
Concept explainers
Introduction:
The 1st line of defense in the body is the system, which helps in the prevention of the entrance of the pathogen from outside the body. This system is present in the gut, respiratory system and the skin, and kills the pathogen before it enters to blood stream.

Answer to Problem 1Q
Correct answer:
The correct answer is option (b) skin provides more surface area than mucosal surface for commensal microbes.
Explanation of Solution
Explanation/justification for the correct answer:
Option (b) skin provides a larger surface area than the mucosal commensal microbes. The skin has a very less amount of the commensal microbiota as compared to gut mucosal bacteria. It is an incorrect statement. Hence, it is the correct answer.
Explanation/justification for the incorrect answer:
Option (a) mucosal surfaces are better than the skin surface for commensal microbes. The mucosal surface is better for the microbes, as the mucosal surface is good for adherence, nutrition and is not shed regularly. Hence, it is an incorrect answer.
Option (c) there are 10 times more bacteria residing in the human intestine than the number of the cells in human. It is correct, the number flora of the intestine has a high number of the bacteria. Due to the small size and colonization capability, the bacteria remain intact there and maintain their population. Hence, it is an incorrect answer.
Option (d) it is common for the bacteria to live in commensal relationship with human body. It is correct, many bacteria live inside and the outer side of our body. The bacteria present in the intestine are very good example of symbiosis, as they get nutrition from the food and help in digestion. Hence, it is an incorrect answer.
Option (e) during gestation, the fetus does not have any bacteria. It is correct, during gestation, the bacteria are not present inside the body. They come after the birth, when the baby start eating food, they come own their own and reside inside the body. Hence, it is an incorrect answer.
The skin has a very less amount of the commensal microbiota as compared to gut mucosal bacteria. It is an incorrect statement.
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