TLS Online TPP Program

#Question id: 8922


Which statement is most consistent with the hypothesis that the Cambrian explosion was caused by the rise of predator-prey relationships?

#XL - R Botany
  1. increased incidence of worm burrows in the fossil record
  2. increased incidence of hard parts in the fossil record
  3. increased incidence of organic material in the fossil record
  4. increased incidence of fern galls in the fossil record
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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)