Question 1

The normal microbiota provides protection against potentially harmful organisms and stimulates the immune system. Why would the immune responses to members of the normal microbiota cross-react with pathogens?

Accepted Answer

Pathogens can often be closely related to members of the normal microbiota, sharing similar antigens that can trigger cross-reactive immune responses.

Question 2

A number of viruses often include a similar set of symptoms when they cause an infectious disease state (fever, headache, fatigue, runny nose). Why would they all cause the same symptoms if they're different viruses?

Accepted Answer

The symptoms are associated with the immune system's response, not the molecules from the pathogens themselves. Our responses against viruses are fairly similar, regardless of virus type, so the symptoms are similar.

Question 3

Which of the following is NOT a likely reason why diseases caused by opportunists are becoming more frequent in the US population?

Accepted Answer

Option D talks about the potential introduction of new pathogens from travel, which is not directly related to the increasing frequency of diseases caused by opportunists in the US population. Options A, B, and C all discuss factors that lead to weakened immune systems in individuals, making them more susceptible to opportunistic infections.

Question 4

Home-canned foods should be boiled before consumption to prevent botulism. Considering that this treatment does NOT destroy endospores, why would it be helpful in preventing the disease?

Accepted Answer

Boiling the home-canned food would denature the botulism exotoxin and inactivate it. The exotoxin is the main cause of botulism disease symptoms, so this would make the food safer.

Question 5

Why is it a good strategy for a microbe to adhere to a receptor that plays a critical function for a host cell?

Accepted Answer

If a receptor is critical for host cell function and there is no backup system in place, the host cell has no choice but to express it, making it a good target for the microbe to adhere to. However, this also makes the host cell more susceptible to infection.

Question 6

In two of Koch's postulates (#2 and #3), a pure culture of the organism is required. Which of the following would NOT be a possible consequence of using a contaminated culture?

Accepted Answer

Choice D is the only option that correctly states that using a contaminated culture would not have any consequences on the ability to attribute the illness to the microbe in question or infect test animals with the microbe of interest. The presence of a contaminating microbe would not affect the ability to recover the suspect microbe or cause the disease in the test animals as long as the suspect microbe is also present. Therefore, there would be no consequence to using a contaminated culture in this case. Choices A, B, and C all describe potential consequences of using a contaminated culture.

Quiz 16: Host-Microbe Interactions

The normal microbiota provides protection against potentially harmful organisms and stimulates the immune system. Why would the immune responses to members of the normal microbiota cross-react with pathogens?

A number of viruses often include a similar set of symptoms when they cause an infectious disease state (fever, headache, fatigue, runny nose) . Why would they all cause the same symptoms if they're different viruses?

Which of the following is NOT a likely reason why diseases caused by opportunists are becoming more frequent in the US population?

Home-canned foods should be boiled before consumption to prevent botulism. Considering that this treatment does NOT destroy endospores, why would it be helpful in preventing the disease?

Why is it a good strategy for a microbe to adhere to a receptor that plays a critical function for a host cell?

In two of Koch's postulates (#2 and #3) , a pure culture of the organism is required. Which of the following would NOT be a possible consequence of using a contaminated culture?