Communities with a high level of bacterial diversity are found in many habitats including soil and aquatic environments. Recent studies indicate this diversity is crucial to the functioning of these communities. The same studies have also found that phage abundance plays a critical role in the maintenance of the bacterial diversity within these communities. What is the probable role of phages in this community? (Check all that apply.)

Question

A) they act as facilitators

B) they have a mutualistic relationship with the bacteria

C) they parasitize the bacteria

D) they have a commensal relationship with the bacteria

E) they compete with the bacteria for space and nutrients

F) they keep any one species of bacteria from becoming too abundant in the community

Answer 1

C, F

Clarify Question
• What is the key concept addressed by the question?
        o This question requires an understanding of how bacterial diversity is maintained in a community and how bacterial phages may play a role in this diversity.
• What type of thinking is required?
        o This is an analyze question; you need to break down the question into its components in order to determine the role of phages in communities of bacteria. This is a check-all-that-apply question; there may be more than one correct answer.

Gather Content
• What do you already know about maintaining bacterial diversity in a community? What other information is related to the question? 
        o How could an abundance of viruses be beneficial to maintaining a high level of diversity in a bacterial community? When phages infect bacteria, they usually kill the bacteria, which would seem counter to the argument that the phage help maintain bacterial diversity.

Choose Answer
• Given what you now know, what information is most likely to produce the correct answer?
        o Phages are viruses that parasitize bacterial cells. In this situation, the parasites keep any one species of bacteria from becoming dominant, which maintains bacterial diversity in the community.

Reflect on Process
• Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o You need to analyze the question by breaking it down and trying to figure out how having a high level of viruses in an environment help to maintain the bacterial diversity of a community. Did you remember that without predatory pressure on a population, that population can grow unchecked? In that situation, one or two species of bacteria could overtake others and reduce diversity. The phages act as parasites to give many bacterial species a fighting chance and acts to maintain bacterial diversity.