Which of the following is not true regarding the decimal reduction time?
A. Once the number of organisms has been reduced to 10%, the killing may slow due to resistant strains that remain in the population
B. It is the time taken to reduce the number of pathogens in a sample by one log cycle
C. It is a measure of the effective concentration of disinfectant that kills within a specific time period
D. The Z value is the temperature equivalent of the D value
Answer: C
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Pioneering species inhabiting a disturbed area alter the environment and create new habitats
a. False, the habitat cannot be changed by a living organism. b. True, organisms moving to a disturbed area use the resources and can themselves be a resource or can provide resources such as shade. c. False, pioneering species are very short-lived and so do not invest enough time to change the habitat
Heterotrophic bacteria are able to break down large food items
a. by ingesting them with pseudopods. b. with exoenzymes. c. by breaking them up with cilia. d. by crushing with their larger relative size. e. by using their cell membranes to pinch the food into smaller pieces.
What organisms are responsible for harmful algal blooms?
a. Diatoms b. Coccolithophores c. Dinoflagellates d. Ciliates
The greatest concentration of nitrogen on the planet Earth is found in
a. living organisms, including bacteria. b. the atmosphere. c. soil minerals. d. fossil fuels. e. oceans.