Microbial control methods that kill/destroy _________ are able to sterilize.
- a. viruses
- b. the tubercle bacillus
- c. endospores
- d. cysts
Introduction:
There are various controlling methods like sterilization, disinfection, antisepsis, and decontamination. Sterilization is the microbial growth controlling technique in which all the viable microbes including endospores are destroyed.
Answer to Problem 1MCQ
Correct answer:
Microbial control methods that kill/destroy endospores are able to sterilize. Therefore, option (c) is correct.
Option (c) is given as “endospores”.
Explanation of Solution
Justify reason for the correct statement:
Bacterial endospores are considered the most resistant microbial forms due to their hard impenetrable covering. Endospores are resistant and dormant cells that can remain viable for many years. They are composed of thick walls of peptidoglycan, cytoplasm, and DNA. Endospores contain large quantities of calcium, dipicolinic acid, and DNA binding protein. They are 18 times harder to kill compared to their vegetative cells. Their destruction is the main goal of sterilization as their destruction would indicate the successful destruction of all less resistant forms of microbes.
Hence, option (c) is correct.
Justify reasons for the incorrect statements:
Option (a) is given as “viruses”.
Viruses can be destroyed by various other kinds of physical and chemical control methods. Hence, it is a wrong answer.
Option (b) is given as “the tubercle bacillus”.
It is a bacterium responsible for causing tuberculosis. The vegetative form of bacteria is the least resistant microbial forms. Bacterial structures are destroyed easily by heat or chemical action. High temperatures oxidize the vegetative microbial cells and destroy them. Hence, it is a wrong answer.
Option (d) is given as “cysts”.
Cysts are the resistant structures of the protozoans. Protozoan does not show resistance against most of the control agents and can be easily destroyed. Hence, it is a wrong answer.
Hence, options (a), (b), and (d) are incorrect.
Endospores are the most resistant forms against antimicrobial agents and thus complete sterilization also include their destruction.
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Chapter 11 Solutions
Microbiology: A Systems Approach
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