D-value (Decimal reduction time) in microbial death kinetics?
TLS Online TPP Program

#Question id: 35938

#XL - U Food Technology

Which of the following statements are correct about the Z-value in microbial thermal death kinetics?
A. Z-value is the temperature increase required to reduce the D-value by one log cycle.
B. A higher Z-value indicates that the microorganism is more sensitive to temperature changes.
C. Z-value helps in comparing the thermal resistance of different microorganisms.
D. Z-value is independent of the heating medium.
E. Z-value can be used to optimize time-temperature combinations in thermal processing.
TLS Online TPP Program

#Question id: 35939

#XL - U Food Technology

A bacterial culture has an initial population of 1×104cells/mL. The population doubles every 30 minutes. What will be the population (in cells/mL) after 2 hours?
TLS Online TPP Program

#Question id: 35940

#XL - U Food Technology

In a batch culture, the specific growth rate (𝜇) of a microbe is 0.693 h-1. What is the doubling time (in hours) of this organism?
TLS Online TPP Program

#Question id: 35941

#XL - U Food Technology

A microbial population declines from 1×108CFU/mL to 1×104CFU/mL in 30 minutes during thermal processing. Assuming first-order death kinetics, calculate the decimal reduction time (D-value) in minutes.
(Use: 𝑁=𝑁0×10−𝑡 / 𝐷)
TLS Online TPP Program

#Question id: 35942

#XL - U Food Technology

A microorganism has a D-value of 5 minutes at 121°C. How much time (in minutes) is required to achieve a 6-log reduction at this temperature?
( Time = D × log reduction)