BIO 203 Lab Quiz # 8 1. When reporting the thermal death time it is necessary to

Question

BIO 203 Lab Quiz # 8 1. When reporting the thermal death time it is necessary to report the temperature at which it was determined. a. True b. False 2. The thermal death time of an endospore is less than that of a vegetative cell. a. True b. False Which of the following types of organisms would you expect to have the longest thermal death time? 3. a. Mesophile b. Psycrotroph c. Thermophile d. Psycrophile 4. Bacillus stearothermophilus is often used as a test organism to determine an effective thermal death time to rid a culture of all organisms. This bacteria is used because a. It is a common contaminant b. It makes endospores c. It is a pyscrophile d. It is a thermophile e. A and C f. B and D 5. A disinfectant is used a. On mucus membranes b. On skin c. On inanimate objects 6. An antiseptic is used a. On inanimate objects b. On living tissue c. To sterilize instruments 7. The effectiveness of a disinfectant is influenced by a. Concentration of the disinfectant b· type of microbe present c. concentration of microbes d. all of the above

Explanation / Answer

1. False, Because the temperature inside the oven, autoclave or waterbath is much higher than the surrounding.

2. False, Thermal death point is much higher for endospore than vegetative cells because they are temprature resistant due to Dipicolinic acid in the core.

3. These are called thermophile and may survive for long time at very high temperature.Option C is correct.

4. The Bacillus stearothermophilus is found in soil and is a thermophile and form highly temperature resistant endospores. It is also used as indicator in sterilization practices. Option F is correct.

5. Disinfectant is used for killing of microbes and spores on inanimate objects. Because it may harmful on tissue and can damage animate structures. Option C is correct.

6. Antiseptic are used to decrease the level of microbial count to non harmful standard on animate objects. These are non harmful to livings. Option b is correct.

7. Effectivity is based on whether the microbes are resistant to chemical or not. And also the conc. Used and no. Of microbes on which disindisinfe is used. Option D is correct.

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