Concept explainers
The presence of lipid A in the outer membranes of Gram-negative bacteria ________.
- a. affects the formation of blood clots in the host
- b. causes these bacteria to be oxidase positive
- c. triggers the secretion of a protease enzyme to cleave lgA in mucus
- d. enables enteric bacteria to ferment glucose anaerobically
Introduction:
Many gram-negative bacteria act as a pathogen in various host organisms. The outermost membrane of the cell wall of these bacteria contains “Lipid A”, also known as endotoxin. Lipid A can cause ailments like fever, dilation of blood vessels, inflammation, and formation of blood clots, throughout the blood vessels which is termed as “Disseminated Vascular Coagulation”. Most of the Gram-negative bacteria can affect the immune system of the host and cause various diseases, and sometimes even death.
Answer to Problem 1MC
Correct answer:
Blood clot formation in the blood vessels is affected by the presence of “gram-negative bacteria in humans”. Therefore, option (a) is correct.
Option (a) is given as “affects the formation of blood clots in the host”.
Explanation of Solution
Justify the reasons for the correct statement:
Gram-negative bacteria are usually pathogenic in the host organism. They contain Lipid A in the outermost membrane of their cell walls. Lipid A causes ailments like “fever, blood vessel dilation, inflammation, and the formation of blood clots throughout the blood vessels in the host”.
Hence, option (a) is correct.
Justify the reasons for the incorrect statements:
Option (b) is given as “causes these bacteria to oxidase positively”.
The presence of Lipid A in the cell wall is not a factor for testing positively in the oxidase test for bacteria. It causes diseases like fever and affects the blood clot formation. Hence, it is the wrong answer.
Option (c) is given as “triggers the secretion of a protease enzyme to cleave IgA in mucus”.
The secretion of protease enzyme is not affected by the presence of Lipid A. Hence, it is the wrong answer.
Option (d) is given as “enables enteric bacteria to ferment glucose anaerobically”.
Presence of Lipid A in Gram-negative bacteria is not involved in the anaerobic fermentation of glucose by bacteria. Hence, it’s the wrong answer.
Therefore, options (b), (c), and (d) are incorrect.
Gram-negative bacteria contain Lipid A in the outermost membrane of their cell wall which causes various diseases in the host organism, including the emergence of blood clots everywhere in the blood vessels.
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Chapter 20 Solutions
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